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mk1978
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Joined: November 25, 2022
Posts: 71
Location: Olympia, Wa
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 Posted: Fri Mar 17, 2023 2:40 pm Post subject: Starting issues/switch troubleshooting |
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Howdy folks,
Just getting around to firing up my '77 which has a '72 engine, 1st time I tried to start it cranked over for a bit then nothing....after that no click/thunk, nothing except for one other time it engaged starter.
Cleaned up all the grounds & battery connections.
With key "on" I have juice to the coil.
Also ran a jumper from the main wire under the rear seat to battery positive and the starter turns right over, no problems. So I know the starter is fine.
I haven't turned up any good troubleshooting sequences for the later Bugs as far as determining if it's just the switch. I read one post that mentions checking for power at the wires to the headlight switch but that sucker is buried under a bunch of stuff in the front, looks like a hassle to access.
Any thoughts?
thanks,
Mk
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1977 Beetle ('72 engine) |
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cjsuner
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Joined: January 04, 2013
Posts: 476
Location: Bay area CA
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| Posted: Fri Mar 17, 2023 3:02 pm Post subject: Re: Starting issues/switch troubleshooting |
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Sorry may have mis-understood your wire jumper part, but have you checked underneath the car, to check to make sure the solinoid wire is connected? I ask because after failing to turn over my engine a few times recently, my solinoid wire actually fell off it's post!
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71' Super Convertible (Orange)
74 Super Beetle (Red) |
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ashman40
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Joined: February 16, 2007
Posts: 15987
Location: North Florida, USA
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| Posted: Fri Mar 17, 2023 3:41 pm Post subject: Re: Starting issues/switch troubleshooting |
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| mk1978 wrote: |
| Also ran a jumper from the main wire under the rear seat to battery positive and the starter turns right over, no problems. So I know the starter is fine. |
I take this to mean you connected the #50 starter solenoid wire directly to the positive (+) battery terminal and the starter cranked the engine just fine. This confirms your starter is working as long as you get enough current to the starter solenoid #50 terminal.
| mk1978 wrote: |
| I haven't turned up any good troubleshooting sequences for the later Bugs as far as determining if it's just the switch. |
Do you have a digital multimeter? If you don't have one you should buy or borrow one. It is indispensable when it comes to VW electrical problems.
Start by measuring the DC voltage at the battery terminals. A fully charged batter should read 12.6v.
Move to the fuse box. 2 or 3 of the fuses will have voltage while the ignition is OFF. What is your voltage reading here. With new wires the voltage reading here will probably be 12.5v due to the resistance in the length of wire from the battery to the fuse box. Any less than this and your have high resistance in the wires/connections. If it is below 12.0v you should take some time to clean up the wire connections to reduce the voltage loss.
Move to the underside of the ignition switch. Look for the plug at the bottom end of the ignition switch assembly. ID the solid red #30 wire running into the plug. This red wire comes from one of those fuses you just measured at the fuse box. Insert your MM probe into the space around the wire so you can measure the voltage on the wire. The voltage reading here should be almost identical to the fuse box reading as the wire run is short. If the voltage has dropped further it means more resistance from old wires/connectors.
Turn the key to the ON/RUN position and test for voltage on the solid black #15 wire at the ignition switch plug. This is the ignition switched 12v circuit that powers many devices. With these devices now powered, the voltage reading should drop a little. This is your new baseline for voltage while the ignition switch is ON.
With the starter solenoid wire under the rear seat disconnected, test for voltage on the #50 red/black wire coming off the ignition switch plug. There should be 0 volts while the key is in the ON/RUN position. When you turn the key to START the ignition switch will power the red/black #50 wire. The voltage reading should be the same as the reading on the black #15 wire. Any difference in voltage is due to internal resistance in the ignition switch.
Move to the rear seat. With the key in the START position, take a voltage measurement at the end of the disconnected #50 wire below the left rear seat. This reading should be only slightly lower than the voltage reading taken at the other end of this #50 wire at the ignition switch plug. If the voltage is more than 0.1v lower it is due to resistance in the wiring/connectors.
Report back all your voltage readings at the different points in the circuit.
From the ignition switch and the end of the #50 wire run the test multiple times to confirm if the voltage is intermittent or varies in the voltage reading. Both indicate a bad connection in the ignition switch or in the wire/connections. If the voltage that makes it to the end of the #50 wire below the rear seat is less than 12.0v or intermittent, the starter will not reliably crank the engine. If the same inconsistent/intermittent pattern is seen at both ends of the #50 wire the problem is internal to the ignition switch.
This is a common problem with decades old switches. If you have an OE VW ignition switch, I would recommend you carefully take the switch apart and rebuilt it by cleaning the contact surfaces. Unfortunately, after the 1970 model the ignition switches were made mostly of plastic. After a couple decades the plastic becomes brittle and will likely break when you attempt to open up the switch.
You could replace the switch with an aftermarket switch but these are notorious for having much smaller contact areas than the OE VW switches. This means they will burn contacts and fail much sooner. You can add relays to the #50, #15 and #X circuits coming off the aftermarket switch to extend the life of these weak internal contacts indefinitely. Such a relay on the #50 circuit is known as a Hard Start Relay (HSR). If you find the voltage at the #50 circuit under the rear seat is consistently low but above 6.0v you can use a Bosch-style HSR under the rear seat to power the starter solenoid directly from the battery.
_________________
AshMan40
---------------------------
'67 Beetle #1 {project car that never made it to the road  }
'75 Beetle 1200LS (RHD Japan model) {junked due to frame rot}
'67 Beetle #2 {2019 project car - Wish me luck!} |
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mk1978
Samba Member
Joined: November 25, 2022
Posts: 71
Location: Olympia, Wa
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| Posted: Fri Mar 17, 2023 3:58 pm Post subject: Re: Starting issues/switch troubleshooting |
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| ashman40 wrote: |
| mk1978 wrote: |
| Also ran a jumper from the main wire under the rear seat to battery positive and the starter turns right over, no problems. So I know the starter is fine. |
I take this to mean you connected the #50 starter solenoid wire directly to the positive (+) battery terminal and the starter cranked the engine just fine. This confirms your starter is working as long as you get enough current to the starter solenoid #50 terminal.
| mk1978 wrote: |
| I haven't turned up any good troubleshooting sequences for the later Bugs as far as determining if it's just the switch. |
Do you have a digital multimeter? If you don't have one you should buy or borrow one. It is indispensable when it comes to VW electrical problems.
Start by measuring the DC voltage at the battery terminals. A fully charged batter should read 12.6v.
Move to the fuse box. 2 or 3 of the fuses will have voltage while the ignition is OFF. What is your voltage reading here. With new wires the voltage reading here will probably be 12.5v due to the resistance in the length of wire from the battery to the fuse box. Any less than this and your have high resistance in the wires/connections. If it is below 12.0v you should take some time to clean up the wire connections to reduce the voltage loss.
Move to the underside of the ignition switch. Look for the plug at the bottom end of the ignition switch assembly. ID the solid red #30 wire running into the plug. This red wire comes from one of those fuses you just measured at the fuse box. Insert your MM probe into the space around the wire so you can measure the voltage on the wire. The voltage reading here should be almost identical to the fuse box reading as the wire run is short. If the voltage has dropped further it means more resistance from old wires/connectors.
Turn the key to the ON/RUN position and test for voltage on the solid black #15 wire at the ignition switch plug. This is the ignition switched 12v circuit that powers many devices. With these devices now powered, the voltage reading should drop a little. This is your new baseline for voltage while the ignition switch is ON.
With the starter solenoid wire under the rear seat disconnected, test for voltage on the #50 red/black wire coming off the ignition switch plug. There should be 0 volts while the key is in the ON/RUN position. When you turn the key to START the ignition switch will power the red/black #50 wire. The voltage reading should be the same as the reading on the black #15 wire. Any difference in voltage is due to internal resistance in the ignition switch.
Move to the rear seat. With the key in the START position, take a voltage measurement at the end of the disconnected #50 wire below the left rear seat. This reading should be only slightly lower than the voltage reading taken at the other end of this #50 wire at the ignition switch plug. If the voltage is more than 0.1v lower it is due to resistance in the wiring/connectors.
Report back all your voltage readings at the different points in the circuit.
From the ignition switch and the end of the #50 wire run the test multiple times to confirm if the voltage is intermittent or varies in the voltage reading. Both indicate a bad connection in the ignition switch or in the wire/connections. If the voltage that makes it to the end of the #50 wire below the rear seat is less than 12.0v or intermittent, the starter will not reliably crank the engine. If the same inconsistent/intermittent pattern is seen at both ends of the #50 wire the problem is internal to the ignition switch.
This is a common problem with decades old switches. If you have an OE VW ignition switch, I would recommend you carefully take the switch apart and rebuilt it by cleaning the contact surfaces. Unfortunately, after the 1970 model the ignition switches were made mostly of plastic. After a couple decades the plastic becomes brittle and will likely break when you attempt to open up the switch.
You could replace the switch with an aftermarket switch but these are notorious for having much smaller contact areas than the OE VW switches. This means they will burn contacts and fail much sooner. You can add relays to the #50, #15 and #X circuits coming off the aftermarket switch to extend the life of these weak internal contacts indefinitely. Such a relay on the #50 circuit is known as a Hard Start Relay (HSR). If you find the voltage at the #50 circuit under the rear seat is consistently low but above 6.0v you can use a Bosch-style HSR under the rear seat to power the starter solenoid directly from the battery. |
Yes correct, that's how I tested my starter, works great.
I do have a multimeter, this weekend I'll go out and do the tests you have outlined, thanks!
Mk
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1977 Beetle ('72 engine) |
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mk1978
Samba Member
Joined: November 25, 2022
Posts: 71
Location: Olympia, Wa
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| Posted: Sat Mar 18, 2023 4:52 pm Post subject: Re: Starting issues/switch troubleshooting |
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| ashman40 wrote: |
| mk1978 wrote: |
| Also ran a jumper from the main wire under the rear seat to battery positive and the starter turns right over, no problems. So I know the starter is fine. |
I take this to mean you connected the #50 starter solenoid wire directly to the positive (+) battery terminal and the starter cranked the engine just fine. This confirms your starter is working as long as you get enough current to the starter solenoid #50 terminal.
| mk1978 wrote: |
| I haven't turned up any good troubleshooting sequences for the later Bugs as far as determining if it's just the switch. |
Do you have a digital multimeter? If you don't have one you should buy or borrow one. It is indispensable when it comes to VW electrical problems.
Start by measuring the DC voltage at the battery terminals. A fully charged batter should read 12.6v.
Move to the fuse box. 2 or 3 of the fuses will have voltage while the ignition is OFF. What is your voltage reading here. With new wires the voltage reading here will probably be 12.5v due to the resistance in the length of wire from the battery to the fuse box. Any less than this and your have high resistance in the wires/connections. If it is below 12.0v you should take some time to clean up the wire connections to reduce the voltage loss.
Move to the underside of the ignition switch. Look for the plug at the bottom end of the ignition switch assembly. ID the solid red #30 wire running into the plug. This red wire comes from one of those fuses you just measured at the fuse box. Insert your MM probe into the space around the wire so you can measure the voltage on the wire. The voltage reading here should be almost identical to the fuse box reading as the wire run is short. If the voltage has dropped further it means more resistance from old wires/connectors.
Turn the key to the ON/RUN position and test for voltage on the solid black #15 wire at the ignition switch plug. This is the ignition switched 12v circuit that powers many devices. With these devices now powered, the voltage reading should drop a little. This is your new baseline for voltage while the ignition switch is ON.
With the starter solenoid wire under the rear seat disconnected, test for voltage on the #50 red/black wire coming off the ignition switch plug. There should be 0 volts while the key is in the ON/RUN position. When you turn the key to START the ignition switch will power the red/black #50 wire. The voltage reading should be the same as the reading on the black #15 wire. Any difference in voltage is due to internal resistance in the ignition switch.
Move to the rear seat. With the key in the START position, take a voltage measurement at the end of the disconnected #50 wire below the left rear seat. This reading should be only slightly lower than the voltage reading taken at the other end of this #50 wire at the ignition switch plug. If the voltage is more than 0.1v lower it is due to resistance in the wiring/connectors.
Report back all your voltage readings at the different points in the circuit.
From the ignition switch and the end of the #50 wire run the test multiple times to confirm if the voltage is intermittent or varies in the voltage reading. Both indicate a bad connection in the ignition switch or in the wire/connections. If the voltage that makes it to the end of the #50 wire below the rear seat is less than 12.0v or intermittent, the starter will not reliably crank the engine. If the same inconsistent/intermittent pattern is seen at both ends of the #50 wire the problem is internal to the ignition switch.
This is a common problem with decades old switches. If you have an OE VW ignition switch, I would recommend you carefully take the switch apart and rebuilt it by cleaning the contact surfaces. Unfortunately, after the 1970 model the ignition switches were made mostly of plastic. After a couple decades the plastic becomes brittle and will likely break when you attempt to open up the switch.
You could replace the switch with an aftermarket switch but these are notorious for having much smaller contact areas than the OE VW switches. This means they will burn contacts and fail much sooner. You can add relays to the #50, #15 and #X circuits coming off the aftermarket switch to extend the life of these weak internal contacts indefinitely. Such a relay on the #50 circuit is known as a Hard Start Relay (HSR). If you find the voltage at the #50 circuit under the rear seat is consistently low but above 6.0v you can use a Bosch-style HSR under the rear seat to power the starter solenoid directly from the battery. |
Ok this was fun, I should have written down my results but I'm pretty sure I have them by memory:
-battery 13.6V (brand new)
-powered fuses 13.5V
-red wire to switch, key off 13.5V
-black wire at switch, key on 12.6V
-red/black wire at switch, key on RUN or START 0V
I didn't even proceed since obviously if the red/black wire isn't putting anything out that's why I'm getting no/very rare juice (it did turn over twice in 25 tries).
I'm guessing this is a bad switch? thanks for the help, love figuring this stuff out.
Oh btw, since the starter cranks just fine using a jumper from battery I ended up getting the car started, separate post!
thanks again,
Mk
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1977 Beetle ('72 engine)
Last edited by mk1978 on Sat Mar 18, 2023 5:09 pm; edited 1 time in total |
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busdaddy
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Joined: February 12, 2004
Posts: 51153
Location: Surrey B.C. Canada, but thinking of Ukraine
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| Posted: Sat Mar 18, 2023 4:56 pm Post subject: Re: Starting issues/switch troubleshooting |
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| mk1978 wrote: |
| -red/black wire at switch, key on RUN 0V |
How about when the key was turned to start?
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Rust NEVER sleeps and stock never goes out of style.
Please don't PM technical questions, ask your problem in public so everyone can play along. If you think it's too stupid post it here
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mk1978
Samba Member
Joined: November 25, 2022
Posts: 71
Location: Olympia, Wa
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| Posted: Sat Mar 18, 2023 5:08 pm Post subject: Re: Starting issues/switch troubleshooting |
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| busdaddy wrote: |
| mk1978 wrote: |
| -red/black wire at switch, key on RUN 0V |
How about when the key was turned to start? |
Oh I should edit that, it should say START, not run....
0V at the black/red wire on START
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busdaddy
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Location: Surrey B.C. Canada, but thinking of Ukraine
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| Posted: Sat Mar 18, 2023 5:14 pm Post subject: Re: Starting issues/switch troubleshooting |
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Bad switch, or severely worn lock mechanism.
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Rust NEVER sleeps and stock never goes out of style.
Please don't PM technical questions, ask your problem in public so everyone can play along. If you think it's too stupid post it here
Stop dead photo links! Post your photos to The Samba Gallery!
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mk1978
Samba Member
Joined: November 25, 2022
Posts: 71
Location: Olympia, Wa
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| Posted: Sun Mar 19, 2023 8:56 pm Post subject: Re: Starting issues/switch troubleshooting |
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Well I'm ordering a new ignitions switch but today I noticed during my 1st test drive (which was super fun) that turn signals, horn, and wipers are ALL not functioning.
Could this be a switch issue too?
thanks,
Mk
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1977 Beetle ('72 engine) |
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Cusser
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Joined: October 02, 2006
Posts: 31379
Location: Hot Arizona
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| Posted: Mon Mar 20, 2023 8:03 am Post subject: Re: Starting issues/switch troubleshooting |
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| mk1978 wrote: |
Well I'm ordering a new ignitions switch but today I noticed during my 1st test drive (which was super fun) that turn signals, horn, and wipers are ALL not functioning.
Could this be a switch issue too?
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Could be !
Test the circuits for power, and those are all fuse-protected.
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1970 VW (owned since 1972) and 1971 VW Convertible (owned since 1976), second owner of each. The '71 now has the 1835 engine, swapped from the '70. Second owner of each. 1988 Mazda B2200 truck, 1998 Frontier, 2014 Yukon, 2004 Frontier King Cab. All manual transmission except for the Yukon. http://www.thesamba.com/vw/forum/album_page.php?pic_id=335294 http://www.thesamba.com/vw/forum/album_page.php?pic_id=335297 |
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ashman40
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Joined: February 16, 2007
Posts: 15987
Location: North Florida, USA
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| Posted: Mon Mar 20, 2023 1:51 pm Post subject: Re: Starting issues/switch troubleshooting |
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| mk1978 wrote: |
| ashman40 wrote: |
| Start by measuring the DC voltage at the battery terminals. A fully charged batter should read 12.6v. |
Ok this was fun, I should have written down my results but I'm pretty sure I have them by memory:
-battery 13.6V (brand new)
-powered fuses 13.5V
-red wire to switch, key off 13.5V |
The voltage readings here are much higher than expected. I would only expect to see these readings if you just removed the battery from the charger. This is known as a "surface charge" and does not reflect the actual voltage being produced by the battery. Once a small load is placed on the battery (quick attempt to crank the engine), or if left overnight, the battery voltage at the posts should drop to reflect the actual state of charge closer to 12.6v if fully charged.
| mk1978 wrote: |
| -black wire at switch, key on 12.6V |
This is more like it. Once the key was turned to ON the current draw from the different accessories pulled the voltage down to its normal level. 
| mk1978 wrote: |
-red/black wire at switch, key on RUN or START 0V
I'm guessing this is a bad switch? |
Looks like it.
| ashman40 wrote: |
| You could replace the switch with an aftermarket switch but these are notorious for having much smaller contact areas than the OE VW switches. |
| mk1978 wrote: |
| Well I'm ordering a new ignitions switch but today |
If you buy a new aftermarket ignition switch, I highly recommend you add a Bosch-style hard start relay into the #50 circuit below the rear seat. Powered by the battery terminal it will reliably power the starter each time the key is turned to START.
You may also want to add a Bosch-style relay to the #15 (black) wire coming off the ignition switch before it reaches the fuse box. Power it from one of the constant 12v fuses in the fuse box.
Adding relays to these circuits reduces the current that passes thru the ignition switch contacts. This should allow you to run the aftermarket switch for many years.
I also recommend you test the new ignition switch outside the switch lock housing and then test again once you have installed it. There have been a few reports of ignition switches that do not close START contacts when turned to the limit the lock housing allows. This is seen as the switch working outside the housing but does not work once installed. The lock mechanism has a limited range of rotation.
What has sometimes helped when this happens is to gently push/tap the external #50 male terminal further into the plastic housing. This forces the internal contacts closer together so they make firm contact. Be careful not to drive the terminal in too far as you will jam up the internal mechanism.
_________________
AshMan40
---------------------------
'67 Beetle #1 {project car that never made it to the road }
'75 Beetle 1200LS (RHD Japan model) {junked due to frame rot}
'67 Beetle #2 {2019 project car - Wish me luck!} |
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mk1978
Samba Member
Joined: November 25, 2022
Posts: 71
Location: Olympia, Wa
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| Posted: Tue Mar 21, 2023 7:40 pm Post subject: Re: Starting issues/switch troubleshooting |
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| ashman40 wrote: |
| mk1978 wrote: |
| ashman40 wrote: |
| Start by measuring the DC voltage at the battery terminals. A fully charged batter should read 12.6v. |
Ok this was fun, I should have written down my results but I'm pretty sure I have them by memory:
-battery 13.6V (brand new)
-powered fuses 13.5V
-red wire to switch, key off 13.5V |
The voltage readings here are much higher than expected. I would only expect to see these readings if you just removed the battery from the charger. This is known as a "surface charge" and does not reflect the actual voltage being produced by the battery. Once a small load is placed on the battery (quick attempt to crank the engine), or if left overnight, the battery voltage at the posts should drop to reflect the actual state of charge closer to 12.6v if fully charged.
| mk1978 wrote: |
| -black wire at switch, key on 12.6V |
This is more like it. Once the key was turned to ON the current draw from the different accessories pulled the voltage down to its normal level.
| mk1978 wrote: |
-red/black wire at switch, key on RUN or START 0V
I'm guessing this is a bad switch? |
Looks like it.
| ashman40 wrote: |
| You could replace the switch with an aftermarket switch but these are notorious for having much smaller contact areas than the OE VW switches. |
| mk1978 wrote: |
| Well I'm ordering a new ignitions switch but today |
If you buy a new aftermarket ignition switch, I highly recommend you add a Bosch-style hard start relay into the #50 circuit below the rear seat. Powered by the battery terminal it will reliably power the starter each time the key is turned to START.
You may also want to add a Bosch-style relay to the #15 (black) wire coming off the ignition switch before it reaches the fuse box. Power it from one of the constant 12v fuses in the fuse box.
Adding relays to these circuits reduces the current that passes thru the ignition switch contacts. This should allow you to run the aftermarket switch for many years.
I also recommend you test the new ignition switch outside the switch lock housing and then test again once you have installed it. There have been a few reports of ignition switches that do not close START contacts when turned to the limit the lock housing allows. This is seen as the switch working outside the housing but does not work once installed. The lock mechanism has a limited range of rotation.
What has sometimes helped when this happens is to gently push/tap the external #50 male terminal further into the plastic housing. This forces the internal contacts closer together so they make firm contact. Be careful not to drive the terminal in too far as you will jam up the internal mechanism. |
Yes the battery did come off the charger recently.
I am for sure gonna install one of the hard start relays.
In sleuthing around now I'm finding my horn, turn signals, and wipers are all non functioning. I did a quick check at the fuse box with test light just to see what was getting power and the 1st half of the fuses were dead with key on, last half lit up.
I'm gonna replace this switch for sure.
I do have functional headlights, tail lights, brake lights.
Mk
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1977 Beetle ('72 engine) |
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ashman40
Samba Member
Joined: February 16, 2007
Posts: 15987
Location: North Florida, USA
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| Posted: Wed Mar 22, 2023 8:16 am Post subject: Re: Starting issues/switch troubleshooting |
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| mk1978 wrote: |
In sleuthing around now I'm finding my horn, turn signals, and wipers are all non functioning. I did a quick check at the fuse box with test light just to see what was getting power and the 1st half of the fuses were dead with key on, last half lit up.
I do have functional headlights, tail lights, brake lights. |
When things are not working, first thing is to check fuses. Remove all the fuses from the fuse box and clean up the contacts at the ends of the fuses as well as the clips that hold the fuses so you have nice clean connections.
Unlike many other cars, many of the fuses in the Beetle fuse box are powered AFTER the switch rather than before. Specifically, the 2 parking light and 4 headlight fuses are not powered until the switch is turned ON. For the 12-fuse fuse boxes ('71-later) these are fuses #1 ~ #6. You should not expect to get a voltage reading on these fuses until you turn on the headlight switch to the 1st (parking only) or 2nd (parking + headlights) ON position. And only two of the headlight fuses (high or low) will be powered at a time.
Also, fuses #10 ~ #12 are powered from the ignition switch so only have 12v when the key is in the ON/RUN position.
Fuse #7 is a spare.
Fuse #8 & #9 are constant 12v from the battery. There should be 12v at both ends of these fuses at all times.
Fuse #10 is ignition switch powered when key is in the ON/RUN position (not powered when key is turned to START). Wipers are powered from here as well as anything not critical like the fan. The headlights are also powered from the INPUT side of this fuse which means they are not protected by this fuse. Also, when this fuse is not powered (when key is in START position) the headlights will not have power.
Fuse #11 & #12 are ignition switch powered when key is in the ON/RUN and START positions. This is the majority of accessories.
Check the wiring at these fuses to understand which systems is powered by which fuse. VW moved things around over the different years. The horn and brake lights are usually on the same fuse. So that your brake lights work but horn does not suggests a problem with horn wiring.
The ignition coil is powered from the INPUT side of one of these fuses. Again this means the igntion coil is not protected by a fuse. I recommend adding an inline fuse to the ignition coil wire to protect it from shorts.
_________________
AshMan40
---------------------------
'67 Beetle #1 {project car that never made it to the road }
'75 Beetle 1200LS (RHD Japan model) {junked due to frame rot}
'67 Beetle #2 {2019 project car - Wish me luck!} |
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mk1978
Samba Member
Joined: November 25, 2022
Posts: 71
Location: Olympia, Wa
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| Posted: Thu Mar 23, 2023 1:28 pm Post subject: Re: Starting issues/switch troubleshooting |
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| ashman40 wrote: |
| mk1978 wrote: |
In sleuthing around now I'm finding my horn, turn signals, and wipers are all non functioning. I did a quick check at the fuse box with test light just to see what was getting power and the 1st half of the fuses were dead with key on, last half lit up.
I do have functional headlights, tail lights, brake lights. |
When things are not working, first thing is to check fuses. Remove all the fuses from the fuse box and clean up the contacts at the ends of the fuses as well as the clips that hold the fuses so you have nice clean connections.
Unlike many other cars, many of the fuses in the Beetle fuse box are powered AFTER the switch rather than before. Specifically, the 2 parking light and 4 headlight fuses are not powered until the switch is turned ON. For the 12-fuse fuse boxes ('71-later) these are fuses #1 ~ #6. You should not expect to get a voltage reading on these fuses until you turn on the headlight switch to the 1st (parking only) or 2nd (parking + headlights) ON position. And only two of the headlight fuses (high or low) will be powered at a time.
Also, fuses #10 ~ #12 are powered from the ignition switch so only have 12v when the key is in the ON/RUN position.
Fuse #7 is a spare.
Fuse #8 & #9 are constant 12v from the battery. There should be 12v at both ends of these fuses at all times.
Fuse #10 is ignition switch powered when key is in the ON/RUN position (not powered when key is turned to START). Wipers are powered from here as well as anything not critical like the fan. The headlights are also powered from the INPUT side of this fuse which means they are not protected by this fuse. Also, when this fuse is not powered (when key is in START position) the headlights will not have power.
Fuse #11 & #12 are ignition switch powered when key is in the ON/RUN and START positions. This is the majority of accessories.
Check the wiring at these fuses to understand which systems is powered by which fuse. VW moved things around over the different years. The horn and brake lights are usually on the same fuse. So that your brake lights work but horn does not suggests a problem with horn wiring.
The ignition coil is powered from the INPUT side of one of these fuses. Again this means the igntion coil is not protected by a fuse. I recommend adding an inline fuse to the ignition coil wire to protect it from shorts. |
Ok more great info, gonna get checking all this out this week.
I am planning on replacing all the fuses anyway, they all look old & my owners manual tells me they should all be white except for 2 red ones.....ALL of mine are red!
thanks,
Mk
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1977 Beetle ('72 engine) |
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ashman40
Samba Member
Joined: February 16, 2007
Posts: 15987
Location: North Florida, USA
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| Posted: Sun Mar 26, 2023 9:09 am Post subject: Re: Starting issues/switch troubleshooting |
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| mk1978 wrote: |
| I am planning on replacing all the fuses anyway, they all look old |
The GBC style fuses in Beetles are just strips of metal. Nothing that really changes unless they blow/burn up. You just need to polish the ends with some sandpaper so they can make a good electrical connection. Whiles you are at it clean the fuse clips and you are as good as new.
| mk1978 wrote: |
| my owners manual tells me they should all be white except for 2 red ones.....ALL of mine are red! |
'76-'79 Beetles had a red (16A) fuse in the #9 and #10 positions. All other fuses are white (8A). Sounds like the PO was lazy and just stocked up on 16A fuses. Using fuses rated higher than the circuit was designed for is asking for melted wires, or worse a fire!
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AshMan40
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'67 Beetle #1 {project car that never made it to the road }
'75 Beetle 1200LS (RHD Japan model) {junked due to frame rot}
'67 Beetle #2 {2019 project car - Wish me luck!} |
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