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vamram 
Samba Member
Joined: March 08, 2012
Posts: 7307
Location: NOVA
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 Posted: Wed Nov 07, 2018 5:04 pm Post subject: Horn Stops Working When Lights are On -FIXED |
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Hello All-
I'm trying to determine if my battery is dying or my alternator/regulator. When the lights and radio are on, the horn often stops working. If I turn the lights off, just the parking lights, it then works, although it takes a second to respond. I also noticed tonight that the alternator light comes on dimly during this when I press the horn button w/the lights and wipers on.
Is this a dying batter - 3 years old - or alternator?
Thanks,
Victor
_________________
Eventually, "we are what we pretend to be.’”
Give peace a chance - Stop Russian-Soviet Aggression!!
'74 Super 9/16 - present, in refurb process.
'73 Super - 6/18 - Present - Daily Driver!
'75 Super Le Grande...waiting it's turn in line behind '74.
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Last edited by vamram on Mon Feb 04, 2019 5:42 pm; edited 1 time in total |
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busdaddy
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Joined: February 12, 2004
Posts: 51156
Location: Surrey B.C. Canada, but thinking of Ukraine
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| Posted: Wed Nov 07, 2018 5:38 pm Post subject: Re: Horn Stops Working When Lights are On |
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Sounds like the horn is getting weak and telling you it's time to hook up a volt/ohm meter and watch what's happening in your electrical system. Drive around with it connected at the front somewhere one day, and directly to the battery the next and compare the results, it could be a weak charging system, or maybe a bad connection at the fuse box or starter, testing front and back will narrow it down.
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ashman40
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Joined: February 16, 2007
Posts: 15987
Location: North Florida, USA
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| Posted: Wed Nov 07, 2018 6:19 pm Post subject: Re: Horn Stops Working When Lights are On |
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Yup. Measure voltage drop at different points.
Start at battery where fully charged it should read 12.6v between the battery posts.
At the front (fuse box) you should expect a small voltage drop. If the wires were NEW you could expect as little as 0.1v drop in the measurements; battery to front. But with 40yr old wires you should expect to see up to 0.5v drop.
Also check the voltage difference at both the battery and front when the engine is running to see what the charging system us producing. @2100rpm you should read at least 13.8v at the battery.
Post your voltage readings.
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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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vamram
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Joined: March 08, 2012
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Location: NOVA
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| Posted: Wed Nov 07, 2018 7:22 pm Post subject: Re: Horn Stops Working When Lights are On |
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Thanks - I will do the tests at the battery and elsewhere Saturday and report back. Any specific post I should check at the fuse box? This is a '74 Super Beetle.
Just one other note, it's been progressively getting worse, and I did have to charge the battery overnight back in September. It was dead as a door nail when I tried to start it the first time back from a trip after after the car sat for 10 days.
_________________
Eventually, "we are what we pretend to be.’”
Give peace a chance - Stop Russian-Soviet Aggression!!
'74 Super 9/16 - present, in refurb process.
'73 Super - 6/18 - Present - Daily Driver!
'75 Super Le Grande...waiting it's turn in line behind '74.
Click to view image
Save the Supers!! |
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ashman40
Samba Member
Joined: February 16, 2007
Posts: 15987
Location: North Florida, USA
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| Posted: Thu Nov 08, 2018 6:36 am Post subject: Re: Horn Stops Working When Lights are On |
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| vamram wrote: |
| Any specific post I should check at the fuse box? This is a '74 Super Beetle. |
Two fuses are constant 12v. These should be fuses #8 and #9. They are directly connected to the battery positive terminal. Ideally, they should be EXACTLY the same voltage as the battery as there is nothing between them and the battery.
| vamram wrote: |
| Just one other note, it's been progressively getting worse, and I did have to charge the battery overnight back in September. It was dead as a door nail when I tried to start it the first time back from a trip after after the car sat for 10 days. |
It really is starting to sound like you may need a new battery.
How old is your battery? Normal lead-acid batteries have a reasonable life expectancy of around 4-5yrs. If it is older than that you should be window shopping for a new battery.
Normal lead-acid batteries do not take well to being completely discharged. They will no longer be able to hold the same charge. If your battery is close to 5yrs old that discharge could have been "the last nail in its coffin."
Take your battery to your FLAPS and have them charge then test it.
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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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vamram
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| Posted: Thu Nov 08, 2018 7:54 am Post subject: Re: Horn Stops Working When Lights are On |
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The battery is at least 2+years old because that's how long I've had the car. I have no idea how long the previous owner had it.
I've had to charge this battery several times since buying the car, the 1st time because the wiring was so bad in the Bug that it wasn't getting properly charged by the alternator. The latest was after returning from vacation in September.
I'm thinking of calling AAA to check it as I have their battery replacement service with the premium plan and have found that they're pretty good at checking the battery, more reliable for this than the Advanced Auto equipment and counter guys.
_________________
Eventually, "we are what we pretend to be.’”
Give peace a chance - Stop Russian-Soviet Aggression!!
'74 Super 9/16 - present, in refurb process.
'73 Super - 6/18 - Present - Daily Driver!
'75 Super Le Grande...waiting it's turn in line behind '74.
Click to view image
Save the Supers!! |
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vamram
Samba Member
Joined: March 08, 2012
Posts: 7307
Location: NOVA
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| Posted: Sun Nov 11, 2018 10:32 am Post subject: Re: Horn Stops Working When Lights are On |
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Ok, well, here are the readings w/the car running.
- 13.4-7 at the battery
- 13.2-4 at fuse post #8
Car running, lights and blinkers on:
- 12.2+ at battery posts
- 11.2+ at fuse posts #8
Car OFF: 12.2 at the battery posts.
_________________
Eventually, "we are what we pretend to be.’”
Give peace a chance - Stop Russian-Soviet Aggression!!
'74 Super 9/16 - present, in refurb process.
'73 Super - 6/18 - Present - Daily Driver!
'75 Super Le Grande...waiting it's turn in line behind '74.
Click to view image
Save the Supers!! |
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Cusser
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Posts: 31385
Location: Hot Arizona
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| Posted: Sun Nov 11, 2018 11:18 am Post subject: Re: Horn Stops Working When Lights are On |
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| vamram wrote: |
Car running, lights and blinkers on:
- 12.2+ at battery posts
- 11.2+ at fuse posts #8
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I went out and plugged my digital voltmeter into the accessory cigarette lighter socket on my 1971 VW with generator. I started engine, revved up the engine, got 14.0 volt reading; then keeping rpm steady I turned on headlights, reading dropped to 13.0 volts. When I turned on turn signals dropped a few tenths more.
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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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vamram
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| Posted: Sun Nov 11, 2018 12:12 pm Post subject: Re: Horn Stops Working When Lights are On |
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Cusser - does that mean my voltages are too low or that they're ok? Also, if mine are within acceptable limits, what would explain my original question?
_________________
Eventually, "we are what we pretend to be.’”
Give peace a chance - Stop Russian-Soviet Aggression!!
'74 Super 9/16 - present, in refurb process.
'73 Super - 6/18 - Present - Daily Driver!
'75 Super Le Grande...waiting it's turn in line behind '74.
Click to view image
Save the Supers!! |
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vamram
Samba Member
Joined: March 08, 2012
Posts: 7307
Location: NOVA
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| Posted: Sun Nov 11, 2018 12:37 pm Post subject: Re: Horn Stops Working When Lights are On |
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BTW - i took these readings in my driveway immediately following a 45-50 mile cruise, without having turned the car off yet.
| vamram wrote: |
Ok, well, here are the readings w/the car running.
- 13.4-7 at the battery
- 13.2-4 at fuse post #8
Car running, lights and blinkers on:
- 12.2+ at battery posts
- 11.2+ at fuse posts #8
Car OFF: 12.2 at the battery posts. |
_________________
Eventually, "we are what we pretend to be.’”
Give peace a chance - Stop Russian-Soviet Aggression!!
'74 Super 9/16 - present, in refurb process.
'73 Super - 6/18 - Present - Daily Driver!
'75 Super Le Grande...waiting it's turn in line behind '74.
Click to view image
Save the Supers!! |
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ashman40
Samba Member
Joined: February 16, 2007
Posts: 15987
Location: North Florida, USA
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| Posted: Sun Nov 11, 2018 2:28 pm Post subject: Re: Horn Stops Working When Lights are On |
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| vamram wrote: |
BTW - i took these readings in my driveway immediately following a 45-50 mile cruise, without having turned the car off yet.
| vamram wrote: |
Ok, well, here are the readings w/the car running.
- 13.4-7 at the battery
- 13.2-4 at fuse post #8
Car running, lights and blinkers on:
- 12.2+ at battery posts
- 11.2+ at fuse posts #8
Car OFF: 12.2 at the battery posts. |
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Hmm, immediately following a 50mi cruise I'd expect the battery would be fully charged. 12.2v AT the battery posts is only around 50% state of charge.
The problem is you cannot rate the ability of the charging system while measuring voltage with a discharged battery, which is what you have. Even the charging voltage of 13.4-13.7v is LOW but it could be low BECAUSE you have a discharged battery.
You either need to:
1) Take the battery and get it "fully charged" before testing the voltage readings. At 100% state of charge the battery should maintain 12.6v at the posts.
2) Take the charging system (alternator/generator) to the FLAPS and have them test it on a bench tester.
3) Put a fully charged stand-in battery in place of yours and run the charging system tests again.
_________________
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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vamram
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Posts: 7307
Location: NOVA
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| Posted: Sun Nov 11, 2018 3:56 pm Post subject: Re: Horn Stops Working When Lights are On |
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Thanks Ashman. I'll put it on a trickle charger tonight.
_________________
Eventually, "we are what we pretend to be.’”
Give peace a chance - Stop Russian-Soviet Aggression!!
'74 Super 9/16 - present, in refurb process.
'73 Super - 6/18 - Present - Daily Driver!
'75 Super Le Grande...waiting it's turn in line behind '74.
Click to view image
Save the Supers!! |
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glutamodo
The Android
Joined: July 13, 2004
Posts: 26325
Location: Douglas, WY
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| Posted: Sun Nov 11, 2018 8:00 pm Post subject: Re: Horn Stops Working When Lights are On |
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Resting Voltage tests are good, but I still remember back in the day using a battery fluid specific gravity tester to suss out bad cell(s) when the battery otherwise seemed to charge OK. I probably still have one or two of those testers buried away in seldom looked at toolboxes.
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vamram
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| Posted: Mon Nov 12, 2018 9:35 am Post subject: Re: Horn Stops Working When Lights are On |
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The DieHard charger reports it's complete. Immediately after disconnecting the charger, the reading at the posts is 12.56v, car turned off.
Am I right that this is a sign of a bad battery?
_________________
Eventually, "we are what we pretend to be.’”
Give peace a chance - Stop Russian-Soviet Aggression!!
'74 Super 9/16 - present, in refurb process.
'73 Super - 6/18 - Present - Daily Driver!
'75 Super Le Grande...waiting it's turn in line behind '74.
Click to view image
Save the Supers!! |
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Cusser
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Joined: October 02, 2006
Posts: 31385
Location: Hot Arizona
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| Posted: Mon Nov 12, 2018 4:27 pm Post subject: Re: Horn Stops Working When Lights are On |
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| vamram wrote: |
The DieHard charger reports it's complete. Immediately after disconnecting the charger, the reading at the posts is 12.56v, car turned off.
Am I right that this is a sign of a bad battery? |
Not really - must be checked UNDER LOAD.
_________________
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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scottyrocks
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| Posted: Mon Nov 12, 2018 7:18 pm Post subject: Re: Horn Stops Working When Lights are On |
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My horn ('63, 6v) did not work much when I got the car (old wiring). I spliced in a horn relay, and then it worked.
My directionals were iffy, as well. If the headlights were on, the directionals wouldn't flash. I replaced the ancient relay with a modern electronic one from WW, and the directionals work like a modern car, headlights off or on.
Cleaning up all the electrical contacts helped, too.
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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 Nov 12, 2018 11:09 pm Post subject: Re: Horn Stops Working When Lights are On |
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| vamram wrote: |
The DieHard charger reports it's complete. Immediately after disconnecting the charger, the reading at the posts is 12.56v, car turned off.
Am I right that this is a sign of a bad battery? |
This doesn't sound right. I'd expect there to be a surface voltage close to the charging voltage. 12.56v sounds too low if you had just turned off the charger. Your charger should be outputting around 14.0v. As soon as you turn off the charger the voltage at the battery posts should be very close to 14.0v. This is why some mistakenly think their battery is holding a charge when they measure the voltage right after charging. You should apply a load to the battery (crank the engine once) and see if the battery will maintain the charge. This load remove the surface charge and you get a view of the actual battery voltage. If the voltage drops below 12.6v then the battery isn't holding the charge.
Also check the voltage at the battery posts WHILE cranking. If the voltage drops too low (below 10.0v) the battery can't take the load and is bad.
If your static battery voltage is close to 12.6v, start the engine and rev to around 2100rpm. Take a voltage reading at the battery and see if the charging system output is closer to 13.8v.
_________________
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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vamram
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Posts: 7307
Location: NOVA
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| Posted: Tue Nov 13, 2018 4:04 pm Post subject: Re: Horn Stops Working When Lights are On |
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Ashman - it reads 13.26v at the battery at 2.5k RPM, headlights on.
Results at advanced Auto were 13.4 under load, brights on fan at full, rpms over 2k. 14.1 no load. 12.56 car off.
Under load, the horn won't work and alternator light glows red while I press the button. But then it does work. Driving me nuts.
_________________
Eventually, "we are what we pretend to be.’”
Give peace a chance - Stop Russian-Soviet Aggression!!
'74 Super 9/16 - present, in refurb process.
'73 Super - 6/18 - Present - Daily Driver!
'75 Super Le Grande...waiting it's turn in line behind '74.
Click to view image
Save the Supers!! |
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vamram
Samba Member
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Posts: 7307
Location: NOVA
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| Posted: Tue Nov 13, 2018 8:20 pm Post subject: Re: Horn Stops Working When Lights are On |
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Alternator light also glows while driving when I press the brake pedal.
_________________
Eventually, "we are what we pretend to be.’”
Give peace a chance - Stop Russian-Soviet Aggression!!
'74 Super 9/16 - present, in refurb process.
'73 Super - 6/18 - Present - Daily Driver!
'75 Super Le Grande...waiting it's turn in line behind '74.
Click to view image
Save the Supers!! |
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vamram
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Posts: 7307
Location: NOVA
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| Posted: Wed Nov 14, 2018 6:20 am Post subject: Re: Horn Stops Working When Lights are On |
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So i plugged it into the DieHard charger again last night around 8 p.m., on the standard 2-amp trickle setting and left it overnight. Per the readout on the charger this morning it was 100%.
I did the horn test as I drove away from the house (good morning neighbors).
By the time I got to work, the horn was back to its now-normal dying self of not sounding, or starting low and then working itself to a full beeeeeEEEEP.
I'm starting to think it's the charging system - alternator and/or regulator.
_________________
Eventually, "we are what we pretend to be.’”
Give peace a chance - Stop Russian-Soviet Aggression!!
'74 Super 9/16 - present, in refurb process.
'73 Super - 6/18 - Present - Daily Driver!
'75 Super Le Grande...waiting it's turn in line behind '74.
Click to view image
Save the Supers!! |
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