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trep01 Samba Member
Joined: June 28, 2004 Posts: 136 Location: Sarasota, Fl
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Posted: Sat Jan 28, 2023 10:20 am Post subject: '79 Headlights Not Working |
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Headlights are not working. Running lights are. I checked the fuses designated to the low and high beams and the fuse block is getting no power for these circuits. When I jump these circuits the lights come on. I've been studying wiring diagrams for two days and cannot figure out the issue. Could it be the low beam relay? Where does the power come from that runs into the fuse block for these circuits? Could it be the switch even though the running lights and dash dimmer work? Any help would be appreciated. Thank you. |
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busdaddy Samba Member
Joined: February 12, 2004 Posts: 51128 Location: Surrey B.C. Canada, but thinking of Ukraine
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Posted: Sat Jan 28, 2023 11:09 am Post subject: Re: '79 Headlights Not Working |
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You have the ignition switch on, right? _________________ 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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Слава Україні! |
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trep01 Samba Member
Joined: June 28, 2004 Posts: 136 Location: Sarasota, Fl
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Posted: Sat Jan 28, 2023 11:46 am Post subject: Re: '79 Headlights Not Working |
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Indeed I do. Also, now my backup lights aren't working, either. |
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busdaddy Samba Member
Joined: February 12, 2004 Posts: 51128 Location: Surrey B.C. Canada, but thinking of Ukraine
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Posted: Sat Jan 28, 2023 11:57 am Post subject: Re: '79 Headlights Not Working |
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Power comes from the ignition switch to terminal X n the headlight switch, it stops by the fuse box but isn't fused, but there is a connection on the bus bar. From the headlight switch's terminal #56 it goes to the relay and then on to the individual headlight fuses.
Check for power at 56 on the relay and then work back up the chain, headlight circuitry depicted around current track 16 here: https://www.thesamba.com/vw/archives/info/wiring/76-79113wiring.jpg
X also powers the wipers, do they work? _________________ 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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sjbartnik Samba Member
Joined: September 01, 2011 Posts: 5994 Location: Brooklyn
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Posted: Sat Jan 28, 2023 11:58 am Post subject: Re: '79 Headlights Not Working |
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OK so the power for the headlights does not come from the same source as that for the running lights. Running lights are powered by a hot wire (30) to the headlight switch which gives them power all the time.
Headlight power comes to the switch from the X circuit. The X circuit into the headlight switch only gets power when the ignition switch is turned on.
So, you get your voltmeter on the back of the headlight switch, you turn the ignition on and you measure for 12v at X terminal. If you don't have it, you trace back to the ignition switch.
If you do have it then you turn the switch on and check for 12V on the 56 terminal (white/black wire). That sends power to the hi/lo beam relay. If you have 12v out on 56, switch is good. If not, switch is bad.
If you have 12v into the relay on 56 but no 12v out on either 56a (high beam, white wire) or 56b (low beam, yellow wire), then relay is bad.
Backup lights not working is completely unrelated. Backup lights are powered by a connector on terminal 15 of the ignition coil. Power goes from coil through an inline fuse to the switch on the transmission, then from the other side of the switch to the lights. Check for blown or corroded fuse. If fuse blows again after replacement, you have a short somewhere in that simple circuit, so trace it out.
EDIT: Backup lights *could* possibly be related if in fact the ignition switch is bad and is not putting 12v out on X and 15 when switched on. But in that case the car would not run. Does it run? _________________ 1965 Volkswagen 1500 Variant S
2000 Kawasaki W650 |
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trep01 Samba Member
Joined: June 28, 2004 Posts: 136 Location: Sarasota, Fl
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Posted: Sat Jan 28, 2023 2:27 pm Post subject: Re: '79 Headlights Not Working |
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Thanks for the replies. Car runs and the wipers work. I checked the in-line on running to the coil and the fuse was good. I cleaned the inline housing connections to make sure there was a good connection and the backup lights still don't wonk. Also noticed that the license plate light is also out now. The gremlins are attaching from every direction. I'll remove the headlight switch and run the test. Thanks again.... |
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trep01 Samba Member
Joined: June 28, 2004 Posts: 136 Location: Sarasota, Fl
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Posted: Sat Jan 28, 2023 2:50 pm Post subject: Re: '79 Headlights Not Working |
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I have 12 volt at the switch when the key in turned on. Looking at the Bently manual I can't really tell where the relay is. I know it's on the back of the fuse bank, but what reley is it? |
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sjbartnik Samba Member
Joined: September 01, 2011 Posts: 5994 Location: Brooklyn
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Posted: Sat Jan 28, 2023 3:16 pm Post subject: Re: '79 Headlights Not Working |
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For the backup lights, next step would be to test the switch. It's a simple open/close switch. With the trans in any gear except reverse and the key on, you should have 12v at one of the terminals on the switch (the one connected to terminal 15 on the coil). When you put the trans in reverse, that closes the switch and then you should see 12v out on the other terminal. If not, switch is bad.
If so, problem is elsewhere. I believe the wire runs from the switch to a splitter connector somewhere in the engine compartment, perhaps behind the tar paper on the firewall, that sends the 12v to each backup light. I believe there are other connections in that connector for taillights etc so that may be a place to look for your license light issue too. The license light is powered off of one of the taillights.
Of course for the license light it could just be that the bulb is burned out.
Same could be true for the backup lights but unlikely for both to burn out at the same time. _________________ 1965 Volkswagen 1500 Variant S
2000 Kawasaki W650 |
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sjbartnik Samba Member
Joined: September 01, 2011 Posts: 5994 Location: Brooklyn
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Posted: Sat Jan 28, 2023 3:18 pm Post subject: Re: '79 Headlights Not Working |
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trep01 wrote: |
I have 12 volt at the switch when the key in turned on. Looking at the Bently manual I can't really tell where the relay is. I know it's on the back of the fuse bank, but what reley is it? |
It's the one that has the fat white and yellow wires going to it. Should be able to trace the wires from the headlight fuses right back to it. _________________ 1965 Volkswagen 1500 Variant S
2000 Kawasaki W650 |
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busdaddy Samba Member
Joined: February 12, 2004 Posts: 51128 Location: Surrey B.C. Canada, but thinking of Ukraine
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Posted: Sat Jan 28, 2023 3:19 pm Post subject: Re: '79 Headlights Not Working |
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There's only 3, one is a little 1" cube, that's the key buzzer, the signal flasher is usually 1" x 1" x 2" and black, the headlight relay is usually 1.5" x 1.5" and silver.
_________________ 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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ashman40 Samba Member
Joined: February 16, 2007 Posts: 15982 Location: North Florida, USA
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Posted: Tue Jan 31, 2023 1:25 pm Post subject: Re: '79 Headlights Not Working |
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trep01 wrote: |
Headlights are not working. Running lights are. I checked the fuses designated to the low and high beams and the fuse block is getting no power for these circuits. |
Testing the headlight fuses with the headlight switch OFF will always result in zero volts at the headlight fuses. The four (4) headlight fuses are placed AFTER the headlight switch and the dimmer relay in the circuit. The headlight switch and relay need to be ON and passing current before one pair of the headlight fuses will have power.
trep01 wrote: |
When I jump these circuits the lights come on. I've been studying wiring diagrams for two days and cannot figure out the issue. Could it be the low beam relay? Where does the power come from that runs into the fuse block for these circuits? |
In '79 the headlight power starts from the "X" circuit (black/yellow wire) coming off the ignition switch. This ignition switch black/yellow wire runs to fuse #10 in the fuse box. Another black/yellow wire daisy chains and runs to the headlight switch "X" terminal. The headlight switch is powered from the unprotected (input) side of fuse #10. This means even if you remove fuse #10 the headlight switch "X" terminal will still be powered by the black/yellow wire.
When you pull the headlight switch fully ON (2nd ON position) the black/yellow wire will now power the white/black wire running from terminal #56 to the dimmer relay. The dimmer relay determines whether the low or high beams are powered. It is a latching relay which means momentarily powering the relay will cause the output to switch and "latch" into position. It remains there until the relay is next powered and the output switches and latches to the new output. The dimmer relay is only powered momentarily while the dimmer switch in the turn signal lever is pulled. The single white wire from the dimmer relay runs to the two high beam fuses. The single yellow wire runs to the two low beam fuses.
If you happen to have a 5-prong dimmer relay it will have an extra #30 terminal which must be powered for the headlights to work. Check for this. The normal wiring has a red wire running from the #30 terminal of the dimmer relay to one of the constant 12v powered fuses in the fuse box. This red wire is powered from the INPUT side of the fuse so it does not add the load of the headlights to one of the fuses.
The dimmer relay only powers a pair of headlight fuses at a time.
Using your VM or 12v test lamp, test for voltage at each step of the circuit. Start from the ignition switch, to the fuse box, to the headlight switch, to the dimmer relay, to the fuse box and then to the headlights.
trep01 wrote: |
Could it be the switch even though the running lights and dash dimmer work? |
The running/parking lights are powered by the red #30 wire running from the fuse box to the headlight switch. The current coming into the #30 terminal of the headlight switch never touches the headlight circuit. The headlights are powered from the #X circuit. The parking lights and speedometer illumination lamps are powered by the #30 circuit. This means the parking lights may work fine while the headlights are inoperable. They are completely separate circuits that diverge at the fuse box. The parking lights are powered from the battery. The headlights are powered by the black/yellow (X) circuit which is powered by the ignition switch being ON. This is a separate circuit from the black #15 ignition switched circuit. You will find that when the ignition key is turned to START the headlights and wipers are unpowered while the rest of the ignition circuit remains powered. _________________ 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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vwoldbug Samba Member
Joined: January 28, 2009 Posts: 1214 Location: Ohio
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Posted: Tue Jan 31, 2023 3:52 pm Post subject: Re: '79 Headlights Not Working |
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Follow these guys and please let us know . Good luck |
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trep01 Samba Member
Joined: June 28, 2004 Posts: 136 Location: Sarasota, Fl
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Posted: Tue Jan 31, 2023 4:50 pm Post subject: Re: '79 Headlights Not Working |
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Thank you for the responses. I'll take this into consideration as I continue to chase this issue down. I appreciate your time and will post my progress. |
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ashman40 Samba Member
Joined: February 16, 2007 Posts: 15982 Location: North Florida, USA
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Posted: Wed Feb 01, 2023 3:06 pm Post subject: Re: '79 Headlights Not Working |
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Here is a simplified headlight circuit diagram from Speedy Jim’s site:
_________________ 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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trep01 Samba Member
Joined: June 28, 2004 Posts: 136 Location: Sarasota, Fl
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Posted: Thu Feb 02, 2023 2:06 pm Post subject: Re: '79 Headlights Not Working |
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Thanks for the wiring diagram. I traced it all down to a bad relay. I swapped out for a new one and now have headlights. However, the high-beams are not working. Back to the multi-tester. |
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busdaddy Samba Member
Joined: February 12, 2004 Posts: 51128 Location: Surrey B.C. Canada, but thinking of Ukraine
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Posted: Thu Feb 02, 2023 3:34 pm Post subject: Re: '79 Headlights Not Working |
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If the new relay has a #30 terminal you'll have to jump it to #56, or power it from a red circuit on the fuse box. Most originals on USA cars don't have that terminal and the one style for the whole world replacements do, it won't change beams without it powered. _________________ 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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trep01 Samba Member
Joined: June 28, 2004 Posts: 136 Location: Sarasota, Fl
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Posted: Thu Feb 02, 2023 6:04 pm Post subject: Re: '79 Headlights Not Working |
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That is exactly the issue. Thank you |
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