Running Lights and Turn Signals Acting up

[Manfreds78bay]

1978 FI 2.0 Camper

I was sorting out some issues with my reverse lights and license plate light and now I'm getting some really strange behavior.

The fuse holder for the back up lights seemed to have gone bad. I put in a spare and it seemed to fix the problem. The license plate light had a bad ground. I Also the right side marker light was not working. It also a bad ground.

I don't know what I did but now I'm experiencing the following issues.

Lights on:

Rear left running light and turn signal comes on at the same time. Left rear turn signal does not flash. Right rear lights seem to work fine. Both brake lights work fine. Both front turn signals flash at the same time when trying to use the left turn signals

Lights off

Brake lights work fine. When using the left turn signal the left rear side mark light flashes at the same time as the left rear turn signal. The right rear turn signal works fine. The front turn signals do not flash.

I didn't have any issues with the lights besides the revers lights and license plate light.

I've pulled both rear lights and verified the side marker lights have their own ground and the rear lights all ground to the rear of the light housing on both sides. I don't see any crossed wires.

Any help would be great
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1978 2.0L FI Campmobile

1982 AMC Eagle SX4 4.2L FI

[telford dorr]

Sounds like you have a bad ground at the left rear light fixture, so the turn signal is grounding through the tail light circuit.
_________________
'71 panel, now with FI
'Experience' is the ability to recognize a mistake when you're making it again - Franklin P. Jones
In theory, theory works in practice; in practice, it doesn't - William T. Harbaugh
When you're dead, you don't know you're dead. The pain is only felt by others.
Same thing happens when you're stupid. - Philippe Geluck
More VW electrical at http://telforddorr.com/ (available 9am to 9pm PST)

[Manfreds78bay]

[telford dorr]

[SGKent]

What Telford is saying is that you are missing a grounding wire on that housing. The brown wire goes to a screw on the body of the bus. That is the return path for the electricity.

When you get things working semi right be sure to look at the emergency switch with the battery disconnected because that switch comes apart almost 100% of the time on a late bay and causes all kind of problems in the turn signal circuit.

Right now your problem however is you need to add that brown ground wire.



.
_________________
“Most people don’t know what they’re doing, and a lot of them are really good at it.” - George Carlin

[Manfreds78bay]

[Manfreds78bay]

[Manfreds78bay]

Worked on it for an hour or so, still could not figure out where the bad ground is.

I turned on the lights with the key off.

I disconnected all the body grounds in the engine compartment one at a time to see if anything would cause the left turn signal to shut off. The only time it would shut off is when I removed the ground from the left rear light bracket (the thing that holds all the bulbs). Of course this would cause the running light to shut off as well.

So one thing that I didn't tell you is I'm running all LED lights. I put in all standard bulbs to see if I got any difference. It didn't.

However, I did notice some strange behavior. When I disconnected the ground from the left bulb bracket with the LED lights plugged in, the running red light had some voltage running through it. There is a very faint glow only coming through the red running light.

I'm not sure how this is possible since there is no ground connected to it at all. So what does this tell me? The running light is grounding some place else? Would a hole in the plastic allowing the wire to touch the frame some how cause this faint glow?

If this is the case, could this bad ground through the running light cause my turn signal to come on?
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1978 2.0L FI Campmobile

1982 AMC Eagle SX4 4.2L FI

[lil-jinx]

that faint glow is telling you that the light you pulled the ground off of is now useing that lights circuit as a ground.many led light are polarized pos to pos neg to neg.
_________________
https://www.thesamba.com/vw/forum/viewtopic.php?t=620186
https://www.thesamba.com/vw/forum/viewtopic.php?t=668799
1974 Bay Westfalia. she likes to be called Ethel.
1968 Dune Buggy
1974 parts bus
A smart man learns from his mistakes,a very smart man learns from other's mistakes.

[Manfreds78bay]

[telford dorr]

You have a bunch of lamps (tail, turn, stop, backup) all mounted in one housing, all sharing the same ground connection. If that ground were to become disconnected, then the power to one lamp (say the tail lamp, for example) will travel through that lamp to the lamp holder frame, then backwards through the other lamps (for example, the stop lamp) then through its wire to the stop lamp on the other side, then through that lamp to ground. It will also travel through the backup lamp, then through the wire to the other backup lamp, through that lamp to ground, etc. It becomes a bit of a convoluted path through multiple lamps to ground. Thus, the original tail lamp will light (but not as brightly as normal, because of all of the other lamps stealing some of the power). You may even see light from the other lamps.

Now with LEDs, it's a little different as, unlike filament type bulbs, LEDs generally pass current in only one direction. Thus, the other lamps in the housing will become reverse biased, and won't pass current (unless they break down and fail internally, or the mfg. put rectifier or protection diodes in the lamp assembly).

Strange fact: LEDs are photo-sensitive: if you shine a bright light (like the sun) on an LED, it will generate a voltage that you can measure with a meter. Different color LEDs have different sensitivities to light. FWIW...
_________________
'71 panel, now with FI
'Experience' is the ability to recognize a mistake when you're making it again - Franklin P. Jones
In theory, theory works in practice; in practice, it doesn't - William T. Harbaugh
When you're dead, you don't know you're dead. The pain is only felt by others.
Same thing happens when you're stupid. - Philippe Geluck
More VW electrical at http://telforddorr.com/ (available 9am to 9pm PST)

[lil-jinx]

with the light on and you pulled the ground,the power going to the light tried to find another path to ground,it would travel into the metal housing that holds all the bulbs,then it would enter 1 of the bulbs thru the ground side of that bulb and travel out thru the pos side of the bulb and travel up the wire until it entered the other bulb [the 1 that's glowing]then it would go to ground at that light turning that light on at half power because now you have two lights hooked in a series circuit.when you turn the lights on you take away that path to ground,so it keeps traveling looking for a ground and finds it at your front right signal.
keep looking for a faulty ground clean all the connections,all the bulb sockets.
do it 1 light at at time until your 100% sure it,s making a good connection then move onto the next 1,take your time.
Don't let it drive you nuts,good luck.
_________________
https://www.thesamba.com/vw/forum/viewtopic.php?t=620186
https://www.thesamba.com/vw/forum/viewtopic.php?t=668799
1974 Bay Westfalia. she likes to be called Ethel.
1968 Dune Buggy
1974 parts bus
A smart man learns from his mistakes,a very smart man learns from other's mistakes.

[Manfreds78bay]

Okay I finally got back around to troubleshooting this issue. I couldn't find a bad ground connection I start pulling the bulbs and making sure everything was clean and tight. Still having the same issue.

So here is a new development.

If I pull the second fuse from the left, which is for the right rear tale light, license plate and right rear side marker lights, I get the following condition

1. Lights OFF, left running light and turn signal light work as they should. Front turn signal does not work

2. Lights OFF, right turn signal works as it should. Front signal does not work

3. Lights ON, left rear turn signal and running light work as they should. Both front turn signals blink at the same time

4. Light ON, Right rear turn signal works as it should. Front turn signal does not work.

I think I've narrowed down the issue to the #2 circuit. Some how my rear left light is getting power from my right rear light.

I removed the plastic from the wire harness that connects the right and left lights. All the wires look fine.
_________________
1978 2.0L FI Campmobile

1982 AMC Eagle SX4 4.2L FI

[lil-jinx]

Did you also check the front bulbs and connections?
_________________
https://www.thesamba.com/vw/forum/viewtopic.php?t=620186
https://www.thesamba.com/vw/forum/viewtopic.php?t=668799
1974 Bay Westfalia. she likes to be called Ethel.
1968 Dune Buggy
1974 parts bus
A smart man learns from his mistakes,a very smart man learns from other's mistakes.