need help! 87 cabriolet lighting problem

i have an 87 cabriolet that just recently started having lighting problems... You can only have the running lights or the headlights on... not both at the same time. I thought this might be a problem with the switch, but i "switched" them out and it made no change. the running lights came on very breifly while i had the car running, but almost immediatley went off... I really need to get this fixed... my boyfriend uses this car to drive back and forth from work and he works the night shift. Help Please!!! the interior lights also do not work.

Reply to
VWGirl
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They are two different light systems. Find the ground for the running lights which will be the problem. The interior light ground might also be located where the running lights ground problem is. If the fuses are good and you checked the switches with a multi-meter, then it's a common ground somewhere.

Reply to
Peter Parker

I've looked through the bentley manual, and it [no surprise] doesn't mention anything like this. I have somewhat of an idea as to what is causing it, but I have no reason to support this idea... so please, someone that is familiar with this help me out!!!!

Reply to
VWGirl

I don't think the interior lights work at all... ever... If this is a problem with the ground then how do the running lights work at all? I will go check the ground... but i figured that it would have something to do with the switch or drain or something, since the whole system works... just not together...

Reply to
VWGirl

That is the key. It means you have to find the common ground to the circuit which only works for the the headlights and not for the running lights. A wire is open somewhere that is not completing the circuit with the light switch on the headlight position.

Reply to
Peter Parker

Circuits failing is not like a component. Troubleshooting an electrical circuit takes practice and cannot be told what is wrong, only how to find the problem. You have to trace back from the bulb and find where its not getting voltage. Continuity tests are also useful but do not use them with the power switch on the on position.

Reply to
Peter Parker

ok... and isn't the only thing that would not be completeing the circuit the switch???????

I flip the switch to the running light position and the running lights work... i flipr the switch to the headlight position and the headlights AND the running lights are supposed to work, but only the headlights work... so the running lights circuit is complete... it's the headlight circuit that is not complete? correct???

Anyone have a diagram of the headlight switch???

Reply to
VWGirl

Reply to
VWGirl

sorry... hit the wrong button....

Well, I had this theory about the battery voltage not being high enough to support the headlights and dash/running lights, since the alternator is on the way out, but turns out this was not the case!

I went out to the car again and jumped it from it's twin, so I had 14V... this made no change... I shut them both down and began playing with the switch again, which was my initial thought as to what was wrong with the system. well, I figured out that If I put the headlights on and then slightly pushed the switch back to the running lights position, they would both work! I did this without fail probably a dozen times... so I was satisfied that it was a problem with the second switch... I happened to have a third switch available... so I popped it in... voila!!!!! It all works as it's supposed to now!!!

Maybe I should just stick to using new parts and go with my initial insticts... although used parts that i already have from parts cars seem like the cheaper way to go for diagnostics, I guess I need to have tested them as known good parts! This would have saved me a day of frustration!!!

Is this a normal problem with these switches???? Like the hazard/blinker problem? something that you just have to live with???

Reply to
VWGirl

Reply to
Randolph

sorry i hit the wrong button the first time... I posted the solution just after it... you should be able to see it :-D

Reply to
VWGirl

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