light problems with my 1998 pontiac transport

[kitefliero]

Can anyone help me? I have a major problem with the turn lights and parking/tail lights on this van. when the ignition switch is on and the running loghts are lit in the daylight everything works normal. the minute night fall comes and the headlights come on, or if you turn them on manually it seems to backfeed through the parking lights and the turn on one side will not flash. when this happens the turn indicator lights both come on dim. I have tried checking to see if all bulbs are grounded and they seem to be, but when i check the parking and tail lights the have back feed. thanks bob

[Headnsouth]

Check to see if you have some bulbs out.

[ogauge4me]

kitefliero
Which side seems to be the problem, passenger or driver?

When you operate the turn signal does the back up light come on as well?

Do the lights flash dimmer, when looking from the outside, than normal?

When the turn signal is activated do both turn signal indicators flash?

When depressing the brake does the dash turn signal indicators light up as well?

[kitefliero]

oguage4me and headensouth:
Thanks for your input. Yes the first thing I checked was that all the bulbs would burn and then started checking system to the best of my ability. I got a schematic of from the internet and I really have trouble understanding that. I thouhgt it might be the daytime running module, but could not locate it.
Now to answer oguage4me. Well it started out to be left one I had the trouble with flashing. The back up lights appear to work fine, but they are on a completely different run , from what I can tell. When the turn signals are on they seem to be bright, however it back feeds through the tail lights and they flash dim. This led me to believe there was a poor ground, but after checking each and every ground they all appear to be good. The indicator lights on the dash will light dimmly when the headlights are turned on and that is when the turn will not work. with just the ignition switch on every thing seems normal other than backfeed through the tail lights and the front parking/turn lights are on bright all the time. the flash being from the flow of voltage being stopped to cause the blinking. When the brake is depressed the turn signal stops flashing. All of this is the way it was until this afternoon. I was out there trying to fix it and I evidently grounded a live wire. It didn't blow the fuse as it should have, but instead I think it probably burnt a wire in two. It smells terrible and my bottom end hurts terribly from kicking myself. How dumb was I. I know better. Anyway now everything seems to work other than no turn signals or flashers.Thanks again for your interest in helping me

[LMP]

PRoblem with water intrusion in the rear lamp clusters is a well known and common problem with this van. A lot of corrosion develops in the printed circuits inside the clusters . ALl sorts of weird consequences follow.
Just remove the clusters and inspect.

[etbill52]

Originally Posted by ogauge4me

kitefliero
Which side seems to be the problem, passenger or driver?

When you operate the turn signal does the back up light come on as well?

Do the lights flash dimmer, when looking from the outside, than normal?

When the turn signal is activated do both turn signal indicators flash?

When depressing the brake does the dash turn signal indicators light up as well?

This is the same problem I had with mine, I removed the passenger side tail light, the wire that plugs into didn't look right, I cleaned it and with a small screwdriver I bent the ground contact over to make it tighter. That fixed the problem.

[ogauge4me]

Originally Posted by etbill52

This is the same problem I had with mine, I removed the passenger side tail light, the wire that plugs into didn't look right, I cleaned it and with a small screwdriver I bent the ground contact over to make it tighter. That fixed the problem.

I used a small file to remove the black oxidation from the main ground pin. The reason the lights are acting weird is the battery is trying to find a ground any way it can including back through the lamps in the dash.

So far I have not had any further problems but I am sure the overall reason is that there is not enough copper wire for the main ground. I expect the problem to reappear in the future. At least I will not have to spend 3 hours hunting the problem down.