98 v70 turn/brake light problem. MVSOLVED. Bad ground wire

Post by **98v70dad** » 22 Jul 2013, 10:06

When I put on a left turn signal on my 98 v70 the lights blink but the bulb failure indicator comes on and the bulb failure indicator blinks also. When i looked from the back of the car the turn signal is coming on at about 25% strength and one of the brake lights on the right side is coming on at 10% even though the brakes aren't on. I am going to the used parts store to buy a used tail light controller to eliminate that as a possibility. I've recently replaced the blinker relay and its working fine so its not that. Any other ideas of what it might be? If you think its a short where are typical places to look? this is the latest in an ongoing two year problem that has gotten worse and worse. It started with the tail lights not working even though the bulbs weren't burned out. Removing the bulbs and reinstalling them always fixed it in the past.

Post by **rspi** » 22 Jul 2013, 11:00

Bad head light switch.

Post by **98v70dad** » 22 Jul 2013, 13:08

The guy at the used parts store talked me out of the tail light controller and INSISTED that the problem is a poor ground on the drivers side. I asked for help so i'm not disagreeing with you but how does the head light switch have anything to do with brake lights and rear turning signals? In the meantime I'll take a look at the wiring diagram.

Post by **98v70dad** » 22 Jul 2013, 18:39

There never seems to be much interest in electrical problems. This has been plaguing me for over two years and I really could use the help if anyone has some ideas. Almost all the problems I've had with this car have been electrical and this is the only one I can't solve. Its now gotten bad enough to be a safety issue. I would really appreciate any ideas. One person suggested a new headlight switch and I'm going to check that out. The only other suggestion i've gotten that I haven't used yet is to add an extra ground wire for the tail lights on each side. bad ground has kept coming back as a suggestion from many unrelated sources. Can anyone tell me where the ground wires for the tail lights are screwed into the frame?

Post by **BEJinFbk** » 22 Jul 2013, 21:55

I agree that the headlight switch is not involved.
I also agree that the Bulb Failure Warning sensor
is not the problem, since only the brake light
runs through it, not the turn indicator.

I'm going with a bad ground, too.

Check the black wires at the connectors in the
D- pillar behind the lamps. and you can follow
those leads back to the body ground points and
snug them down, while you're in there.

Has this car ever been flooded?

Post by **98v70dad** » 23 Jul 2013, 00:30

I've suspected the ground for a long time but haven't checked it because we live in the southeast and cars just don't get corrosion on them unless they've been flooded. I bought the car from a neighbor and I don't think it was ever in any water. I can't think of any reason why the ground would be bad but if it is it is. The car is a wagon so if the ground point is near the floor area something could have been spilled.. The guy at the used parts place told me that he thought the ground point is up on the d pillar on one of the fasteners that holds on the tail light assembly. If the tail light was ever replaced the ground connection could have somehow gotten left off or isolated so its not making contact. if anyone knows where the attach point is for the ground it will save me a bunch of work. I checked the wiring diagram and the turn signal circuit does not run thru the controller as so that's ruled out.

Post by **BEJinFbk** » 23 Jul 2013, 00:55

The more I think about this, the weirder it seems...
Each side has it's own ground. And only ONE brake light?
Are you sure that you've got all the correct bulbs?
Any strange trailer light wiring going on?

Post by **Ben850** » 23 Jul 2013, 04:40

I've noticed my tail lights will act up if I don't replace both sides at the same time, with the exact same bulb.
I've heard similar stories of the sensitive nature of the lighting circuitry.

Post by **98v70dad** » 23 Jul 2013, 08:53

Before I went to work this morning I found the ground wire on the left side D pillar and wiggled it around a bit. The attach point to the chassis is on the D pillar a little below all the lights. It doesan't look the least bit corroded and the wire doesn't seem to have any breaks in it. BUT wiggling it made the fault go away ... everything works as it should for today at least. Many of the wires in this car seem to be too short and they don't have any strain relief. I'm not 100% convinced I've found my problem but I think its somewhere in that ground wire. It will be a pain to fix because its in a giant bundle of wires wrapped tightly in electrical tape. 15 years of Southeastern Summer heat has turned the tape into a gooey mess. I'm thinking of adding a jumper to ground for each of the lights using that ground point (E8 on my wiring digram in the Haynes Manual) instead of repairing the break in the existing wire. Does anyone have any thoughts on the jumper idea? I appreciate the feedback and help.

Post by **abscate** » 23 Jul 2013, 12:48

Kudos to the parts guy.

It IS a bad ground. People who trailer and are used to hooking up trailer lights see this all the time . When the ground gets "iffy" the voltage shorts to ground through the filaments of the other circuit in the bulb - you then see weak brake light or other lights coming on with the flasher.

I move small boats and actually wire dedicated grounds to the lights on the trailer to eliminate this hassle.