Headlight cross-wired... I think...

jwebster · Post by **jwebster** » 12 Sep 2011, 09:54

I have a 2000 S70 glt/se turbo. I have an issue that the light bulb failure light turns on both when I turn my headlights on like normal when it's night out. But also when I use my right turn signal, but not the left. A few days ago I wanted to see what it looked like, so I turned on my right turn signal and stood in front of the car and noticed that while the turn signal is flashing so is my right headlight with it.

I purchased this car a month ago used from some shady character off of cl. It was so cheap I didn't care. Happy with the purchase and I've fixed just about everything but this one issue. When I bought it I had to replace a tail light because the light bulb failure light was on when I triggered the right turn signal only. That fixed the failure indicator on the dash but a few weeks later this started happening. I thought it might be the hazard switch because I know that they are connected there but when I put in a spare switch it still did this. If anyone has any experience with this please help. Thanks! I'll post when I get this figured out. Hoping to not have to spend any more $ at the over-priced lazy investigating dealership.

Post by **Juan62** » 12 Sep 2011, 15:53

I think you are correct. Check the wires and wiggle them slightly, then turn on lights/turn signals. I know my 98 S70 had a recall and it has some adapters to the lights...keep from burning up. Check on that too.

Post by **BEJinFbk** » 12 Sep 2011, 16:13

I have a funny feeling that the right headlight and turn signal share a ground.
And if they do, that ground is probably loose, corroded or otherwise bad.

jwebster · Post by **jwebster** » 12 Sep 2011, 18:40

"I have a funny feeling that the right headlight and turn signal share a ground.
And if they do, that ground is probably loose, corroded or otherwise bad."

I am new to electrical work on cars. But as far as I can tell bro, the connectors are wired straight back to the hazard switch. I've tested on 3 different switches too. It's not a huge concern though. I would like to say that it's fixed but it all works and is legal so I can leave well enough alone. If anyone has any ideas though I'd appreciate it.

jwebster · Post by **jwebster** » 13 Sep 2011, 08:00

Post by **BEJinFbk** » 13 Sep 2011, 10:01

The 12 volts may come from somewhere else,
but the GROUND for each of those lamps is right
there in the front right. Honest...Check'em.

jwebster · Post by **jwebster** » 13 Sep 2011, 10:13

I've done all kinds of repairs to cars, but when it comes to electrical I'm a newb. How can I check the ground that they would share. When you speak of ground you're talking either a wire or the component actually touching the frame from what I do know about car electrics. I'm not sure how they share a ground. Disconnecting the light (still plugged into it's socket) from the turn signal lamp assembly and hold it in my hand, not touching anything, it still blinks. With the only access that electricity has to the bulb comes from the wires only. Which trace all the way back to behind the glove box and under the floor. If I'm missing something obvious, please let me know. Not trying to argue, I just have taken my logic as far as it goes and I don't get how they could share a ground.

Post by **BEJinFbk** » 13 Sep 2011, 13:15

One of those wires for each lamp is the ground wire.
What's kinda wierd is the drivers side grounds are under the hood, at
ground point 31/52, but the passenger side runs all the way back to the drivers
side power distribution area inside the dash above the pedals at 31/52...Funky.
I'll have to dig deeper later.

Post by **jimmy57** » 13 Sep 2011, 13:27

The turn signals are not on the bulb failure detection system but the right front marker lamp is. If you turn on turn signal and it does not have good ground, the filament connection for ground side is in base of bulb and joined with the ground side of marker bulb and the marker bulb fillament becomes part of that circuit. The current feeds back into the circuit for taillamps and the other front marker lamp and the bulb failure module is triggered and the lamp in cluster goes on.
Ever been in traffic and a car ahead puts on brakes and the turn signal comes on dimly? Or the tail lights are on and when they hit the brakes the brake light comes on one side but on the other side the taillight goes out and no brake light lights up? all these are ground faults.
It could be the ground contacts fro bulb in the RF lamp are corroded or even a bad bulb with internal fault but good filaments.

jwebster · Post by **jwebster** » 13 Sep 2011, 13:42

That's alot of help. So the failure light comes on also when I just have my headlights on, like you would normally have on to see at night. I feel like I'm on the verge of understanding how to find the problem but I would someone to make it plain for me what to check to see if a bad ground. The wiring or some contact point on the lamp assembly? And which lamp assembly or bulb would make sense to be a suspect with the symptoms I'm experiencing. I get the flow of logic that you presented but like I said I'm new to this stuff so you really can't dumb it down too much for me.