View Full Version : Advice needed - 05 sts headlight issues (only driver side working)

07-20-11, 10:25 PM
Hi, my sister just bought a 2005 sts. She didn't realize it but none of the passenger side headlights plus the fog light are working. I was reading that the front clip had to be removed to replace the bulbs which makes diagnosing the problem a hassle. Has anyone heard of this happening, or is there a plug or fuses that can be checked? I just find it odd that they would all go out... But seems how the car was purchased like this I have no idea if it happened one at a time, or all at the same once. Any information on this would be a great help.


07-20-11, 10:38 PM
**also the turn signal is the only light that works on that front side of the car**

07-20-11, 10:53 PM
Many states require all sellers of used cars to disclose safety issues. Headlights would qualify. Here in Wisconsin, if such defects were not disclosed, the seller is obligated to repair them (i.e. consumer protection laws apply to private sellers, too.)

Was it purchased from a 'dealer'? Many 'private sellers' are actually 'dealers' under state law. (In Illinois anyone selling more than a certain number of cars a year automatically qualifies as a dealer. I can't recall how many cars that is!)

In any case, it doesn't hurt to try!

07-20-11, 11:23 PM
Thanks for the reply. She purchased the car from a private party seller. The people were really nice, and after re-reading the post on auto trader they had said something about the lights. They knocked 1,000 off there original asking price being they knew it had a few small things wrong. She did not tell me about the headlights being out till about a week after she had bought it. Now I'm trying to diagnose the problem. I would prefer not taking it to a dealer being a am rather good at fixing things myself. I typically fix everything on my caddy's and vette, but sometimes I like to figure out known issues being killing myself trying to find a problem that somebody else may have delt with. (like are all three of those lights on a relay, ground, or bodycontrol module)

07-21-11, 12:23 AM
So I haven't been able to determine for certain from your posts, have you checked the fuses? This should always be a starting point in the absence of a simple defective bulb. Also, what kind of headlamps does she have, halogen or HID (all high beams are halogen, my question relates to low beams)?

Some people are a little neglectful of their car. Being that this was a recent purchase, you may want to consider things such as multiple burned out bulbs (more likely with halogen than HID). I've seen several instances where someone says all their tail lights don't work and the tech jumped on the brake switch or relay, later to discover the owner never checked their lamps and replaced them as they failed and now they're all out.

I always go with simple first, complicated later.

BTW, the left and right headlamps and high and low beams do have separate fuses (4 fuses in total). To help rule things out, if one side works and the other doesn't, it won't be a relay. The high and low beam relays are shared between the left and right side of the car. Similarly, since this is the case it also won't be the Instrument Panel Module (IPM). This module controls the headlamp relays. You need to look somewhere after the fuse block. It's either a problem within the headlamp assembly (may be a bad bulb, bulbs or something else) or wiring between the headlamp assembly and the fuse block (considering it may also be a grounding issue from the headlamp assembly to the body).

07-21-11, 12:42 AM
Looking a little closer, all the headlights along with the fog lights share the same physical ground point on the body (G104). This tells me the ground point won't be the problem or the left lamps would not work either. It could still be a ground problem, but it would be with wiring and not the connection to the body.

07-21-11, 01:39 AM
Ok thanks for the information! I believe it does have HID's, I'll know more when I actually get to mess with the car. She has only sent me pictures and they look like hid's, but it's hard to tell. I'm going to guess bulbs, but I'll check the fuses first. That should get me a good start on things at least.

07-21-11, 04:55 PM
Have her snap a pic of the RPO sticker affixed to the lift-up cover over the spare tire and send to you. The code TT6 would indicate HID equipped car.


07-21-11, 07:43 PM
If it has OEM HID's, you'll see a little pop-out door for each of the 2 headlight washers.

If upgraded to HID using aftermarket parts, the plot thickens!

07-22-11, 09:19 PM
Ok I had her send me the RPO number, it does not have hid's. She took it into the shop and they said the wires are melted on that side. Meaning the wires for the fog light and high/low beam. Does anyone have a diagram? Also they said the wires inside the headlight are messed up? I'm kind of curious how they knew this unless they tore the front clip off. Would anyone have a part number for the melted wire (passenger side?)

07-22-11, 11:32 PM
Actually TT6, TT7 and TT8 are all HID systems so you may want to check this. If I'm not mistaken (and I do have a little more research to do), these are different flavours based on LHD or RHD and whether the high beam dimming option is installed.

I would recommend that you may want to make a small investment and you'll have access to the actual GM service information for this and all other GM vehicles. $20 US will purchase 3 days of access to the same service information GM technicians have (schematics, description and operation, connector information, wire colour, gauge, etc).


To register is free and then you can gain access to the subscription areas.

07-30-11, 10:26 PM
Ok, I took of the front bumper cover and found that it was the wireing inside the headlight capsule (the connector to the low beam bulb had melted.) This was a lot simpler then I had anticipated. It took me about 1.5 hours to tear it apart check things out and re-assemble. I ordered a broken headlight off eBay (for 43$ shipped) that the wireing was still in good condition. This should fix the issue. So thanks for everyone's input, it is much appreciated!