willscotmont

I have an 05 C6 with 86,000 miles on it. (My daily driver) The headlights are set to "auto" and work properly when the car is cold then after about 15 minutes the lo-beams go out. High beams and fog light function still works properly. The dash indicator on dash indicates lights are on even when they are not. When its night time and you turn off the lights manually the dash displays "HEADLIGHTS SUGGESTED". Using the multifunction turn signal switch to turn on the headlights manually does not turn on the headlights. The night time sensor appears to be working properly. It appears to be a thermal problem. You can drive a short distance and the headlights work properly. Park the car and drive it a short time later and the headlights don't work.
I've replace the relay in the fuse box, cleaned the four ground connections in the engine compartment, and split the fuse box apart and spray cleaned all the connections. It still has the problem.
Anyone with similar probems or can suggest a path to follow?

torquetube

Yes, it is a thermal problem. The low-beam circuit within the backplane of the fusebox itself has failed and is opening up when hot. I describe it in more detail here:

http://forums.corvetteforum.com/c6-c...post1577560168

You could jumper around it, but the cleanest solution is to replace the fusebox itself. It does cost a fortune, but the new ones come fully-populated with fuses and relays so at least you get some spares.

Do please report your problem to the NHTSA as this is a real safety issue that should result in a recall. It seems to be a failure peculiar to that circuit inside the 'box, or else we should see other circuits failing at random, too.

It's especially attention-getting when the lights suddenly conk out while driving at night.

Here's the report form: https://www-odi.nhtsa.dot.gov/ivoq/

willscotmont

Thanks so much for your post. It's apparent that this is a fairly common problem. When I had the box apart I thought the spade connectors underneath went straight through the plastic to the fuses & breakers. I didn't see how there could be any thermal malfunction. I did not detect the "backplane" you refered to in your post. After dismantling the box and reassembling it I feel like I would have no problem replacing it. If there are any pitfalls to replacing it myself I would appreciate any suggestions you would have to offer.

Thanks again.

Scott

RLSebring

Just make sure you get the correct box for your year. I see them here and on eBay for around 175.00 of course used may be buying the same problem...

torquetube

Yeah, at first glance it looks like the connectors go straight through but in fact it's two punchdown blocks with a stack of wire-routing grids in between. As you discovered, the box itself is easy to remove and replace.

If I recall correctly, you can loosen the long screws that secure the big harness connectors and then push on them to pop the connectors out. This beats rocking on the connectors themselves.

Also, I'd disconnect the negative battery terminal first so you don't risk shorting the power connector on the side of the fusebox.

willscotmont

That tells me I need to take a closer look at parts when I get them apart. Good tip about the long screws. I remember being concerned about pulling those large connectors off squarely to avoid damaging the individual connections. Later I was reading the service manual where they describe and picture using special pliers just to remove the relays from the box for the same concerns. The ground cable is a given anytime I mess with something electrical.

Just when I though that I was getting close to finding the solution to this headlight problem someone else has proposed another possible cause. I called a well known Chevy parts man in my area that I had used twenty-some years ago when I restored a 1972 Chevy Longhorn. He was knowledgeable and helpfull back then so I saved his card and gave him a call yesterday. To my surprise he was still there. He did some inquiring around the dealership and couldn't find any techs that had run into the fuse box problem. He corroberated checking the ground connections but suggested it could be the regulator inside the alternator. If the voltage drops too low the head light ballasts would not have enough power to function. I'm still leaning toward the fuse box but I want to check this out today before I spend $460 replacing the box. I'm going to drive the car today with the headlights turned on manually until they fail. He states I should be able to detect a voltage drop with the dash information readout. He tells me if the reading gets down around 11 volts the alternator is a probable cause. I'm giving this idea some extra creedence because a couple of weeks back I did notice the rear view mirror dome lights pulsing slightly at idle.

I did file a complaint with the NHTSA. I also called the Chevrolet Customer Satisfaction line in Detroit. The woman appeared concerned and was going to investigate contacting the dealership first. She called me back at the end of the day and said she hadn't been able to reach the parties at the dealership. She promised to call me back today.
I acknowledged that this car is out of warrenty but my complaint is that this fusebox has no moving parts and no electrical components that should wear out or be effected by time. She asked me what GM could do for me and I responded that they should recall the fuse box and replace it for free. It obviously has a design flaw. She replied that she would investigate it.
We shall see.

Thanks again for your input. I will update this post as I discover more.

FireRoc

I do not think that is an indicator of a bad alternator. I have a 2005 C6 and have noticed that all the interior illumination lights and parking lights do the same thing when the car is idling.

BTW, my alternator was replaced at about 57,000 kms (40,000 miles) as it got very nosiy when under a high load for a period of time.

willscotmont

I wasn't too concerned about the alternator when I saw the pulsing dome lights. The battery seems to be charging while driving with no starting issues. At the time I did take it up to O'reilly Auto Parts where they will put it on their test machine for free. I know sometimes an alternator can indicate charging but because diodes may be going out it can be outputting AC current instead of DC which will damage other electrical componants.

Yesterday I drove the car until the headlights failed again and the voltage reading in the dash remained normal; about 13.8 volts.

willscotmont

I wanted to let you know the final outcome of my headlight problem.
I called the Chevrolet Customer Satisfaction line in Detroit. My complaint to them was 1) the technician stated that he "thinks" the headlight problem was caused by the fuse box. 2) The fuse box is not a wear item. Except for the relays & fuses it should not fail. It clearly has a design problem. They asked me to return to the dealer where they did verify that it was the fuse box. The Detroit people escalated the situation to their district manager. After a few back & forth calls with the dealer and Detroit they agreed to warranty the part and I had to pay labor chargers of $194,
Thank you for your input. It was very helpful.
Scott