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FIX  IT MAN
FIX IT MAN, Master Technician
Category: GMC
Satisfied Customers: 17170
Experience:  Master Automotive Technician
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GMC Sierra 1500 HD SLE: I have an '02 GMC Sierra and the headligh

Customer Question

I have an '02 GMC Sierra and the headlights quit working. The DRLs still work, and the park lights come on with the night sensor, but NOT the headlights. I replaced the headlight switch with the same functions. Any thoughts?
Submitted: 1 year ago.
Category: GMC
Expert:  FIX IT MAN replied 1 year ago.
Hello, my name is Bobby. Thanks for the question. Can you tell me if the brights still seem to work fine?
Customer: replied 1 year ago.
No. As I said NO headlights work, bright nor dim. Only the DRLs in the day and the park lights come on with the night sensor.
Customer: replied 1 year ago.
Did you get my answer, Bobby? I have no headlights at all. Only DRLs and then marker lights only when the night sensor comes on.
Expert:  FIX IT MAN replied 1 year ago.
Sorry for the delay. I have been unavailable. Did you still want some help with this?
Customer: replied 1 year ago.
Yes.
Expert:  FIX IT MAN replied 1 year ago.
Great. Lets see what we can do. I just need to know if you have a voltage meter to run some tests just to see where to start.
Customer: replied 1 year ago.
Yes I have s digital volt/ohm meter.
Expert:  FIX IT MAN replied 1 year ago.
Thanks. In the fuse box under the hood locate the headlamp relay. Start by checking to see if you can feel it physically click when you turn the head lamps on. If not then leave the key on and remove the relay. With it removed check the voltage at each of the 4 pins and tell me what the readings are.
Customer: replied 1 year ago.
Yes it clicks.
Expert:  FIX IT MAN replied 1 year ago.
Thank you. That is a god sign to start. If you remove the relay and turn the key on do you get battery voltage at two of the 4 terminals?
Customer: replied 1 year ago.
Yep, sure do.
Expert:  FIX IT MAN replied 1 year ago.
Thank you. It sounds like you have a ground issue at the left side of the dash above the fuse panel. There is a splice pack there with several wires going to it as a ground. This ground is probably loose or failing.
Customer: replied 1 year ago.
I appreciate the answer, but without a pic or diagram I'm not quite sure where you are talking about.
Expert:  FIX IT MAN replied 1 year ago.
Let me see if I have a picture of it.
Customer: replied 1 year ago.
OK. That would help. If it is the problem.
Expert:  FIX IT MAN replied 1 year ago.
Still checking. My main database does not have them.
Customer: replied 1 year ago.
OK. Let me know if you come up with something that will help.
Customer: replied 1 year ago.
I'm being asked to rate your service. I decline to do so as my issue is far from fixed. Any questions? Dave
Expert:  FIX IT MAN replied 1 year ago.
Please do not rate. Over the last day or so my system has been down. If possible give me until tomorrow to see if I can resolve this. If I cannot I will opt out and allow someone else to help you.
Customer: replied 1 year ago.
OK. I wasn't going to rate yet.
Expert:  FIX IT MAN replied 1 year ago.
I do not have a diagram for this ground. The best I can explain it though is to remove the fuse box cover on the left dash fuse box. If you look at the box and look up and to the far right of the opening you will see the ground splice pack. I would also check the ground connections of the negative battery cable. Especially the one at the front of the frame on the passenger side.
Customer: replied 1 year ago.
OK. Well none of that seems to be the issue. I ran a direct ground to each light individually and nothing has worked. Now what?
Expert:  FIX IT MAN replied 1 year ago.
If the relay is clicking and if you have power to two terminals at the relay then you are losing power at this point between the relay and the headlamp. It may be in the bottom of the fuse box where you are losing it. I would check for power at the headlamps and then work your way back to the fuse box. Check the connectors on the frame rail under the master cylinder also.
Customer: replied 1 year ago.
At this point it sounds complicated. I'm just going to have to take it to the dealer and get it fixed by someone who knows what to do.
Expert:  FIX IT MAN replied 1 year ago.
It definitely is sounding like a fuse box issue. If you would like I can opt out and see if anyone else can help you.
Customer: replied 1 year ago.
I have power at all the fuses in the electronic center and the dash fuse box. So I'm at a loss.
Expert:  FIX IT MAN replied 1 year ago.
If you have power at all of the fuses and not at the lights themselves then you are losing it between the fuse and the light. The power leaves the relay and goes to each headlamp fuse. Once it leaves the fuse it goes through the fuse box and to the head lamp. If it is not making it to the headlamp then you have a loss of power either at the fuse box or between the two. That is why you would need to trace the wires from there.
Customer: replied 1 year ago.
From the headlights to as far in the loom as I can trace there is no power. I would physically have to separate all the wires in the loom. There hasn't been a wreck or anything.
Expert:  FIX IT MAN replied 1 year ago.
Then the loom should be fine. The issue will more than likely be at the bottom of the fuse box.
Customer: replied 1 year ago.
I'll have to check it tomorrow when there's some more light.
Expert:  FIX IT MAN replied 1 year ago.
Let me know what you find.
Customer: replied 1 year ago.
There seems to be nothing obvious at the fuse box. There wasn't power to everything but I don't know what they all go to, so .
Expert:  FIX IT MAN replied 1 year ago.
At this point you are going to need to test the wires from the fuse box to the headlamps to find the issue. It has to be in the fuse box from what you are explaining. If you want I can opt out and allow other experts to take a look and see f they have other ideas.