GMC Troubleshooting Questions? Ask a Mechanic for Answers
Good evening! My name is ***** ***** I will assist you
Is there any indication of a clicking or thud or any noise at all when you turn the key on?
As you hold it in the "start" position, do all of the lights on the dash go out and the dinging noise stop?
Do you have any electrical equipment like a test light that you can use to test the starter with my help?
Awesome, if you are able to get to the starter, there is a pretty simple test that you can run to see if it is getting its signal. Do you have a way to get to the starter and either an assistant to turn the key while you are down there or a long enough test lead to attach on the starter while you have the meter inside with you and you turn the key?
ok, that makes it a bit more difficult... there is a more "shade-tree" way to see if the starter is the problem. If you have a hammer, you can hit the case of the starter with medium force several times and try again...
If it starts after this, then you have a bad starter whose internal magnets are sticking to the case. If it does not start you will need to try to get a helper to run through some tests to either prove that the starter is bad or to rule it out and move on to the rest of the testing that would be required to find the problem.
Ok, that is the test that I was referring to. If he checked and there was no signal to the starter on the small wire, then it is very likely that you have a security problem or possibly an ignition switch or fuse problem. Have you checked fuses yet?
I will check to find out what fuses control that circuitry
Ok, buddy, I have a few for you, are you ready to check some fuses and swap some relays?
I have attached the diagram for the starting system. It includes the starter relay and the starter fuse.
**check fuse number 60 (40 amp) in the under-hood fuse block
**replace the relay labeled starter with anothe relay of the exact same type, perhaps the horn if it matches
Let me know how it goes and if you have any questions! Please remember to leave me a positive rating!
You are looking in the underhood fuse box, right? And making sure I have the right vehicle: 2008 GMC Sierra HD 6.6L diesel
Is there any way that you can send me your VIN number?
Has your radio clock reset?
The vin number is ***** two places that you should be able to see easily: 1) at the edge of the dash all the way at the windshield at the bottom on the driver's side corner and 2) on a sticker on the door jamb for the driver's door
You should check the following when you are ready:
1) remove both battery terminals on both batteries and make sure that they are clean and tight
2) is the security light on?
--> an easy reset procedure for a security problem involves turning the key in the "on" position for 10 minutes straight and then trying to start the truck
3) There should be two large gauge wires going to your starter from the battery (I think the battery on the driver's side) and they both need to have power at the battery and the starter. There is a fusible link in the middle of one of the wires, and they are prone to burn out.
Let me know when you have done the other things I mentioned
I am so sorry, I didn't see where you had responded...I think that my system must have frozen on your last reply asking to do it the next day.
Yes, it could be the key switch. If you are not getting any power to the signal wire on the starter, you should begin to trace it up from there. The next easiest place to check would be the starter relay. You want to see if when you turn the key to the "start" position, you are getting power. If not, you would then begin making your way up to the switch.