I need some help my 2002 Chevy blazer gauges wont work right and my dome lights wont shut off. My truck wont start it acts like it wants to start but dies right down after, I got it to start a while back then I bought a new computer and did the key relearn thinking that’s what it was and it started for a while but the temperature gauge and the gas gauge are still not working. I went to get the alternator tested it it’s still good Then just today i went to go start it and it won’t start and those two gauges are not turning on at all every other gauge in the truck works except those two

 

When describing your problem it would be better if you use:

1. Wont crank (starter does not turn)
2. Cranks but wont run
3. Runs but then dies

Next up is voltage. You have to start with a properly charged and healthy battery or we will be chasing ghosts. A fully charged battery is 12.6v and by 12.0v you are already more than 50% discharged. The reason why you need to measure the voltage under a load like the starter is because a failing battery (sulfated plates or a shorted cell(s) might charge to 126v with no load but crash quickly when loaded. Please state what your battery voltage is before you try starting and what it is during a failed starting attempt. For reference:



George

 

I just bought a brand new battery for it from auto zone and it’s still doing the same things

 

A new battery is good but we still need those voltages. You might have say a parasitic draw from an alternator diode, bad module or persistent light that keeps draining even a good battery. I will be glad to help you get your truck fixed but we need a process to find your problem.


George

 

The dome lights stuck on and the gas gauge and temperature gauge won’t work I think it might be a bad ground wire

 

I read your whole post carefully and the starting problem is where we should begin for multiple reasons. It may help us chase down power or ground problems and a truck can still run with a bulb pulled out and a wonky gauge panel. I asked for the definitions on no start because if it always cranks strong but wont run or runs poorly then we may be on to system powers, grounds, wires, ignition switch, relays, etc. If it wont crank then that's a different set of issues. Another reason for my starting point is that chasing ECM's, grounds, wiring defects, relays and so on is next level and we need to establish a testing process and language because its hard to fix a truck a thousand miles away over the internet, especially with electrical problems

ECM's and grounds are a common first guess and are rarely the problem.


George

 

I replaced the ecm and I just got under it and started looking for ground wires that were fried or bad and I moved a lot of them around and now it’s starting but I my gauges are still not working right so I think a ground wire is bad and my dome light is even brighter cuz the back one shut off so I pulled the fuse that way it’s not one anymore but it’s still going to pull power

 

If you don't care for my approach, no problem its your truck. I'll be glad to cut the thread loose so that you can give someone else a try.

If you want to skip diagnosis and use the parts cannon, then replace the ignition switch.


George

 

There is nothing wrong with inspecting the wiring harness but you are not just looking for bad grounds. You need to look for damaged or corroded wires: frays, cuts, green or white powder. This would be the more likely problem.

George

 

I'll cut this thread loose so that someone else can help you. I'll leave you with all your ground circuits and locations.

George