Hello all. My son bought a 2000 Chevy Blazer LT a few days ago and we have ran into a BIG problem. When he bought the Blazer it was running and moving. Noticed some things wrong with it but to me it was a few simple fixes so no big deal. Did notice the ground cable from the negative post to the front of the engine was melted and found some of the harness too was melted but still vehicle ran. He took his Blazer to work that night and I get a call from my son saying that he was stuck not too far from his work and the Blazer is dead. Asked him a few questions and he says there is no power at all to the vehicle. So I am thinking well alternator is shot and the battery is drained no biggie we can replace that. I arrive to where he is at and I check the Blazer myself just to verify and yep everything is dead. No dash lights. No brake lights. No headlights. Everything dead. He said the battery light came on and a something with security flashed but it still didn't make any sense. Next morning took out the battery and alternator to have tested just to verify these were the culprits. Both tested and both came back good. So I had to think more what else could be wrong and why is the whole vehicle dead and have absolute ZERO power. Checked mega fuse and it looked corrosive so replaced it thinking okay I might have found the problem. Put everything back together and nope still ZERO power. Started tracing all grounds and checking all cables. Found the positive cable going to the starter and giggled it and I thought I found the issue. Checked the connections it's secure but find the starter solenoid is loose from the actual starter. In my head I am thinking this wouldn't cause the issue of the Blazer not having ZERO power to anything in the vehicle so I will admit this has stumped me and I am at a loss of what else could be wrong? Has anyone else have this experience and what else could I be missing that I am not looking at? Anything would be helpful.

 

What is the resting battery voltage with the meter leads at the battery posts?

Same question when you turn the ignition switch on

Same question when you try to crank?


George

 

As an aside. looks like the A.I.R. check valve in the exhaust manifold has been leaking and melting wires to/from the PCM. Some of these wires go to the injectors (don't ask how I know). But also looks like an attempt has been made to repair the rubber hose on the check valve?? Loose hose clamp?? Note this hose gets hard/brittle and fails when check valve doesn't check the exhaust trying to run backwards through it. New hose without fixing check valve routes unchecked exhaust through the A.I.R. switching valve and even the A.I.R. pump, typically ruining them as well. I am guessing that a P0410 code is in your future, but it will not prevent the vehicle from driving. You can pull the hose off, start the vehicle, and listen to test the check valve.

Follow George's lead in post #2 for electrical being completely dead.

 

Hello George and Les. Thank you for the reply and I apologize for my late reply. Funky work schedule. So I had the battery out of the Blazer and did the voltage test and the battery was at 12.59 volts. I put the battery back into the Blazer and reconnected the battery cables and did another voltage test and it was still at 12.59 volts. Turned the ignition to the on position and volts did not move. Did the crank test and volts did not move still at 12.59 volts.

 

Next, pull the IGN A fuse (40A) in the UHFB and with the battery connected measure the voltage at the two fuse sockets, black battery probe to battery ground.

George

 

Good morning George. So pulled that 40A fuse and tested out the socket. The socket on the engine side tested at 12.51 volts and the socket towards the front frender side tested at 0.00 volts.

 

OK so we have a properly charged battery and the 175A maxifuse is OK, at least with no load. Next remove the ECM1 fuse (15A), turn the ley to run (key on) and test the voltage in both fuse pin sockets. Then turn the key to start and do the same for the crank fuse (10A).

George

 

Good afternoon George. I removed the ECM1 fuse and tested the sockets with the key in the on position. Front socket tested at 12.43 volts. Back socket tested at 12.36 volts. Tested the 10A crank fuse next. Front socket tested at 12.37 volts. Back socket tested at 12.43 volts

 

So then your ignition switch is at least partially functional. Next check for clean dry connections for all three battery negative terminal attachments to the truck. Then pull the starter relay. One pin should have always on 12v. A second pin should have 12v only during a start attempt. Is this the case? Also, make note of the pins.


George

 

Good morning George. So I don't know how to explain this but yesterday while I was at work I get a call saying the headlights were on and hazard lights were flashing on the Blazer. I did not get a chance to do those steps that you had asked and nobody has been in the vehicle so I don't know what to say but I am not going to take any chances driving it. I had asked my son to go out and see if there is still power to the Blazer and try to start it so I am waiting for his response. I want to continue trying to find out what's wrong but I am afraid to move it. Have any thoughts on what I should do?