Hello everyone, my name is Joe and I'm just beginning some diagnosis on an 02 Blazer that is presenting some pretty strange symptoms. Hopefully some of the fine members here can help me figure this thing out.

So heres the story; its my kid brothers blazer so the issues were not witnessed first hand. A few months ago the truck stalled out right after start up, turn key wont crank, no CEL, and according to him no Security light. After an hour of intermittent turning the key it decided to start. He said it ran alittle rough but got home no prob. Behaved perfectly fine for a month plus. More recently it cut out on him again just after start up, and again after hour(s) of come and go attempts at starting it fired up and he limped it home. This time I came by and she fired right up for me, checked the idle, no CEL, Rev'd well and I took her for a short spin and she behaved well. The following day it died again and it stayed there, it started the following day then immediately died and I had it towed.

The symptoms: No CEL, No Security light, 1 code U1041 (ebcm comm problem), Does not attempt to crank, in Key on position fuel pump does not run at all. In Key on position blower controls do not function

Where I'm at so far:
-pretty sure not ignition switch, when cranked the radio and dash display turn off like its supposed to
-Albeit unlikely im working on the TSB for the EBCM, redoing ground tomorrow just in case
-PCM data stream looks correct w/ key on (I see TPS% changing with pedal) so I dont believe it to be faulty
-No SEC light on so I'm doubtful its security related

So besides the U1041 It's really not giving me alot to go on. Any insight would be greatly appreciated. =)

 

Was this no start condition after or during a lot of rain? If so, go to the 2nd Gen. Blazer section and do a search for 'No start in rain'. This is a fairly common problem but the answers are many:needs a major tune up with all AC Delco parts, ICM may be getting moister inside, CKP sensor, Do a search.

 

To the extent of my knowledge weather wasn't a factor. And during the heads off top end rebuild of the engine over the winter I did a major tune up. I am uncertain what icm stands for, but am very doubtful of the ckp being the culprit due to the no codes, no crank, no fuel pump deal. Im really trying maintain the mindset of looking into what the pump and starter have in common. So far to me its screaming control system, but I guess ill find out. Thanks for the tip and anymore assistance is welcome.

 

ign switch is VERY common, test for voltage at the starter solenoid when the key is turned. The code U1041 means the other computers lost contact with the ebcm, that should only effect ABS. The security system WILL NOT shut a car off, just make a no start condition. My thought is Ign switch

 

I will double check it as it was my original suspicion, but key on powers radio and dash. But does not prime fuel pump. Key held at cranking position cuts the radio and dash display but does not engage solenoid or starter motor. Those behaviors seem to confirm the function of the ignition switch in all positions, if you have a reason to suspect otherwise then I will start to spot check switches. I was really trying to avoid taking a close look at any one part until I can figure out something that adds up to a reasonable possibility given the symptoms and commonalities. (No blower, no crank, no fuel pump, whatever it is kills the running truck, and now has it totally crippled)


Thanks for the reply!

 

No fuses popping right?

 

All good in the fuse dept, checked those, relays and double checked batt voltage yesterday after completeing tsb for ebcm ground repair. Didn't change her behavior at all...... Dirty bitch