Think I fried my pcm?
Think I fried my pcm? I'm wrapping up a 2004 ls1 conversion. Got every thing installed and wired up. My fuel pump was not coming on by the computor so I jumped ground to the relay contol wire. Started up right away, let it run for about fifteen seconds and turn the key off. the engine kept running. so I unhooked my fuel pump ground. After knowing the engine would start I finished up a few small things; extending my 02 sensors for headers and trouble shoot why pcm was not turning on fuel pump. Turns out the pcm send voltage not ground to relay,(so I was shorting it out dohh) rewire relay, now pcm controls fuel pump but engine will not start. Not getting spark or injector pulse, I can see rpm on scanner though. Removed and inspected crank sensor looks fine. Fuses for injectors and coils still good.Guess my question is:
1. can you fry that part of the computor thogh that circut and the fuel pump control still work?
1. Any other things to check or try would be appriciated.
1. can you fry that part of the computor thogh that circut and the fuel pump control still work?
1. Any other things to check or try would be appriciated.
Switched the crank sensor with my trucks. Truck runs and car still does not. Guess I'll order a ecm off e-bay. "Spare ecms" programs it with your vin number, hopefully I won't have to use any additional hp tuner credits. Any one know about that?
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I just bought an s-10 ecm off them and it worked smoothly. As for hp tuners and the same vin. IDK
You will have to re-license it to the new PCM. The vin doesn't matter, even with HPT.
Sounds more like you may have a ground not hooked up some where if your still seeing RPM on the scanner and the fuel pump is still working.
FWIW, I did the same thing with the fuel pump relay with the 72 Chevy 4x4 I put a 5.3 in for my dad. Switched over so the PCM powered the relay and it was fine...
Sounds more like you may have a ground not hooked up some where if your still seeing RPM on the scanner and the fuel pump is still working.
FWIW, I did the same thing with the fuel pump relay with the 72 Chevy 4x4 I put a 5.3 in for my dad. Switched over so the PCM powered the relay and it was fine...
Last edited by kbracing96; Jan 28, 2010 at 12:04 PM.
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that would have not shorted out your computer... if you were thinking the pcm put out ground then you would have hooked up the other side of the relay to 12v source, in turn you were wrong all it did is run 12v+ to 12v+ (it also had a resistor in between) so you switched to 12v pcm to relay resistor to ground.... this shouldnt have caused in issues i would check your relays and power and ground sources....
i hoooked mine up the same way the first time.
i hoooked mine up the same way the first time.
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Verdad Gallardo that would have not shorted out your computer... if you were thinking the pcm put out ground then you would have hooked up the other side of the relay to 12v source, in turn you were wrong all it did is run 12v+ to 12v+ (it also had a resistor in between) so you switched to 12v pcm to relay resistor to ground.... this shouldnt have caused in issues i would check your relays and power and ground sources....
i hoooked mine up the same way the first time.
i hoooked mine up the same way the first time.
So today is the fourth round between me and this problem (still have my eyes)though mostly short matches as every thing I check is good and I soon run out of ideas. Thew a $120 non refundable part at it. (anybody need a spare computor for cheap?) I backed up and started going from the basics checking every wire at the computor for the second time. Thought to check if the key on voltage is powered up during start too. Bingo. Rewired now it starts every time. Great day, celibrated by going sleding with the kid( once a year thing at best around here).Feel really dumb at the same time, getting rpm on the scanner plus starting once (must have timed it when the key turned back the motor was still spinning?) really threw me off. Any way thanks for the responses.
