ls1 swap nightmare pcm wont comunicate with tac

**Ron s** · 06-16-2010, 03:36 PM

I am haveing lots of proablums with my ls1 swap. what i have is a 1967 camaro that i fitted with a 2004 silverado 6.0 2500 motor i got the wiring harness frome ebay and pinouts off line the pcm wont comunicate with anything. the pcm was programed with the vats removed rear o2 sensers deleated by spare ecm i sent back the first pcm and i was told that the pcm had a major short i checked the pinouts against three diffent websites pinouts witch were all the same i cant figure out why it keeps shorting out i allso realised that the motor is grounded to the motor the pcm is grounded to the motor but the body,s not grounded to the motor it is grounding through the transmission lines the pcm is in direct contact with the body would this cause a short o and by the way none of the fuses ever blew can anyone help me thanks

**Z28Thunder** · 06-16-2010, 06:13 PM

Welcome to LS1.com!!!!

You might want to post this question in other sections. I would try the top one which is computer and tunning. I think there are 2 tach sensors on the f-body. The rpm's are calculated by the pcm via crank sensor input and sent to the IPC through a serial data cicuit. Could be a crank sensor or internal pcm issue. And if ircc there is a cam sensor under the intake as well.

http://www.ls1.com/forums/forumdisplay.php?f=9

http://www.ls1.com/forums/forumdisplay.php?f=6

http://www.ls1.com/forums/forumdisplay.php?f=70

**pajeff02** · 06-16-2010, 06:38 PM

Welcome to the site! Not sure what is going on there... hopefully someone here can lead you in the right direction.

**Ron s** · 06-17-2010, 02:50 PM

ok i got it to spark thare was a brake in one of the power wires to the pcm. but my throttle by wire isnt working it just pulses at key on and wont work wen i press the gas pedal ime going to check for codes tomorow hopeing its just the pedal its self any advice would be grate thanks.

**Ron s** · 07-15-2010, 05:13 PM

so any one have any ideas why my pcm wont actuate my fuel pump

**Cutlass** · 07-15-2010, 07:25 PM

are you using an 04 silverado computer and harness or something else??

**Ron s** · 07-16-2010, 04:53 AM

its a re programed pcm from spare ecm its programed with a 04 silverado software. the harness is from a 04 as well. the pcm sends a week signal briefly and nothing during cranking. and vats was removed

**Frost** · 07-16-2010, 11:51 AM

The fuel pump doesn't run during cranking... It runs for a short prime-time at key on and then it comes back on when the vehicle starts. If you have a system that leaks down when the pump isn't running, you need to set the pump up to run it's relay at key-on rather than the PCM.