first did shbox opti signal test, (i am a dumbass and did it wrong), i thought the results ment coil, replaced, still no start. Did test right this time, not getting 1 - 4 volts on A/C while cranking w/ DVOM hooked up from B on ICM wires to ground. That meant Opti or wiring or PCM, replaced opti wires, no worky.
Today i replaced the Opti, still no fire, getting the same results on the DVOM test.
I don't know what else to replace other than the ICM (can't find a test for it) Crank sensor (checking it now) and the PCM....
frustrated...... (and hot)
__________________ 2008 Silverado Crew Cab 4.8 (stock) slow
1996 Formula Convertable (not broke anymore 8-4-09) (( BROKE AGAIN 8-15-09)) DEAD slow
alright, was getting 3 volt high res and 1 volt low res at the PCM from the opti, so i figured it had to be the ECM, put a buddy's ECM in and still same results, i know that some kind of signal is getting to the pcm but maybe its not the right signal???
Today we are going to check for perfect continuety from the opti plug all the way to the ECM, if all that is good i am going to take apart the brand new opti and look for failure...
__________________ 2008 Silverado Crew Cab 4.8 (stock) slow
1996 Formula Convertable (not broke anymore 8-4-09) (( BROKE AGAIN 8-15-09)) DEAD slow
AFAIK, the opti sends a signal to the PCM which in turn sends a signal to the ICM which then triggers the coil to fire. If your PCM is getting the right signals (only way to test that properly is with an oscilloscope) and your PCM is not bad, then it could be a faulty ICM not causing your coil to fire.
__________________ I am kind of a big deal...people know me.
Dishing out reality checks, one person at a time...
car will turn over all day, meaning not a VATS issue. It was a NIB Delphi from thepartsladi (EBAY). I sent her an email this morning regarding the issue, havn't heard back yet.
__________________ 2008 Silverado Crew Cab 4.8 (stock) slow
1996 Formula Convertable (not broke anymore 8-4-09) (( BROKE AGAIN 8-15-09)) DEAD slow
car will turn over all day, meaning not a VATS issue. It was a NIB Delphi from thepartsladi (EBAY). I sent her an email this morning regarding the issue, havn't heard back yet.
Well the reason I said rare event of a VATS problem is that the BCM supplies a ground to the starter but it also sends a signal to the PCM to supply a ground to the injectors to cause them to fire. Usually the when there is a VATS problem you have a no start condition. However once, and only once, I was working on a 3rd gen and it was cranking over but the injectors weren't firing. Bypassed VATS with a resistor and it fired right up...
Back on topic...you said that your injectors are not firing. Do you have spark? A easy test would be to have someone spray starter fluid into the TB while you are inside cranking it over. If it starts and runs, then you have other issues than ignition.
__________________ I am kind of a big deal...people know me.
Dishing out reality checks, one person at a time...
no spark at plugs or at coil, fuel pressure is good, the #1 fuel injector noid test is also a tell tell sign of bad opti, pcm, or wirering, because it gets its signal of when to fire from the opti as well.
__________________ 2008 Silverado Crew Cab 4.8 (stock) slow
1996 Formula Convertable (not broke anymore 8-4-09) (( BROKE AGAIN 8-15-09)) DEAD slow
no (blushes), i believe i checked all that would apply but i will check every one of those bastards.
Quote:
Originally Posted by myltwon
maybe a blown pcm fuse or ignition switch?
sometimes a fuse will look good visually but will be bad when checked for continuity
__________________
Quote:
Originally Posted by Arc00TA
My drivetrain has already gone to crap, my clutch is toasted and my 10 bolt is screaming for mercy, when those two go my vibrations will probably stop.
does anyone know if a bad crank position sensor can have anything to do with a no start situation?
I have read that it will not, but my local part slingers tell me otherwise. As far as i know the comp and tach both get the rpm's from the cam sensor (opti). Any help?
__________________ 2008 Silverado Crew Cab 4.8 (stock) slow
1996 Formula Convertable (not broke anymore 8-4-09) (( BROKE AGAIN 8-15-09)) DEAD slow
does anyone know if a bad crank position sensor can have anything to do with a no start situation?
I have read that it will not, but my local part slingers tell me otherwise. As far as i know the comp and tach both get the rpm's from the cam sensor (opti). Any help?
CPS only serves for misfire detection, it won't affect anything.
Your parts slangers probably don't know a lot about LT1's...
__________________ I am kind of a big deal...people know me.
Dishing out reality checks, one person at a time...
Now what???? 
