BCdawg57

iTrader: (1)

--------------------------------------------------------------------------------

I am begining to get extremley frustrated with this engine. I swaped a 94 into my 91 camaro.
My problem originated with no spark. I had a brand new wiring harness, brand new coil, a tested good ICM, brand new GM opti, a computer ive never witnessed running.
I did shoebox's opti test, and wasnt getting any AC pulse at the ICM connector. Replaced the opti, and i still get no pulse. I have .4 volts ac at terminal b constantly with the key on. Everything has the power it should.

My computer was tuned by trifecta, which uploaded flawlessly, and when i used his tuner as a scanner i first got code 42, and then code 16. that is when i replaced the opti. Now right now i have no acess to a scanner, but as i said im still getting no ac pulse. Right before i shipped the scanner back i did pull a code 42 again, but didnt think anything of it cause of misc plugs that were probably disconnected. Possible my PCM is bad?

Im at a loss and i dont want to spend 200 on a hunch.

ssean92

iTrader: (10)

do you have the ground connected by the starter?????

BCdawg57

iTrader: (1)

im not sure what you are talking about.

ssean92

iTrader: (10)

this one that says ground to block

BCdawg57

iTrader: (1)

Oh, well i have an aftermarket harness, and the pcm ground is grounded on the firewall.

ssean92

iTrader: (10)

what harness

BCdawg57

iTrader: (1)

speartech

chevyowner02

iTrader: (3)

What coil do you have on it?

BCdawg57

iTrader: (1)

the msd. it wouldnt be the coil though because im not even getting a pulse from the computer. right?

and i just tested the ohms on the 4 wires on the opti harness to the computer, they all read 0.00 ohms.

Klortho

It may be worth trying to find a stock LT1 harness and trying it....

Or give Speartech a call.

If the ignition wiring isn't hooked up properly, you will get a no spark, might want to also make sure the pinouts on the PCM connectors are for the PCM you have, they changed between years, especially if you still had the C100 connector on the harness.

BCdawg57

iTrader: (1)

Maybe i wasnt clear, but im getting good connections between the opti and the computer. I just dont know if this new opti still isnt pulsing or if the computer has a short and wont signal the ICM.

Klortho

have you swapped out the pigtail on the opti?

BCdawg57

iTrader: (1)

Well dont i feel like an idiot.

Yesterday i tested continuity from the end of the opti harness, back to the black connector on the PCM and read good on all 4 wires. Today i decided to do the same to the ICM. pin B5 on the PCM was Ignition Control, a white wire. The wire on the ICM side was lt green, so im like wtf that doesnt make any sence and obviously i had no connection when i tested it. So i call speartech and ask them what the deal is and he goes through the skematic with me and tells me which wire it should be. I tell him i get nothing when i test it with an ohm meter, and the colors of the wires. He then procedes to tell me that i had the IAT plug plugged into my ICM this whole time and the ICM pluged into the IAT.

Needless to say as soon as i switched them it fired right up!

ssean92

iTrader: (10)

Glad to hear it......