I am having trouble getting my LT1 to start.

I have ruled that it is a spark problem. All the parts are new except the ICM.
Is the coil supposed to be putting voltage to the opti at all times when the key is on?

 

The coil does not provide voltage to the opti (except through the coil wire to fire the plugs).

http://shbox.com/1/95_ign_system_schematic.jpg

 

Right, but is that wire always hot or just when the coil gives the signal to opti to fire?

Im trying to diagnose my no spark here, the only parts that are not new is the PCM and the ICM. ive already gotten the ICM tested and its good. I did the opti test via your page and i didnt get any ac current. Now i guess its down between the opti and the PCM. I really hope its the PCM....

 

The only time the high tension lead has power is when the coil fires. Engine has to be running and it will fire very rapidly. It's not something you could measure with a standard meter, since the voltage is so high.

If you are not getting any firing pulses at the ICM plug, it's probably the opti or the opti harness. PCMs rarely go bad.

 

is there a way to test opti harness? just measure resistance?


I measured the ohms on all wires on the opti harness and they all read 0.

I tried the test again, and there is no ac voltage. I reversed the leads and got 24 volts though?

Would this test be the same if the harness is from speartech?


Im not getting any spark from the coil either, im not sure if this is becauses of no pulses or not(probably) i would much rather my pcm be bad though

 

I used trifecta's tuner to try and pull error codes out of the pcm, and it gave me an error message? Said there was an error trying to pull codes from the pcm. What does this mean?

 

Is it possible to hook up a noid light to the opti harness to see if it is pulsing when it is being cranked? I need to know if there is a way to test the opti without having the signal go through the pcm first.

thanks