bandrews239

I have a 95 that i have put a low milage 96 motor in. I have evrything back together and i have narowed it down to no spark at the coil. I replaced the coil, and the icm. im stuck does anyone no how to test to see if the computer is sending the signal to the icm.

jaa1992

Did you check the fuses?
IIRC there are fuses for ECM, INJ 1 and INJ 2. Mine once ran like crap after going over railroad tracks and it was only pulsing 4 injectors Replaced the INJ2 fuse and all was happy again

lt4red

http://www.camaroz28.com/forums/showthread.php?t=601565

This link describes the test for finding out if the ICM is telling the coil to fire. You test at the ICM plug with a meter set to AC volts. It should vary as described while cranking the engine. If it doesn't vary the voltage, then the problem is the opti/ the opti harness, or the PCM.

desertmike1

This forum has several, very Knowledgeable guys on this subject...hopefully they will weigh in.

Do you have a FSM?

bandrews239

Thats the artical i was looking for, I will test it in the morning and post my results thank you for all your input. yes i already checked all fuses.

Richard Church

lt4obsesses

Are you using the '95 or '96 ecm? '95 = OBDI, '96 = OBDII. I'm just throwing this out there not being exactly sure what specific effect this would have.

pcolt94

This is a good link and what I would recommend also for troubleshooting. If there is no AC voltage to the ICM at pin "B", then it would relate to a PCM or opti problem. Although these parts could be bad, it could be anything also that relates the their proper operation.

In addition I would check for fuel injector drive using a noid light. This is important because the opti is the clocking pulse and drive for the PCM to develop the injector drive. If there is injector drive, then you can forget about the opti (for now). Check the AC to the ICM and anything that is missing. If there was no injector drive, then the PCM or opti could be the problem (or related item).

Obviously make sure ALL fuses are good especially the ones for the injectors and PCM. There should be 12 volts on one pin all the time (key on) of all the injectors.

Was the motor known running before you did the swap? Did you have the opti off?

Check all connectors on the PCM and opti for corrosion, bad connections and proper seating.

bandrews239

I am using the 95 ecm because i have all of the 95 sensors in. I found one dead wire from the pcm to the icm (terminal D on the icm). I replaced it and now that wire is bringing in 11.5 volts.Terminal A is only bringing in .5 volts. still no spark at the coil. I do have a pulsing ground at the injectors so i know the optical sensor is working. Is there a way to test the pcm, or somewere i can take it to be tested? I replaced the opti when the motor was out, along with plugs and wires. I believe terminal A should also be at 11.5 volts. does anyone no Why i would be getting such less volts on this terminal.

pcolt94

Pull off the connector on the ICM an measure pins A & D in the connector. They should be both 12 volts (key on). It comes from the coil via coil fuse #25. Pin C should be ground and pin B is the AC drive from the PCM.

If you only have 0.5 volts on pin A of the ICM connector, then either the coil is open, there is a bad pin connection (at coil connector) or the wire or connection to it is defective. If you measurement is correct, then this is what you need to chase and correct first (it may solve the problem).

Correct the known problem first, don’t focus in on the PCM at this time. However I would check the AC voltage drive at pin B at the ICM connector. If it is there, then you can eliminate the PCM. Don’t forget, you have to crank the engine to measure this voltage.