What is the simpliest way to determine if my PCM or the opti is keeping ignition coil from being able to fire ??? Could I try another PCM without getting car towed to shop to reflash ? I have no pulse on the ignition module connector when car is cranking. I do have 12 volts on the pink and the green wire with key on....I also have a good ground on the blk/wht wire with key off but this wire also shows ground with key on ?? NO fire from ign coil..

 

I would personally not consider flashing the chip for this at this time. It will just bring in another variable. How have you determined there is no pulse to the ignition module connector, meter or scope?

Your ground and voltages are good.
You could try another PCM

Ignition key off, remove Ignition Module connector.

Set meter to read AC volts and connect probe to terminal B – white wire. Have some one crank engine, meter reading should be between 1 to 4 volts. If you use a scope it will be about 5 volts. If you don’t get it, you are on the right track probably. If the voltage is there, the ICM could be defective.

The PCMs are pretty reliable (better than ECMs) and would not suspect it as my first choice. You can probe the low and high resolution pulses from the opti but do need to use a scope. Everything must remain connected. I usually slide a pin down along the wire into the connector at the opti. You can then attach the probe to the pin. The low resolution pulse is the important one which is need for engine run, the high is used for timing. Pin A, red/black is low resolution, pin B PPL/wht is high resolution. Pin C Red, is 5 vdc.

If you don’t have the low resolution, the opti probably is the problem. If you have the pulses, look to the PCM. It could be bad or check the connectors on it.
Charge on.

 

I'm having a similar issue. The only thing I know, for certain, is that I don't have spark from the coil. If I find anything, I will let you know.

 

What engine are you running in your 96, LT1 or LT4?

JAKE

 

I have an LT-1. I checked pulses at the ignition mod with my AC meter and got no volts. I did this with everything hooked up except the ign mod connector. But my procedure said to disconnect the Tach but I don't know where. Would it matter if tach is connected or not ? I also do not have a tach reading but I had one. I lost the tach after fooling with ign mod and ign coil and checking sensors and grounds. The ac pulse reading was checked on the white wire at ign mod con. If the PCM was bad or wires to it bad, then could I also not get an AC pulse ? I also hooked my scanner up and it is linking to three systems but four systems are not communicating, this is why I beleive it may be the PCM vice the opti. Can the opti function and put out AC volts if the computer is bad or totally disconnected ?

 

Reason I asked:

A few weeks ago I had Brian at PCMFORLESS.COM burn a PCM for me. Instead of sending my PCM, which works flawlessly, I opted to spend the extra $$ and have him send me a complete PCM with the new programming in it.

I now have the factory PCM for my 96 LT1 Vette boxed up and Brian's installed in my car. You may have read my posts on how pleased I am with his programming.

If after you've done all the testing you can, and if you cannot find a 96 LT1 Vette PCM locally, I can send you mine to use for testing, just to eliminate the PCM as the possible cause of the problem.

I MUST have it back though. So If you're willing to pay the shipping costs involved in me sending it to you and you returning it to me, let me know and I'll send it.

This is what Forum members do for each other, right? It's about trust.

Jake

 

I couldn't respond to your email because the Forum informed me you had opted not to receive exmail.

To answer your question, all you need to is disconect and unplug yours and plug in mine.

There are two screws and four plugs which are color coded. It's a really simple swap. You won't need to have anything done it mine, no reprogramming or anything like that. Since we both have the same year (96) and model, (LT1) Vettes it may take you all of five minutes to make the switch.

If you want me to ship it to you, I can do it tomorrow. Just email me with your address - jcameron266@sbcglobal.net

Isn't retirement nice? BTW, my son, Ryan, is a first year Cadet at West Point.

Let me know,

Jake

 

I shipped my PCM to you via USPS Priority mail yesterday. Lady said two to three days so you should receive it Wednesday or Thursday.

Keep me posted on how it works out for you.

Jake

 

OK will do, Thanks