Z28Roxy

iTrader: (4)

Opti is known good. I'm doing the test with a spare opti that is known good. I have two cars - and what I did was plug the spare opti into the other car's coil wire, opti harness, and 1 spark plug/wire. If I spin the opti with a drill the spark plug sparks.

I switch it to the other car, same test, spinning the opti with a drill and I don't get spark.

Opti harness in the car that is not working has 12v, 5v, 5v, and ground.

Coil harness has 12v and is continuous to the ICM harness.

ICM harness has 12v, 12v, and ground. However, I don't get pulsing ground from it and I don't get 1-4v AC when cranking. I swapped a known good ICM in (the other car's) and it has the same problem.

hrcslam

So both Optis give you no AC voltage to pin b at the ICM?

ACE1252

If all the major components(pcm, opti, ICM, ignition coil) work in the "reference" car, then you have a wiring problem that needs to be tracked down.

Does the non working Z turn over when cranked with the key? That might be the other part of the equation. Are the key on signals okay to the PCM as well? If the car will not turn over, then it is possible that you may have a VATS issue. Are both machines automatics?

Assuming from your sig that both cars are '95. Is the non working one throwing any codes? Have you scanned it?

Z28Roxy

iTrader: (4)

No codes on the non-working car. Non working is a six speed, working is an automatic. Also VATS has been deleted and it does turn over, just no spark.

Z28Roxy

iTrader: (4)

Correct

Kevin97ss

Try swapping the pcm to rule out a wire issue.

ACE1252

The Buick Know how opti video mentions that no codes will set if both the high and low res signals are not pulsing properly.

Since you don't have the 1-4v at the ignition module, I suspect the issue is with the high and low res opti signal wiring(unless the ignition wiring from the PCM is having issues).

Have you verified the high and low res signals(square waves) at the PCM itself? You will need to carefully backprobe the wires at the PCM(with a T pin) and look to see if the waves are present with a scope. You might be able to use a multimeter on the dc scale and see the dc voltage hang around 2-2.5 volts when cranking on both high and low res signals....but a scope is best used...

Simple checks without a scope would be to make sure you have good wiring between the opti end of the harness and the PCM end of the harness.

How did the trouble all start? Intermittent issue that finally crapped out? After some mods were done?

Z28Roxy

iTrader: (4)

All the wiring is good in the sense that it's all continuous from the PCM to the opti and ICM. I did find that B5 (aka pin B on the ICM) connector was loose in the pcm harness because the small white retainer was pushed up a little. I put it back in and made sure the large black plastic retainer snapped over it, but still couldn't voltage. I tried several times.

So I'm wondering if that wire or any other is not making a good connection with the PCM. Tomorrow I will try repinning the black connector with a spare. I also ordered a scope in case that doesn't solve the issue.

This suddenly crapped out, yes.

hrcslam

You need to check for AC voltage directly from the pin on the pcm. If none, replace the pcm.

You can use the pcm from the other car if you have the proper cables and the pcms are the same year (94-95 are the same, but 93 is different). You can pull the bin files off both and load the correct bin after you swap the pcm. EE Hack will let you do this for free (you'll need the ALDL to USB cable and a laptop of course).

IIRC, you shouldn't have to swap bins for the manual tune if using the auto pcm if you don't plan on driving it. But the pcms must be compatible.

SS RRR

iTrader: (2)

Dumb question, but have you made sure the PCM is grounded?

ACE1252

No, that is a good one. Make sure none of the grounds or ground straps are broken. That could cause all kinds of strange problems.

It falls into the broken wires category, but those are critical...well I guess they(wires) all are, but good grounds are a must.

Z28Roxy

iTrader: (4)

Yes it is.

BTW my friend is picking up her turbo SC from your (I think BIL?)

"D.D."

doing osci tests now, will upload some results in awhile.

SS RRR

iTrader: (2)

Indeed. Super Coupes Unlimited Inc.

Z28Roxy

iTrader: (4)

I don't get ANY kind of a square wave from the opti on the broken car.

Can I conclude it's bad?

EDIT: Was not in "denial" about the opti being bad I just thought it was some other problem because I got my spare opti to spark in my other car. I just tested it. Can't get it to spark with the drill.

ACE1252

So you show 5 volts, but no square wave on either the high or low res lines(A and B)?

If so, something sounds screwed with the optical sensor assembly. It's not pulling the signals to ground to give you the square waves.

There is an outside chance that there still could be a ground issue on D, but most likely, the opti is the cause....double check D for a good ground to the PCM and to the battery negative/chassis.

I have seen a video where Gary Doug pulled apart the optical assembly and found broken solder joints in the optical section. He resoldered them and it started working again(it was one of the cheap opti's). I can't remember if it compromised the sealing of the assembly though...

If there is any kind of age on the unit, I'd pop for a new/re-manufactured AC Delco or Delphi.