Mine would crank over and start some times but only on 2 or 3 cylinders and run that way!!!WTF. If I tried it enought times it would run right.

A good way to prove it's the switch is to turn the key on and off all the way and keep trying to start the car, it may start!!!

 

Maybe I missed the answer.... but I'll ask again - how are you reading the PCM codes?

(NOT "how are you testing the Opti?")

 

ignition switch

 

Fred,
The only time I was able to get any code at all was when it was running sporadically. I had it at the parts shop and they pulled a P0300 off of it and that was it. I went home, replaced the plugs and wires and reset the SESlight by disconnecting the battery and then replacing the cable.

I haven't had a SES light on since and of course I can't drive it anywhere to see if I can get it to come on again.

Really an ignition switch can cause all of this???

I wouldn't be surprised since it "just died" that day and now everything is new. What is wierd is that it did restart with all the "old stuff" reinstalled 2 weeks or so back. Then I let it run for a good 30 minutes in the garage and when I went to restart it later that day....absolultely nothing. That's when I started replacing the ICM and Coil with the GM units.

Thanks,
Ivan

 

I think that my lights are doing the same as yours did!

WHen I attempt to start they go out, not dim....

???

Maybe,
Ivan

 

The code for loss of low resolution pulse form the Opti will not turn on the SES light. It will prevent your engine from starting. You can get a cheap OBD-II code scanner for less that $50..... cheaper than some of the parts you have been throwing at it.

 

The key even felt stiff when i was turning the key back and forth. It does alot of weird things?????
The dash lights just go out when you turn it forward to ingage the starter and then c0me back on when i let go of the key.

 

Gonna get a scanner tomorrow then. I was always under the assumption that if I was getting 1-4vdc from the PCM to the ICM that I was receiving proper pulses...probably not then huh?? Cool. So it's possible that the new Delphi Opti has taken a dump?

So Scanner first then maybe it'll nail down the issue. Then we'll bark up the "ignition switch tree" if we have to.

Thanks Fred,
Ivan

 

Alright FellaZ.

Took Freds advice and picked up a scanner today.

Just pulled:

P0102 Mass Air Flow (MAF) sensor circuit low frequency
P1351 Ignition Control (IC) circuit high voltage (open circuit )
P1371 Distributor Ignition (DI) low resolution circuit

I'm really freaked out thinking that the new Delphi Opti "took a dump" but at the same time, optimistically hoping that its the ignition switch that isn't supplying power to the whole setup.

I picked up a new ignition switch on the way home as well so....??

I'd really like thoughts before I take the time to drop the column and replace the switch.

At least I"m on the correct way to recovery....

Thanks,
Ivan

 

Clear the codes by pulling the "PCM BAT" fuse for 30 seconds, then see how fast the P1371 reappears. That will tell you if its the Opti that is preventing it from starting. It isn't unusual for that code to set from time to time. But if it doesn't start, and comes back immediately, you will not have a lot of options. Remember also that a faulty harness, corroded Opti connector(s) - there are 2, damaged pins, loose connector, etc will also set the code.

 

Here is a link to a 96 Corvette service manual Distributor Ignition Description and Check flow chart for troubleshooting. I've found it to be useful, if a little hard to read. It also talks about a scanner, but a multimeter will work for most of these checks. The pages are numbered to keep track. The wiring schematic, and wire colors, is a little different on an f-body, however, the connector letters A B C D on the opti plug and the ICM correspond to the F-body. Which means these circuits do the same things on both cars.

http://s88.photobucket.com/albums/k1...77/DI%20CHECK/

From the low-res code, it sure points to the opti, or the wiring. The IC circuit code is set if the voltage on the IC circuit exceeds 4.6v. This is on terminal B on the ICM connector. This is the one you check for 1-4v while cranking. Were you seeing anything higher than 4v? This code really only points to a bad ICM, bad ground to the ICM, or bad wiring.

 

Righteous. Cleared the codes...Pulled the fuse....

Attempted to start the car again and still nothing. And there are no codes after rescanning it...SES light still off.

I'm gonna try and check some more of the connections upstream. I'm still thinking that it's gotta be something along the lines of the supply power or power (signal) that the ICM needs to fire.

Could this be pointing moreso to the IGN switch now???

I'll also check out the Vette link as well. Thanks for chiming in and I'll let you know tomorrow after I get off work and get a chance to work it out.

Thanks fellas,
Ivan

 

edit:

Man, those would be helpful as hell if I could read em a little better!! LMAO....going to try and look at em since the printouts were shoddy. Could be my printer. lol...

Excellent info and if I were anyone here of importance Id say that the flowsheets (once they became more legible) would be stickys FO SHOW!!

Too many ICM/COIL/OPTI problems to ignore the importance of the documents you provided.

/edit

Thanks for your info as well. I don't remember seeing any more than 2 .xx volts to be honest. The ICM is now a new GM unit and I hadn't cleared the codes prior to installation so those coulda been thrown prior to it being installed (from the old failing ICM).

Seems like wiring could be of concern. I did check the pigtail out from the Opti. Testing resistance between the four lines I found good connections and lines. Maybe on the "downstream" side from the PCM is where I need to start looking.

I'll also look at the grounds as well.

Thanks again fellas, I'll sleep better tonight,
Ivan

 

I tried to upload some better images in the link. If you have any more problems, I could send you the originals, which are pretty good, so let me know.

 

Oh for sure I would love the originals...

Could ya email em to me???
ivan_christa@msn.com

Also, what the hell do I need to be looking at now that I got codes??

Should I rock out that IGN switch or am I barking up the wrong tree all together??

Thanks,
Ivan