OK. This is good. Refering back to diagram from post #31, you have verified that the 10A fuse back to ignition is good and that this voltage(12V Bat) is showing up across the primary coil windings.

OK. This is good. This AC voltage that you are seeing(2.5 to 2.8V) is the RMS value of the 5V pulses which are coming from the PCM to the ICM. The RMS value will be about half the amplitude of the peak to peak voltage(again 1/2 X 5V). Since this voltage is what you expect, the inference is that the Opti is GOOD, because the PCM has to detect and syncronize(ie knows the crankshaft position) the High resolution pulses coming from the Opti before it generates the pulses that go to the ICM, which are timed to fire the coil at the proper time.
What "other" white wire ???????

Yes, you could have a faulty ICM. Suggest you remove and have tested at autoparts store. The tests that you have performed only check the voltages and signals going to the ICM, but to not test the ICM itself. You could also have a faulty coil, but coils are pretty rugged little buggers, and usually don't fail. The ICM, which has integrated circuits inside, is much more prone to failure than the coil.

I think you are getting there. You are ambitious for sure !!! Keep up the great debug work !!!!

 

My advice is if your PCM is visually damaged & tapping on it causes weird things to happen-replace it & then start from there.No sense testing things when computer is obviously bad.Tapping on the computer is an actual test for computer & computer operated parts(automotive).Get that computer replaced first

 

man I wish I could help but I can hardly help myself.
you sound close

 

Hi Jaa
thanks so much so nice of you, so very nice. I live on Long island. Id be happy to pay shipping both ways of course My car is a 1993 6spd my ecu part number is 16159278 If that is the number you have Id be happy to pay you to let me try it if I need to. I still have some tests I want to run and yes I did check that harness wire to the opti. Im gonna check the coil wire tonight to see if its getting spark. There is a lot to do with testing so Im gonna keep testing. My friend can get me a good deal on an new ecu if needed but to be able to check with one would be really good. So if in the future I am down to needing to check that I would be eternally gratefull. Hopefully it wont get that far and Ill fix this soon I mean it could still be the coil a wire the icm so Im not ruling any of that out and the guy I bought the opti is sending ema new one but if after all this work goes on and its still not starting I guess the last thing is the ecu which I am hoping to avoid. With that thank you so much for the offer and if I need it and its ok with you ill be glad to pay you for the opertunity to check it out. Thank you so much really its impressive how many nice people there are on here

PS and yes I am going according to shoebox checks great site

 

Thanks so much I am learning a great deal. Yeah I figure the opti is good because of the a/c voltage. the other white wire on the ICM is supposed to check out to ground and I tested it and it is testing to ground and tests out with continuity tester so I know its not a broken ground but like you said the ICM could still be bad and from what I undrstand the guy put the grease or whatever it is behind the icm after the fact which they say can cause them to burn out. Im thinking this could very well be the ICM at this point

 

Question Al Boreman

You said in the upper post 41 ' OK. This is good. Refering back to diagram from post #31, you have verified that the 10A fuse back to ignition is good and that this voltage(12V Bat) is showing up across the primary coil windings'

I havent tested this fuse as of yet but if the primary coil windings are showing 12 volts each doesnt that infer the 10A fuse to the ignition must be good or is this a seperate circuit that needs to be checked also. I so appreciate this help. I must be getting close my money is starting to think its the ICM for some reason I still have to check a ground off the coil to make sure its not broken

 

Awe thanks buddy so nice of ya. Well this is the price we pay toown oneof these but thank God for everyone on here who are so helpfull. Without this i could not get a lawn mower started so I know how ya feel lol Glad to see you got that pully off that was a killer I know

 

BTW I love the color of you vette

 

Thank you and so does the guy I sold it to that is my old one and I had painted it myself. I sold it today actually and the one Im working on is the new one i got and when I get it started Ill take it out and get some good pics of it. That was my old 1991 automatic. I now have a 1993 6 speed with the famous optispark lol I havent evenheard this car runs yet I bought it this way so its a bit of an issue but Im getting closer now so I think it wont be long before I hear broooommmmmmmmmmmmm Hopefully

 

Well I think I have narrowed it down pretty well. I checked again for pulsing ground at the fuel injector and I am getting that also so it looks like the opti is good being that I am getting the correct a/c voltage at the ICM and Im getting the pulsing voltage from the fuel injector. I am not getting a pulsing ground however from the ICM to the Coil so it looks like this is the reason why it wont fire up. The coil needs to see a pulsing ground. I have to wait till monday to get the part as it has to be ordered
wow this has been a lotof work but I learned a lot about using a tester and volt meter and I understand the wiring of the optispark and ignition system a whole lot better lol

Hope it starts when I get that ignition coil, Im almost sure it will cant wait to try. If anyone lives here close by on the Island and has one let me know lol

 

Correct, your tests "infer the 10A fuse to the ignition must be good" , so no need to locate and test the 10A fuse.

 

Yep, without that thermal compound, they can burn out in a few heart beats.... Did the previous owner forget to put this on the back of the ICM module? Did he put it on AFTER the engine dies in hopes this would fix it ??

You meant to say ICM, not ignition coil, right ? Anyway, you can take the old ICM off and run over to almost any decent auto parts store to have it electrically tested.....

 

Al Boreman
Yep, without that thermal compound, they can burn out in a few heart beats.... Did the previous owner forget to put this on the back of the ICM module? Did he put it on AFTER the engine dies in hopes this would fix it ??

Yep and he said that to me ( That he put the grease on the back after hoping it would start )and it is my suspicion that he did not think that it could be the probrem again as he had just replaced it not to long ago. Now that I see there is no pulsing ground from the icm to the coil I am led to believe this is the problem and yes I meant ignition control modual not coil I better updater that lol Im tempted to just go out and buy one but my parts guy who knows me well will get mea good deal with a lifetime warrenty so Ill just wait till monday but am I just dying to put this modual on. Thanks so much al Ill be posting the results soon enough and if I see a good deal somewhere Ill just buy it before monday lol ttys

Mike

 

Sometimes the people will take the connector loose and shove it up under the dash. Don't aske me why. You might need to take the cover off from under the driver's side of the dash. The OBD plug should be there.
93cruiser

 

Thank you
yes I found it hidden up underneath. It will be reinstalled correctly

 

Well I had it running...........Yep had it running, for about 5 minutes. strange then it shut off and I could nto restart it. I did go out and buy the ICM modual and when I first went to start it it did not start. The battery is so dead in the car that it has to be boosted and you can boost it for a half our and once you remove the ccable wham its back down very dim lights. Needs a full charge or a battery I suppose
I once had a car that would not start with a boost unless the battery was putting out a full 12 volts. If the voltage was below 10.5 on the battery for some reason it would not start. Once I put a new battery in it the car would start no problem. Long shot but wondering if this very dead battery has anything to do with it

I will say this though I got to hear the motor and it runs well. No noises or anything liek one one look for when first listening to the motor. At this opoint there is only one more part t replace and that is the one part I have always suspected, The PCM

Im gonna walk away from it for now and ponder the fact that one I had it running so I know it runs lol and where to go from here. Ill wait to hear some suggestions and go from there. Any thoughts
Oh and when it started I was shocked lol and so happy but then as we know it shut down which is the problem he was having. so with the new opti new ICM and New coil what is left ?

Mike

 

Wow your almost there

 

Hm yeah, at least I heard it run. Im sure at some point Ill get this thing running. I am closer and learning more and more as I go and at least one things is for sure the motor is good. I was hoping to take it for a test spin around the block but as we know it shut off damn lol

 

A weak battery will definitely cause issues. Maybe your next move is to fully charge the battery, load test it, and replace it if it is marginal.

 

Yeah I agree based on limited knowledge I have i think many sensors need to see a certain battery reference voltage. Im gonna take it to get tested today. I noticed it started after having my truck boosting it for a half hour, then when I hit a few accesories is when it died. While I have the battery out Ill clean up the ground post that is there I believe and any other terminals