What value is sent to the pcm from the opti on the feed wire ? I tried using a test light to see if the opti was sending a signal to the pcm and my test light wont light . Not sure if its a pulsed signal or not . do I have to use a volt meter possibly to test this wire ???

Problem in short , is the rpm signal to the pcm is intermittently lost ...result , when the car is sitting there idling or driving or down the road , the car just shuts off like u turned the key off . Its just instantly dead. Theres no specific time , temp , rpm ect ect this happens , it is completely random . The car has a big stuff 3 pcm and an adapter plug and play harness to adapt the pcm without splicing . Im trying to isolate were the rpm signal is being lost to determaine if its actually the pcm or jumper harness . Coil , ICM , Opti( 2 different ones ) , Opti harness is all brand new stuff and all tested good .

At this point Im at a good spot to isolate this , as the car has went from randomly shutting off , to now ....it will not fire at all , it will just crank .

Thanks for any help

 

Ok , I have more info .

I replaced the ignition switch on the column because I had a spare . No change .

Tested the circuit with a dmm , these were the results .

Coil module :
I had my meter set at 750 dc , I forget how to read it . I assume 24 is not 24 volts ?

....with ignition on
A terminal: 24 dc
D terminal : 24 dc

....while cranking , for ac I had the dmm set to 20
b terminal .10-.16 ac volts

Opti feed wire , reading taken at the pcm connector B3

10.3-10.6 volts

....aslo the injectors are pulsing while the engine is cranking .

Im totally stumped as to why this thing wont fire and randomly shut off prior . Im totally out of ides here ....grrrrrrrrrrrrrrr

 

thank shoebox

http://shbox.com/1/4th_gen_tech2.html#opti_test

 

That is the link I used to orginally to test all the voltages , and yes a BIG thanks to Shoebox ....it helped tremdously today . Everything in this car checks out seemingly fine , and it still wont start . Ive got a brand new GM opti on the car right now , so I took my spare Billet opti that I originally wrongly assumed was bad ....unplugged the opti harness , set the spare opti on the the intake and plugged it in with the key in the run position . spun it by hand and heard the injectors pulsing and the ignition making noise . So that imo , is at least telling me the big stuff pcm is good , the jumper harness is good and everything else Ive checked comes up as good . Took off the accel 300 box and borrowed a friends coil to try , the module is new . With everything else Ive done , I just dont know where to possibly go next .

 

Sounds familiar let me know your results please.