I am trying to deterimine if my opti spark on my 97 Transam is bad and i have tested the white wire going into the icm and i get no volts when crankin the engine. I am trying to figure out how to test power coming from opti spark to computer. There is no SES codes showing up. And this problem all started after i did a plug and wire change. Any help would be apprecitated Ive read lots of threads of opti sparks going bad but can't find anything that helps in my situation. Thanks

 

Just to clarify there is one Opti spark distributor. Check the 'How to diagnose a bad opti' sticky at the top of this forum. According to that no volts at the white wire indicates a bad coil or ignition fuse.

 

What problem?

 

Ive read the sticky and done everything, its says to to check the power to pcm and harness im not sure how to go about doiing that. It was my understanding that if there is no power to the white wire on the icm plug while crankin(one to four vac) then that means there is no power getting sent therefore its not the icm or coil.

 

the car has an intermitten starting problem were it has no fire but will crank over and its getting power to injectors.

 

Remember that the white wire goes from the PCM to the ICM. Therefore, you don't know if the PCM is not sending out the signal or if the ICM is merely grounding it. Try unplugging the ICM and see if the signal is there. If so, the problem could be the ICM. If it's not there, check at the PCM.

 

i appoligise for confusion i understand the opti is one distributer with the optical cam position sensor i was at work and called my wife and had her post the thread thought she typed word for word im just now getting home from work as i read it it sounds very un educated but i am not an expert nor a mechanic thenks for the help

 

thanks for reply i did check the white wire plugged and unplugged both ways nothing just dont know how to go about checking pcm and power going into pcm. on shoebox's diagram it shows opti harness going into pcm as ( b3,b14,b20, andb2, andfrom pcm to icm as b5 where on the computer r these wires exactly and is that were i would check for power thanks for your help

 

just a little history i got the car from a freind who built it. its been about 3 years since he started its only seen about 500 miles since its a built 355 trick flow heads comp blower cam vortec s trim 60* inj pcm for less tune as far as i know its the original opti with 82,000 miles with msd cap and rotor when i got it it was running with a o2 sensor ses fixed that and found 3 burnt wires and some fouled plugs so i did the otvc kit and new plugs started up and ran fine i drove it about 25 miles stopping twice inbetween when it died at a light then i made a few miles down the road when it stumble a little i got on it a little and it blew the plenum elbow off so i finaly got it home and it wouldnt start so it sat for a day started up drove it to get gas started fine got home next mornin wouldnt start again and thats were im at sorry this was so long but thanks for any help

 

so turned the key when got home and fired up shut it down tried it again and just kept crankin so grabbed the multi meter unplugged icm had my wife crank it over i saw 0vac first crank second showed 2 vac third 0 fourth 1vac on the white wire and my computer reads no trouble codes if the opti doesnt send the signal to the pcm wont it always throw a ses code or is that just obd1

 

so idisconected the opti harness on pass side intake next to fuel rail fit some paper clips inline with the to pigtails so i coud test volts while cranking (not sayin its right but thats all i could come up with.) alright so wire A red/black 453 is showing 2-3vac while cranking , B purple/white 430 also showed low volts 1-2 ac im not sure if thats what i need but the opti is sending a signal so what now any ideas i swear 1 out of 6 trys it fires

 

Like Speedy said,problem could be with the ICM..take it off the car run to Autozone or O'reilys and have them test it for you.

 

Did you also check the voltage on the red/black wire (circuit 453) and on the red wire (circuit 431)?

Are you actually checking the PCM for codes, or are you just looking to see if the SES light is on? Both OBD-I and OBD-II set codes for failure of the high resolution (430) and low resolution (453) pulse signals.

 

I checked all four wires for voltage. two of them had zero volts and the other two which are A red/black 453 is showing 2-3vac while cranking , B purple/white 430 also showed low volts 1-2 vac. And i have a scan tool and i scanned it to check for trouble codes and it came up passed..no codes available. If im getting volts on my high and low resolution wires does that mean my opti spark is good? Thanks for your reply.

 

Loss of either the high or low resolution pulse sets a code.

You appear to have a variable voltage on the two signal wires. Odd though that you don't have anything on the 631/red wire. That's the 12V power supply to the Opti optical module. It wouldn't be putting out a variable voltage on the 430/purple-white or the 453/red-black if it wasn't getting 12V from the red wire.

632/pink-black is the ground, so "0" on that wire is normal.