chevydriverz28

No power at the ignition coil module as instructed by shbox but I do have power at the ignition fuse. Symptoms include no spark from the opti or at the coil. No modifications have been done since the car ran fine. It just started having no fire without leading symptoms. Is there anything between the ICM and the fuse block that could fail besides a broken wire? Thanks in advance.

Brandon

riceburnerZ28

iTrader: (20)

did you check for codes?

RamAir95TA

iTrader: (2)

If the optical sensor inside the opti doesn't send the signals to the PCM (which sends signals to the ICM to fire the coil), then the coil will not fire. shbox.com has all of the diagnostics you need to figure it out, but to me it sounds like the optispark.

chevydriverz28

No, the computer is not throwing codes which is what tells me it shouldn't be the opti. It is a nearly brand new MSD opti billet distributor that worked up until now. The MSD technician I spoke with today said I should be receiving a "high res" or "low res" code. This would suck but be better than the opti. Does anyone know troubleshooting techniques to check the health of the PCM?

Thanks again

x Wild Bill x

Ahh another wonderful thing about the Optispark, it doesn't always throw a code, especially if the car is not running when it starts to die. Have you followed all of the trouble shooting guide in shoebox's guide, like someone asked above? Most important thing to check is whether or not you have an AC signal coming out of the optispark for the ICM. Also make sure the Opti is getting power. If the opti is getting power in, but no signal out then it's deff. the Opti....

Bill

chevydriverz28

Hmmm... ok so checked the supply harness for the opti. It has 12 volts being delivered to the opti with the ignition on. Does the signal return from the opti and travel to the pcm, for the pcm to activate the coil or does the opti signal go straight to the coil? Any ideas on checking the health of the pcm? I have my stock PCM that I'm about to plug in. It's got the factory tune but it should still fire things up the same way. Keep the help coming. I feel like we're getting close.

chevydriverz28

Ok here's another update to my troubleshooting. I tried a second known good pcm and still have the same problem, no spark at the coil or plug. One change to my initial symptoms. I do have 12 volts being received through the pink wire at the ICM harness when the key is engaged, not from any others in that plug though (shbox says two should read 10V or more.) I do not know how I missed this before but both PCM's i've tried have the same symptoms this being included. Still working but any help is greatly appreciated!!

chevydriverz28

One other thing, the shbox opti troubleshooting steps are a great start, I'm running into differences between his 95 LT1 instructions and the wireing my 96 LT1 is presenting, both in colors and number of wires. If anyone could help with 96 specific tips that would be great. Thanks.

chevydriverz28

OK, I've naroed it down to one thing. I've got power where I should at the coil, only thing is I have no signal coming from the ignition control (which is controlled by the opti spark talking to the pcm, to fire the coil. Any tips? I really want to make sure it's the opti spark before I go through all the hassle of swapping it. I really didn't have any leading symptoms, the car has never seen water, never leaked coolant, and the entire motor and electrical system has less than 400 miles on them. Plus MSD said this was the second generation opti from them that replaced the "piece of crap" they made before. Sigh... can you tell i'm reaching out for help yet? lol

garage_queen

iTrader: (3)

the ICM won't fire the coil if it's not receiving a signal from the opti. I just recently fixed a 93 with all the same symptoms you are describing. When I opened the old opti, the backside was full of oil from leaking seals in the timing cover and the opti itself. Also, be sure to check the harness that runs from the side of the intake down to the opti connector. I've had a couple of these harnesses go bad as well and cause opti failure symptoms.

xx_ED_xx

iTrader: (17)

opti's are like hei modules. It is good to have a spare

IronOutlaw

iTrader: (4)

Get the icm tested first. Make sure they use the right adapter (the one with the ground) for their machine.

Also check the opti harness and every wire going to the icm and the three wires going to the coil.

The opti is blamed alot when it's not the problem. I like to exhaust every other option before replacing it.

chevydriverz28

Thanks for all the help. I have checked everything and all the wiring at the coil is acting as it should. I have tried multiple coils and computers to eliminate them as the problem. I am running the MSD Billet Opti, it eliminates the wire that plugs into the distributor and has a harness that travels up the front of the motor up to the flat plug next to the intake. Again, all of these things are only 200 miles old. I just contacted JEGS and even though MSD wouldnt do anything for me since I was 6 months past the manuf. warranty, JEGS said they honor all sold products with a 3 YEAR WARRANTY!! I honestly was blown away at the customer service and have to stand behind them highly.

Thanks again for everything and I'll keep you all updated.

MavsFORMULA

iTrader: (4)

Check that ICM for sure.. Less than ten min to pull and free to check at auto parts store. Also make sure they use dilectric grease for testing, and you do for reinstallation, or it will be bad for sure.