ponchoV8

Where is a common area of the ignition wiring circuitry that fails? Is there anything under the dash area I need to look over? Any junctions, plugs, harness, etc. that you guys have experienced as a common spot for an open or corrosion to occur? My problem is that my '97 Z-28 died a little over a month ago. It cranks but doesn't start. What happened is that for about 4 months the car would take at least 2 trys before it would fire. One day I became annoyed enough that I figured I would change my coil to try and fix it, but the problem remained so I figured I would wait to save up for a Delteq. Unfortunately the next day after replacing the coil my car fired up, sputtered and died and would not fire again.

I followed Shoebox's website as well as my factory shop manual and according to both, if ONLY ONE of either the "A" or "D" terminals on the ICM plug has less than 10V, then I have to check for continuity of the ignition related wiring; it is the "D" terminal that has less than 10V DC. My "A" terminal is showing 10-11V DC, in addition my "B" terminal shows 4-5V AC while cranking. I don't wanna replace the Opti just yet, since I guess that since my "B" terminal is within spec, the PCM is still receiving data from the Opti, plus I scanned the car and no codes are showing. I also replaced the ICM and still no luck. I've also checked the fuel pressure and checked the continuity of the Opti harness to the PCM and all is well. I bypassed my V.A.T.S. a while back when the Security would come on and the car wouldn't start, but the light is not on and hasn't been on since I bypassed it. My new coil is an Autozone Duralast brand and my new ICM is by Wells. Plugs and wires were changed about 2 years ago. I'm lost folks, next stop is the dealer.

97LT1Boy

To The Top!!!!

This is the same problem I seem to be having. My car will crank and crank, but not fire. It isn't getting any spark, I put some wire from the coil and it didn't jump to ground or anything. No plug wires gave spark. However, mine differs in that when I tried to scan for codes, my scanner fails to even connect to the cars computer. Also, when the key is on, the low speed fans turn on continuously and the SES light lights up. Is this a failing PCM? The car was running fine before, other than missing under load which i assumed was from the water pump change the and Opti probably getting some water on/in it. I wasn't worried, and figured I'd just drive it nicer until I could afford a new cap and rotor. More information would be GREAT though, I don't want to jump to conclusions and end up with parts I don't need and can't afford right now

cammed_aro Z28

not to aid in the hi-jacking of this thread, but i mysteriously lost spark the other day also.

Guest47904

First if A on the coil or the ICM is at 10 with the KOEO, you have a problem. It should be battery voltage. Check across the battery and see what you have. Then trace from the ignition fuse on the pink wire to connector C100 (the black 10 pin connector near the PCM). ONce you have that resolved, then check the voltage from B of the coil to D of the ICM for battery voltage with KOEO.

It's unclear if you checked the B terminal of the coil or the ICM. When looking for IC signal the white wire is the one you want to test for 1-4 VAC when cranking going to the ICM.

ponchoV8

Well, I went to the Chevy dealer because I couldn't bear to wait anymore and my options for self-diagnosing this car ran out. Had it towed there. They diagnosed it the next day (for $78.68) and told me that it was the Opti afterall. In addition they say my plug wires are coated with oil and need to be replaced. They said that to do just the Opti and wires would be $1726.00! The service advisor recommended that I also change the waterpump while they were at it and that would bring the total to a little over $2000.00! But at least the waterpump has a lifetime warranty! Meanwhile, my dad whose a mechanic for the past 20-something years told me before hand that it was most probably the distributor too. Doh!

Needless to say I had the car towed back and just ordered a new Opti and Meziere electric waterpump for $500.00 total from Scoggins-Dickey. I wanted to get a Dynaspark distributor but they're backordered until early next year, and a Delteq is worthless without a functioning Opti, so that's out of the budget for now. Towing back and forth cost me $170.00. I'm also gonna do my intake manifold oil leak at the same time. So a little grease under the nails and a lessoned learned from an old man is better than shelling out 2grand to some ripoff dealer. Good luck with you guys' probs. Oh and one more symptom my car had before it died was that it would hesitate past 5K rpm, so I'm assuming that was also part of the problem.

ponchoV8

97LT1Boy, I was looking up your problem on my Helm '97 Camaro shop manual and basically if you are not getting scan tool data, you have to first check various terminals on your Data Link Connector (DLC):

1) Check DLC terminal 16 with a test light to see if it lights up=

-if no light, repair B+ circuit to DLC terminal 16, if you still can't get a reading, the manual says to go to Powertrain OBD System check.

-if it lights, measure the resistance between DLC terminals 4 and 5 and chassis ground for 5 ohms or lower: if it's <5 your scan tool is supposedly faulty; if it's >5 you have to repair the ground circuit to DLC terminal 4 and 5. If you perform either and nothing still happens, it refers you to the Powertrain OBD System check again, which just refers you back to this same chart I hate electrical ****.

You should also check your PCM's ground circuits, battery & ignition feeds and connectors, and make sure your scan tool works by trying it on another similar car. I also thought my PCM was bad on my car as well and I looked up on Madz28.com for a replacement PCM and they have them pretty cheap vs. the dealer.