OK, it looks like it is a 42 error, which should be ignition related but it seems to be working like it should. I'll check all connections. Is there anything else I should look for?

 

See Attached Files. Code 42 has to do with Electronic Spark Timing. I ended up doing all the checks but I had to re replace the EST module that is mounted on the firewall.

It is a pricy item:
https://shop.advanceautoparts.com/p/...72+OR+25988090

 

The first time I had code 42 I replaced the EST with one from the junkyard and it worked well for years and it was cheap.

 

Aaaahhhhh, and finally this problem has been solved. I got three bad distributors out of three distributors. After rechecking and greasing all of my connections, I put the recently replaced ICM from my 30 year old distributor on and viola, no more CEL. I would say that the truck also runs a little better than it did with the one on it that came with that rebuilt Cardone distributor. My first distributor from NAPA was new mfg made in China and it activated the spray nozzles at key on. My second was a rebuilt Cardone from NAPA and the screw holes didn't seem to line up with the cap and then, one of the inserts for the screws fell out and into oblivion. Third distributor from RockAuto is a Cardone rebuild and it seems to have come with a defective ICM. It was a closeout and pretty cheap so I went for the ICM swap and got lucky.

Thanks for the help. I now know my ignition system pretty well.

 

Ghlad you got it resolved. It can be a real PIA troubleshooting when you have defective parts. My 89 S15 Jimmy engine was out of my vehicle for almost 2 years. I went through Fuel Pump, Fuel Pressure, no spark, crossed plug wires, leaking fuel pump. While the engine was out I installed new Edelbrock camshaft, Used Edelbrock Intake Manifold, New Edelbrock roller timing chain, new rebuilt 94 heads with roller rockers and 1.51 rocker ratio. I struggled through all these issues and finally got it running but it was misfiring. I took it to a shop and I could not believe it but no matter how many times I went through the firing order i still had a crossed plug wire. Before that, I pulled the heads and visually checked the distributer installation and realized I had the distributer in 180 degrees out. Now the Jimmy runs great. Has more power and throttle response than it ever did and I have the Jimmy in for paint.. It has been a very long and hard road.