I believe you may be correct about the problem being the PCM. My 1996 Chilton's for the truck hints at it in the troubleshooting section related to no spark. The procedure calls for a jumper made up with a 0.33mf capacitor to try and trigger the coil to produce spark at the end of the coil lead thus identifying the PCM as the problem. I don't have a capacitor handy. Process of elimination kinda tells me it's the PCM. None locally in any of the parts stores, so I ordered one from Rock Auto. Rock Auto seems to be like Amazon.com for car guys. Recall the "old days" when no spark could be fixed by replacing a coil, magnetic pickup, or ballast resistor? I have a test light and will try the test you describe later on, just to have more data.

 

Well, I am embarrassed to admit I caused the latest "no spark" problem. As per my original post, the first coil was indeed bad, causing various PCM error codes. I replaced the coil with an identical one and installed it and cleared all the error codes.. Did a continuity check for the coil trigger wire from the PCM connector to the coil NEG post. DVM showed 2.3 ohms, which is essentially ZERO for the meter. Then I checked resistance from the coil NEG to chassis ground. Read 2.3 ohms where I should have seen infinity. Read the same thing from coil POS to chassis ground. Coil had an internal short. Turns out I had overtightened the coil bracket, causing the internal short. Loosened the bracket clamp and reinstalled the coil. No more ground. Reconnected everything and the truck started right up. What an exercise.

 

Never heard that before, but glad you got it fixed!

 

Thanks for letting us know. I was watching this thread. I was curious as to what was causing it.