1995 GMC C1500 electronic spark control

The module in the distributor MUST ground to the chassis of the distributor. Are you having a problem with it starting or staying running? If it runs, does it run GOOD? Those things are known for going bad. Usually they won't run at all, though. Stranger things have happened. Have you tried replacing it? That would be my recommendation.

i put a new module in dist. did not help. was told it might be pickup coil what do you think

Yes, that's also a possibility. If it's missing badly, have you checked the plug wires? Can you narrow it down to which cylinder is actually missing? (or cylinderS)... You can unplug the knock sensor and never know it. The only function of the knock sensor is to detect spark knock or pings and retard the timing until the 'ping' goes away. I've broken them accidentally while replacing the starter and just forgot about it.

If it runs, the module is working. Does it have 'throttle body injection'? There will be 2 injectors in the throttle body. I can't remember exactly what year they changed the fuel injection. Get back with that info so I'll know if we're even on the right track.

new cap, wires, rotor, module,pickup coil,code still comes back.electronic spark control but truck is running better.