I own a 1989 GMC Suburban 5.7 Vortec 500,000k miles. We were setting the timing with the ignition running the ICM was plugged in and the ignition stopped running. Now it only cranks with no start. I'm thinking a in-line fuse or cur cute?
Thanks
Brett Higginbotham
Well the good news is that's a bypass ignition system and it doesn't use the PCM to control the coil during cranking.
(the PCM controls other things like fuel, but you should still get spark while cranking).
Whether during cranking or running (above 400 rpms) the signal to the coil always goes through the Ignition Control Module (ICM) (on your distributor)
So you need to check for spark during cranking.
Pull the coil wire off of the center of the distributor cap and put a spark tester on it.
Crank the engine, You should see spark.
if you don't see spark then make sure you coil is getting power.
There's 2 electrical connector plugs on the coil. Both have pink wires on them. The thicker pink wire on the grey connector is your power wire. (it should have around 12 volts)
[you can see it there on the wiring diagram (GRY CONN)]
This same circuit powers your ignition control module so if you have power there you should have power to your ICM.
Perhaps one of those 30 year old wires on one of the plugs to the ICM got loose/broken/grounded as you were messing around with the distributor.
Carefully check the connectors and wires going to the ICM on the distributor.
If you have power to your ignition coil, and all of your wiring checks out fine, then perhaps your pick-up coil chose this coincidental moment to fry.
