After installing a new trans dip stick tube in my 90 f-body 3.1 v-6, the car had no spark. It cranks just fine just no spark. Fuel pump primes. Had known good coil, icm, & pick up coil for dist, so I swapped them in. Still no spark. Added a ground to dist, made sure icm screws were clean, as well as dist body where icm sits. No spark still.
Car ran fine before dip stick R & R. The system uses the small dist with 8 pin icm and external coil.
Checked all wires going to ecm for continuity and short to ground. All was well. Swapped in 2 known good ecm's just in case. All engine and ecm grounds are good. All ecm and engine power wires are good.
When ign sw turned to run or start, coil gets battery power. Output to icm from coil gets battery power. C line from icm back to coil gets battery power. When cranking, voltage drops a little because of starter draw, but not enough to mess with ignition function.
Here's the problem. When car is cranked, dist shaft is turning, C control line from icm to coil does not go from power to no power. It stays lit. So icm is not turning on & off. And 3 other known good icm's are not turning oon & off either.
I'm not real familiar with the est aspect of the ign sys, but from what I've read in factory service manual, and online, this is a bypass system and icm should fire the coil without the est system working. Code 42 is proof. Dtc 42 is a problem with est. Code 42 troubleshooting starts with engine running, so est failure doesn't keep ign from creating spark.
I've swapped in an old 4 pin coil in cap dist, it sparks like up a storm, Turned it by hand and it worked. My icm will not turn on & off so coil will not spark.
Any ideas will be good. Anyone know what voltage or ohms readings the 4 est lines from icm to ecm should test as?
Car ran fine before dip stick R & R. The system uses the small dist with 8 pin icm and external coil.
Checked all wires going to ecm for continuity and short to ground. All was well. Swapped in 2 known good ecm's just in case. All engine and ecm grounds are good. All ecm and engine power wires are good.
When ign sw turned to run or start, coil gets battery power. Output to icm from coil gets battery power. C line from icm back to coil gets battery power. When cranking, voltage drops a little because of starter draw, but not enough to mess with ignition function.
Here's the problem. When car is cranked, dist shaft is turning, C control line from icm to coil does not go from power to no power. It stays lit. So icm is not turning on & off. And 3 other known good icm's are not turning oon & off either.
I'm not real familiar with the est aspect of the ign sys, but from what I've read in factory service manual, and online, this is a bypass system and icm should fire the coil without the est system working. Code 42 is proof. Dtc 42 is a problem with est. Code 42 troubleshooting starts with engine running, so est failure doesn't keep ign from creating spark.
I've swapped in an old 4 pin coil in cap dist, it sparks like up a storm, Turned it by hand and it worked. My icm will not turn on & off so coil will not spark.
Any ideas will be good. Anyone know what voltage or ohms readings the 4 est lines from icm to ecm should test as?