Snoop dogg
Saturday Night Special
It's a 1987 2wd 4.3 truck, auto.
But everything I've seen under the hood looks like the 88-93 ignition system.
Icm inside distributor cap. 4 prong plug and 2 prong plug on icm, with 2 wire pickup coil going to it.
No spark, no fuel, but cranks. I believe that eliminates it being a neutral safety switch.
The no fuel and no spark leads me to believe ICM OR/AND ECM.
I have a couple icms, and apparently no parts house tests them anymore...at least not the places I frequent. (So they could all be bad for all I know) I bought a new coil to have as a control. (Ac Delco but I know it could be bad out the box)
I've swapped in a new coil and old coil, older icm, and older icm relay . All one by one till it was all swapped over. Still no spark and no fuel.
It's my understanding that the icm can control spark AND fuel?
Am I incorrect in that thought?
And then ECM takes over and controls timing and fuel?
What I have left is to jump 12v to pick up coil on distributor and test coil for spark. If there's spark than the pickup coil has gone bad, correct?
How I was thinking about doing this was jumper wire from pos. Battery post to one of the coil pick up wires....crank over motor and see if the ignition coil sparks to my screwdriver. Should that work?
Trying to understand how the distributor and icm interact to signal fuel and spark.
I *think (lol). I'm narrowing it down to bad pickup coil or bad ECM. Not toooo much grey matter in my dome, and the Chilton's book is ok for help but doesn't really elaborate on troubleshooting. I have not spent the money on a new icm and would like to figure out the root of the issue before I by another part bc it seems like it's either gonna be a new distributor , new ECM, or new icm.
Ive only found the relay for the icm that is on the intake manifold, is there any other relay on that circuit? I Have voltage for the ign and ECM fuses at the fuse block , drops a little when cranking. Maybe ign. Switch?
Thanks!
But everything I've seen under the hood looks like the 88-93 ignition system.
Icm inside distributor cap. 4 prong plug and 2 prong plug on icm, with 2 wire pickup coil going to it.
No spark, no fuel, but cranks. I believe that eliminates it being a neutral safety switch.
The no fuel and no spark leads me to believe ICM OR/AND ECM.
I have a couple icms, and apparently no parts house tests them anymore...at least not the places I frequent. (So they could all be bad for all I know) I bought a new coil to have as a control. (Ac Delco but I know it could be bad out the box)
I've swapped in a new coil and old coil, older icm, and older icm relay . All one by one till it was all swapped over. Still no spark and no fuel.
It's my understanding that the icm can control spark AND fuel?
Am I incorrect in that thought?
And then ECM takes over and controls timing and fuel?
What I have left is to jump 12v to pick up coil on distributor and test coil for spark. If there's spark than the pickup coil has gone bad, correct?
How I was thinking about doing this was jumper wire from pos. Battery post to one of the coil pick up wires....crank over motor and see if the ignition coil sparks to my screwdriver. Should that work?
Trying to understand how the distributor and icm interact to signal fuel and spark.
I *think (lol). I'm narrowing it down to bad pickup coil or bad ECM. Not toooo much grey matter in my dome, and the Chilton's book is ok for help but doesn't really elaborate on troubleshooting. I have not spent the money on a new icm and would like to figure out the root of the issue before I by another part bc it seems like it's either gonna be a new distributor , new ECM, or new icm.
Ive only found the relay for the icm that is on the intake manifold, is there any other relay on that circuit? I Have voltage for the ign and ECM fuses at the fuse block , drops a little when cranking. Maybe ign. Switch?
Thanks!