No start LT1 help - 0 volts to ICM connector shbox test
07-27-2012, 01:01 PM
#1
No start LT1 help - 0 volts to ICM connector shbox test Having an issue with my 383 
The car will crank but not start. Fuel pressure is good.
I was thinking maybe my brand new MSD coil went bad so I've switched between an OEM coil and the MSD and no help. So I've been using shbox's site, specifically:
http://shbox.com/1/4th_gen_tech2.html#opti_test
Disconnect the ICM connector. Leave coil connected (important).
Check for dc voltage with a digital meter at harness terminal "A" to ground and and also "D" to ground
I get 0 (or near 0) volts with both of the A and D connectors.
Result should be 10v dc or more on the A and D terminals. If you get no voltage, use the diagram and chase back toward the coil and the ignition fuse. Power for the ICM comes from the ignition fuse and through the coil, so any of that could be bad.
I disconnected the ignition fuse and checked continuity from the ICM connector to the ignition fuse and I get continuity (specifically like 1 ohm lol). What gives not sure what to do next :/
The same results happen with either coil. Oh and the three grounds are hooked up...
The car will crank but not start. Fuel pressure is good.I was thinking maybe my brand new MSD coil went bad so I've switched between an OEM coil and the MSD and no help. So I've been using shbox's site, specifically:
http://shbox.com/1/4th_gen_tech2.html#opti_test
Disconnect the ICM connector. Leave coil connected (important).
Check for dc voltage with a digital meter at harness terminal "A" to ground and and also "D" to ground
I get 0 (or near 0) volts with both of the A and D connectors.
Result should be 10v dc or more on the A and D terminals. If you get no voltage, use the diagram and chase back toward the coil and the ignition fuse. Power for the ICM comes from the ignition fuse and through the coil, so any of that could be bad.
I disconnected the ignition fuse and checked continuity from the ICM connector to the ignition fuse and I get continuity (specifically like 1 ohm lol). What gives not sure what to do next :/
The same results happen with either coil. Oh and the three grounds are hooked up...
12-12-2012, 06:59 PM
#7
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having the exact same issue here, wondering if you found a fix
edit---
not the coil either, no power there as well, tried 3 opti's none are the culprit, 2 ICM (both good) and 2 coils (both good)
aside from chasing spark through the harness is there a simple problem I am overlooking here?
car started and ran beautifully for a brief moment when seeing if the replacement opti was good (original reason for working on it) buttoned everything back up and went to start... had no spark and spent a good portion of today trying to figure out why (as well as throwing the usually suspected parts at the problem)
All to no avail. terminals A and D on the ICM get no power, coil gets no power, IGN fuse has 12V.
edit---
not the coil either, no power there as well, tried 3 opti's none are the culprit, 2 ICM (both good) and 2 coils (both good)
aside from chasing spark through the harness is there a simple problem I am overlooking here?
car started and ran beautifully for a brief moment when seeing if the replacement opti was good (original reason for working on it) buttoned everything back up and went to start... had no spark and spent a good portion of today trying to figure out why (as well as throwing the usually suspected parts at the problem)
All to no avail. terminals A and D on the ICM get no power, coil gets no power, IGN fuse has 12V.
Last edited by lt1slowz28; 12-12-2012 at 07:22 PM.
