My ICM is sending a weak spark signal | Ford Explorer Forums - Serious Explorations

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My ICM is sending a weak spark signal

1993Saturn

Well-Known Member
Joined
November 21, 2008
Messages
160
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City, State
Redmond, OR
Year, Model & Trim Level
94 4x4
93, 99 Bauer 4x4
I've somehow managed to end up with 2 strong spark signals being sent from the ICM (tested at the ICM) and one really weak signal for Coil #1. I use an LED tester and the light for the weak signal barely shows. As a result, Coil #1 sends out a really tiny spark, not enough to fire it's 2 plugs. What's the problem?
 






Coil pack?
 






I really can't speak to your LED method. If one signal to the coil pack is lower than the other two, it could be low output from the ICM or a short in the coil pack. There are ohmmeter tests on-line for the coil pack... I suppose I would do that to rule it out. I've been sitting here trying to decide if a plug wire that was arcing to ground could cause this... my transformer theory is a little dated, but if a wire were gounding, it would reduce the peak secondary voltage, which would reduce the primary voltage. I might look at the wires since you are going to be right there anyway.

Ohm test the coil pack, inspect the plug wires, and if all that were good, I'd try a new/salvage ICM.
 






The ICM rarely fails, my bet is on the coil pack.
 






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