JasonH
This unit has been a pain in my rear for awhile now.  First, it was over speeding.  Another tech came in before me & screwed in the flywheel mag pickup all way in until the flywheel hit it.  That's when I got involved.  Replaced the pickup and set it, now the engine will not start.  The coils don't seem to be firing.  I have 9+VAC on wire 15D supplying voltage to the coils during starting, but it seems the ICM is not grounding the coils when appropriate.  I have checked all the other sensors & they test ok.  I have tried 2 other ICM boards and the same thing is happening.  

Anyone have any ideas???
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whiteturbo
What engine ? Did you use the harness to set the mag pickup or just screw it in and back it out ?
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JasonH
I used the breakout harness. Getting right at 3VAC.  It’s the Ford 4.2L engine.
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whiteturbo
Have no idea what it could be . Good Luck.
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cookelec
Wire 15D should supply 12VDC to the coils. You may want to check wire 15 which powers the ICM, wire 56 which applies 12VDC to the ICM during the start command and recheck 15D. They should be a 12VDC. This is based on the unit having an R200 controller.
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JasonH
I am seeing the battery voltage during starting.  I have 13.25VDC before the starting cycle, during starting, I see right at 10VDC at the battery, so there is a slight loss between the battery & 15D at this time.  I have spoke with another tech & he said this is normal.  Once the starting cycle is done, voltage will go back up.
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cookelec
Did you check wire 56 to the ICM. This is the start command to the module.
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JasonH
Yes.  But doesn't wire 56 come FROM the ICM to the starter contactor relay???  The engine is turning over, the coils are not firing.  Since all 6 coils are not firing, i'm leaning away from bad coils.
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cookelec
Wire 56 is energized during the start cycle and goes to the ICM to tell it to start and then the ICM latches in via 15. The ICM needs to be told a start command is issued and that is what 56 does.
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BrentB
It was many years ago, but I had a bad ICM, replaced it, still no fire. Touched base with tech, no doubt bad ICM. replaced again, still no fire. Called tech. again, still insisted bad ICM. ordered again. this one came in an oil filter box, with correct part # for ICM. It worked. Tech. said odds of that happening were so far out there I should buy a ticket for lotto! Moral of the story? just cause its brand new in the box, don't me its good. Does sound like it might be a ground issue rather than DCV issue?
Check wires 451,452,453,454,455,456(grounds for each coil) from the coils back to the plug on the ICM. Check wire zero in that plug pins 17 and 22 for continuity to ground.
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Peddler
I would check the run relay to make sure you are getting power to the #14 wire which powers the ICM in addition to the 15 wire.  This will only get power after the controller senses cranking by receiving the signal from the Mag pickup.  IF while cranking you have 12vdc at the #14 wire on the terminal strip, this would indicate this is OK. 
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JasonH
@Peddler: I have voltage on 14 & 15. 

@BrentB:  I previously performed a coil test at the ICM connector for the coils, checking resistance from Wire 15D through Wires 451, 452, 453, etc...  Have correct resistance.  Would this not rule out a wiring issue?  I also checked from each coil connector to ground to make sure there was no short, none detected. 
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Peddler
At this point the only thing you haven't said you have tested is the cam sensor and the crank sensor, wire 450 and 79a both of these are sensed by the ICM before it will fire.  On that engine the crank sensor is located behind the front pully.  I am not sure where the cam sensor is but I would guess you have a problem with one of those two.
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JasonH
Tested cam sensor, wire 450 through 0 - passed (541ohm) and crank sensor, wire 79A through 0 - passed (600ohm).  Both tested through the ICM connector.
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Peddler
I would check to see what VAC you get while cranking on these two sensors.
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JasonH
What should I see on them.  None of the documentation I have gives me voltage info, just resistance checks.  The only one with voltage is the flywheel sensor using the breakout harness, & I'm getting right at 3VAC on that.  What is the best way to test?  Back probe at the connectors from wire 450 and 79A to ground?
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Peddler
I don't know what the voltages should be but I would say you should see at least 1 volt cranking.  I will also say that 3 volts cranking is way high for the flywheel mag pick up, I usually shoot for 1 volt AC while cranking.  If you get no voltage on one or the other then I would think that would point toward a problem.
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JasonH
The diag. manual says 3VAC for 1800RPM engines and 5VAC for 3600RPM engines.

MP1.png
The cam sensor just reads a pulse as a magnet on the timing gear passes by.  Don't know what the crankshaft sensor reads.  Haven't found that info yet.
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Peddler
Those are the correct value with the engine running, as I understand the situation you have not been able to get the engine to start since you replaced the mag pick up.  I always shoot for 1 VSC while cranking, and this is usually fine.  Both the crank and the cam sensors should put out an AC voltage, though it may be small, just like the flywheel mag pickup will.  The presence of some voltage on the cam and crank sensor should rule them out as a cause.  Also on the back of most ICM's there is a brown phenolic plate which if you remove the plate you'll find there is a red LED.  It should glow solid if working correctly I think or flash a code for a fault of some type.
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JasonH
The original ICM flashed a Cam Sensor fault, but the sensor tested good, so I replaced ICM.  New ICM flashes no fault ( a single flash every .5 seconds ).  The flywheel sensor produces voltage because its sensing every tooth on the flywheel, so there is a constant.  The cam sensor only reads the magnet on timing gear, so it will only pulse.  Are you saying as long as I see some kind of change, the sensor is good?  
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BrentB
JasonH wrote:
Tested cam sensor, wire 450 through 0 - passed (541ohm) and crank sensor, wire 79A through 0 - passed (600ohm).  Both tested through the ICM connector.
      
RPM sensor is 0D2244M and should be 900-1000 ohms. Not sure about cam, different type.
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JasonH
BrentB wrote:
      
RPM sensor is 0D2244M and should be 900-1000 ohms. Not sure about cam, different type.


0D2244M is the flywheel sensor on wires 79 @ 0.  That tested at 987 ohms.  Its not the cam or crankshaft sensor.
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BrentB
Oh, you posted 600 ohms.
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JasonH
JasonH wrote:
Tested cam sensor, wire 450 through 0 - passed (541ohm) and crank sensor, wire 79A through 0 - passed (600ohm).  Both tested through the ICM connector.


BrentB wrote:
Oh, you posted 600 ohms.


The 600 ohms was on the Crank sensor on wires 79A through 0
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Peddler
I go back to your voltage on the mag pick up, if that is the cranking voltage it is too high.  Also you should see some voltage on the cam pulse and on the crank sensor during cranking.
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