ICM Test
Thread Starter
Intermediate
Joined: Aug 2007
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From: Oklahoma City OK
ICM Test
Is there a way to bench test the ICM?
1992 LT1 auto.
Secondary resistance on the coil is about 10,000 ohms. I realize thats out of range but is it too high, should I go ahead and replace the coil? Manual says the range should be 5,000 to 7,000 ohms.
1992 LT1 auto.
Secondary resistance on the coil is about 10,000 ohms. I realize thats out of range but is it too high, should I go ahead and replace the coil? Manual says the range should be 5,000 to 7,000 ohms.
Le Mans Master
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From: Life is just one big track event. Everything before and after is prep and warm-up and cool-down laps
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St. Jude Donor '12
Some of the auto parts places can check it, but they can't check it for working while hot.
Check for spark at the coil
Check for spark at the plugs
I just found out the opti rotor can dramatically fail without setting a code as well.
Burning Brakes
Joined: Feb 2009
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From: Richmond Virginia
Some of the auto parts places can check it, but they can't check it for working while hot.
I'd change the coil at least. Do some checks:
Check for spark at the coil
Check for spark at the plugs
I just found out the opti rotor can dramatically fail without setting a code as well.
If yours won't start at all, as stated above many parts stores can test the ICM. If you have a intermitant hot problem the ICM may test good but still cause a problem. Since you didn't say I'll assume you don't have a SES light.
Thread Starter
Intermediate
Joined: Aug 2007
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From: Oklahoma City OK
Had the ICM tested at Advanced Auto today. It was tested several times and got the green light but I was told that typically they are hot to the touch after testing. Mine stayed cold. Does that sound right?
Le Mans Master
Joined: Jan 2006
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From: Orlando FL
I would like to back up a bit and know what the original problem is. Could it be no spark?
I would start out checking the drive from the ECM and check for the 1.0 - 4.0 volts AC in pin "B" of the ICM connector. If that is good then you can proceed with checking the ICM and coil.
I have never had a ICM checked at a parts store. If they truly load the ICM then it should get hot. If it stays cool and checks good, you could be getting a false positive check.
I have always felt that substitution is the best test and check but that does not help your present problem. If they say it should get hot when it is tested, then that might be an indication it is defective
I would start out checking the drive from the ECM and check for the 1.0 - 4.0 volts AC in pin "B" of the ICM connector. If that is good then you can proceed with checking the ICM and coil.
I have never had a ICM checked at a parts store. If they truly load the ICM then it should get hot. If it stays cool and checks good, you could be getting a false positive check.
I have always felt that substitution is the best test and check but that does not help your present problem. If they say it should get hot when it is tested, then that might be an indication it is defective
Thread Starter
Intermediate
Joined: Aug 2007
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From: Oklahoma City OK
The main problem "right now" is no start, or should I say, no continue run. Fires right up, runs for a second then dies as if it's running out of gas. Fuel system however appears fine. Has and holds good pressure. Had similar problem years ago with this car and replaced the coil and that fixed it. Secondary resistance is way out of range on this coil. Just going thru process of elimination before I get the checkbook out. Checked the voltage, I've got 1.25 while cranking.
Le Mans Master
Joined: Jan 2006
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From: Orlando FL
Got an old good coil I measured. Primary is about 0.5 ohm and secondary measures 8.23K.
Hope this helps.
I have never looked in the FSM for this information. I don’t know where you got your numbers from, the FSM or another info book. I don’t know and have not researched if 10K is objectionable or not.
Hope this helps.
I have never looked in the FSM for this information. I don’t know where you got your numbers from, the FSM or another info book. I don’t know and have not researched if 10K is objectionable or not.
Last edited by pcolt94; May 27, 2011 at 10:55 AM.
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Le Mans Master
Joined: Mar 2001
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From: Life is just one big track event. Everything before and after is prep and warm-up and cool-down laps
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St. Jude Donor '12
Get thee a factory service manual - it will save a ton of time and parts swapping.
The troubleshooting flowcharts are great.
The Haynes is not so good.
The troubleshooting flowcharts are great.
The Haynes is not so good.
Le Mans Master
Joined: Jan 2006
Posts: 5,621
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From: Orlando FL
In reviewing the FSM for resistance measurements for the coil, I could not find it anywhere. They don’t seem to be concerned with furnishing that information, they may not feel that it is a valid piece of information. Aside from an open primary or secondary winding, an ohm meter is not a reliable way to check if a coil if is actually defective. You really need to check for shorted turns and the "Q" of the windings.
Aside from all that technical information, the ICMs break down much more than the coils do. The ICM is quick to replace although costs more than the coil. The coil is a bigger job to replace as you have to mount it in a bracket and possibly cut off some rivets.
Last edited by pcolt94; May 26, 2011 at 12:44 PM.
Le Mans Master
Joined: Jan 2006
Posts: 5,621
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From: Orlando FL
I would start off checking all connections and plugs. You have two unknowns in there now, coil and ICM. You can actually reconnect the original coil back in there by just connecting it and hanging it.
I would re-check any items you have already just to make sure of the status especially the injector pulses. Recheck the opti connections also.
Swapping the original ICM back in is quick and easy. You might need to go back to square one and make just one change at a time so you know what the effect is.
Le Mans Master
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From: Life is just one big track event. Everything before and after is prep and warm-up and cool-down laps
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St. Jude Donor '12
To bad you aren't close by.
I have to trouble shoot the race car and see if it needs something simple (coil, icm, ecm, opti) or a new engine - its my weekend big project
I have to trouble shoot the race car and see if it needs something simple (coil, icm, ecm, opti) or a new engine - its my weekend big project
Thread Starter
Intermediate
Joined: Aug 2007
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From: Oklahoma City OK
This things been plagued with these kinds of gremlins for a year now. Checked connections, all good. I'm gonna take the weekend off. Thanks everyone so far for your help, enjoy the Memorial Day weekend and we'll get back after it next week.
Thread Starter
Intermediate
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From: Oklahoma City OK
OK, After a couple days of testing everything and retesting everything with still no fire I resorted to putting the old coil and ICM back in. Guess what ?! It started.
So, let's move along. Why does the D#@n thing run for two seconds then die everytime. Fuel pressure is good and holds. Could the VATS crap be killing my injectors?
So, let's move along. Why does the D#@n thing run for two seconds then die everytime. Fuel pressure is good and holds. Could the VATS crap be killing my injectors?
Le Mans Master
Joined: Jan 2006
Posts: 5,621
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From: Orlando FL
You can move in one of two directional here, changing or checking.
Replace the coil and ICM one at a time. I would go for the coil first only because it can be unplugged and just hung in there, it's quick. If symptom is still the same I would them try the ICM. If it won't start, the new ICM might be bad.
But the way I personally would go first is make some tests in the current status before changing any parts. I would try to find out if I am loosing spark or the injector pulses. I would connect a noid light on a injector and a in line spark tester (or grounded plug) so when the engine quits, I then can try to start it and know exactly what I am missing.
I would also ask; after it dies, does it restart right away again, or is there is a wait period before it fires again?
Forget about classic VATS, you would not be able to crank it.
FEDS is part of what VATS activates to inhibit the injector drive. That why I want to see a noid light on there to see by some chance if you are losing injector drive. Something strange could be going on not letting the CCM communicate with the ECM turning on FEDS and letting the injector drive be activated. It is possible the ECM is related to no injector drive which are some known problems.
Just trying to find out what the actual problem area is.
Replace the coil and ICM one at a time. I would go for the coil first only because it can be unplugged and just hung in there, it's quick. If symptom is still the same I would them try the ICM. If it won't start, the new ICM might be bad.
But the way I personally would go first is make some tests in the current status before changing any parts. I would try to find out if I am loosing spark or the injector pulses. I would connect a noid light on a injector and a in line spark tester (or grounded plug) so when the engine quits, I then can try to start it and know exactly what I am missing.
I would also ask; after it dies, does it restart right away again, or is there is a wait period before it fires again?
Forget about classic VATS, you would not be able to crank it.
FEDS is part of what VATS activates to inhibit the injector drive. That why I want to see a noid light on there to see by some chance if you are losing injector drive. Something strange could be going on not letting the CCM communicate with the ECM turning on FEDS and letting the injector drive be activated. It is possible the ECM is related to no injector drive which are some known problems.
Just trying to find out what the actual problem area is.
Thread Starter
Intermediate
Joined: Aug 2007
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From: Oklahoma City OK
First, I must ground the starter enable relay with a jumper or nothing happens. It will start every time as fast as I can turn the key, no wait between starts. The noid light does stop flashing about a second after the car starts, then it runs for about another second and dies. Funny thing, if I pump the accelerator after it starts it will stay running - poorly - and only as long as I am working the peddle. The noid light also gets quite a bit brighter as the rpm's increase. When I stop pumping the peddle the light dies and so does the engine. It's got a good strong spark all the way till the engine stops turning.
Le Mans Master
Joined: Jan 2006
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From: Orlando FL
1) If you have a good spark, then why are you testing and changing the coil and ICM. If the spark is normal, then you need to get away from that area.
2) The way you now describe the problem is quite different. Are you saying that you can't crank the engine normally with the key but have to ground the relay. Then this starts to sound like a VATS problem. You need to find out firstly why you can't crank the car. It takes 3 minutes from a VATS event for the CCM to reset itself and time out. Every time you turn the key and it does not crank, it starts the clock again.
If it is VATS, then it would affect fuel delivery. The CCM has got to be happy and turn on the ECM to activate the injectors. Wipe the key pellet with alcohol to clean it or better try another key. You can actually clean the 2 contacts in the key cylinder for the key with a Q-tip. The wood ones work better because they are thinner and easy to get in.
If you really can't crank the car normally using the key than that might eliminate the ECM as a problem which is a good thing.
2) The way you now describe the problem is quite different. Are you saying that you can't crank the engine normally with the key but have to ground the relay. Then this starts to sound like a VATS problem. You need to find out firstly why you can't crank the car. It takes 3 minutes from a VATS event for the CCM to reset itself and time out. Every time you turn the key and it does not crank, it starts the clock again.
If it is VATS, then it would affect fuel delivery. The CCM has got to be happy and turn on the ECM to activate the injectors. Wipe the key pellet with alcohol to clean it or better try another key. You can actually clean the 2 contacts in the key cylinder for the key with a Q-tip. The wood ones work better because they are thinner and easy to get in.
If you really can't crank the car normally using the key than that might eliminate the ECM as a problem which is a good thing.