Do you have the right ICM? gray vs black ('93-'96)
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Fleet Mechanic
Joined: Mar 2009
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From: Sacramento Delta, CA
Do you have the right ICM? gray vs black ('93-'96)
Apparently around 1994, Ford introduced the black colored ICM which is computer controlled dwell. Until then Ford used the gray colored ICM which was "push start" dwell. ("Dwell" is defined below.*) The differences are discussed in the attached Ford Motor Company Diagnostic Systems Department Revised: March 13, 2002, which is excerpted below:
"2.3 - Push Start versus Computer Controlled Dwell TFI-IV ICMs
The internal circuitry of the TFI-IV ICM will have two possible arrangements; push start (PS) or computer controlled dwell (CCD).
The push start system allows for increased dwell (coil on time) when starting the engine. After engine start, the ICM internally determines coil on time (dwell) based on engine rpm (derived from the PIP signal), previous spark position and, coil charge time. The PCM calculates spark timing and outputs a rising edge of SPOUT at the appropriate time. The ICM turns the coil off whenever it sees a rising edge of SPOUT. The SPOUT signal is an acronym for SPark OUTput, a digital signal generated by the PCM. The falling edge of SPOUT is ignored by the ICM. On a push start system, SPOUT only controls when the coil fires. The dwell was designed to provide either 17% or 32% excess dwell to ensure sufficient coil charge time under transient engine-acceleration conditions. Push start TFI-IV ICMs are gray in color.
A computer controlled dwell (CCD) system uses both edges of the SPOUT signal. The PCM calculates spark timing and outputs a rising edge of SPOUT at the appropriate time. The ICM turns the coil off whenever it sees a rising edge of SPOUT. The falling edge of SPOUT is used by the ICM to turn the coil on. The coil on time (dwell), is therefore, entirely controlled by the PCM-generated SPOUT signal. The ICM does not internally determine dwell, it just responds to directly to SPOUT signal it receives. The PCM determined the correct dwell by measuring the time it takes for the coil to reach a predetermined current level. This has the advantage of limiting excess dwell, which significantly reduces heating in the ICM. TFI-IV ICMs that utilize computer-controlled dwell are black in color."
Using the wrong ICM in your truck will cause problems which are hard to identify.
One of the brothers on this forum whom I respect the most, just said this to me in a pm:
"1994 was the first year for the Computer Controlled Dwell style ignition on these trucks. This requires the black colored ICM to work properly.
Even the Ford documentation is usually wrong for the replacement part number."
Do you have the right ICM in your truck? I have an 1995 Bronco 5.8L and it has a gray color ICM. Should it have the black colored ICM?
[Edit: FYI, as discussed later in this thread, I was wrong, once I cleaned it up, my 1995 Bronco's ICM was, in fact, black which was correct. The particular problem I was chasing was a weakening then failed PIP signal caused by a weakening and then failed Hall Effect generator in the distributor, which a new distributor with the correct distributor gear cured.]
The attached following Ford Motor Company report describes how the two different colored ICM's operate differently but does not tell you how to identify which colored ICM you should have. And apparently there is some confusion with even Ford techs on this issue during the transition years '93-'96.
http://r.duckduckgo.com/l/?kh=-1&udd...n-tfi-edit.doc
See the attached Word document version of the above link.
Also see:
Reference: - Identifying and Understanding Ford Ignition Systems | FordForumsOnline.com
SO BY LOOKING AT THE TRUCK WIRING OR BY TESTING THE PINOUTS (NOT BY VIN#) DOES ANYONE KNOW HOW TO IDENTIFY WHICH COLORED ICM A 1993-1996 TRUCK SHOULD HAVE?
* "Q: What Is Dwell? (Electronic Ignition Engines)
A: Dwell is the amount of time required to charge an inductive coil to its maximum energy level. In terms of modern engine control, dwell is defined in milliseconds. Typical ID coils will have a dwell between 2ms and 5ms. Electronic ignition is much better at regulating dwell than distributor based engines."
https://spdispark.com/pages/frequent...s-dwell.html#Q: What Is Dwell? (Distributor Ignition Engines)
"2.3 - Push Start versus Computer Controlled Dwell TFI-IV ICMs
The internal circuitry of the TFI-IV ICM will have two possible arrangements; push start (PS) or computer controlled dwell (CCD).
The push start system allows for increased dwell (coil on time) when starting the engine. After engine start, the ICM internally determines coil on time (dwell) based on engine rpm (derived from the PIP signal), previous spark position and, coil charge time. The PCM calculates spark timing and outputs a rising edge of SPOUT at the appropriate time. The ICM turns the coil off whenever it sees a rising edge of SPOUT. The SPOUT signal is an acronym for SPark OUTput, a digital signal generated by the PCM. The falling edge of SPOUT is ignored by the ICM. On a push start system, SPOUT only controls when the coil fires. The dwell was designed to provide either 17% or 32% excess dwell to ensure sufficient coil charge time under transient engine-acceleration conditions. Push start TFI-IV ICMs are gray in color.
A computer controlled dwell (CCD) system uses both edges of the SPOUT signal. The PCM calculates spark timing and outputs a rising edge of SPOUT at the appropriate time. The ICM turns the coil off whenever it sees a rising edge of SPOUT. The falling edge of SPOUT is used by the ICM to turn the coil on. The coil on time (dwell), is therefore, entirely controlled by the PCM-generated SPOUT signal. The ICM does not internally determine dwell, it just responds to directly to SPOUT signal it receives. The PCM determined the correct dwell by measuring the time it takes for the coil to reach a predetermined current level. This has the advantage of limiting excess dwell, which significantly reduces heating in the ICM. TFI-IV ICMs that utilize computer-controlled dwell are black in color."
Using the wrong ICM in your truck will cause problems which are hard to identify.
One of the brothers on this forum whom I respect the most, just said this to me in a pm:
"1994 was the first year for the Computer Controlled Dwell style ignition on these trucks. This requires the black colored ICM to work properly.
Even the Ford documentation is usually wrong for the replacement part number."
Do you have the right ICM in your truck? I have an 1995 Bronco 5.8L and it has a gray color ICM. Should it have the black colored ICM?
[Edit: FYI, as discussed later in this thread, I was wrong, once I cleaned it up, my 1995 Bronco's ICM was, in fact, black which was correct. The particular problem I was chasing was a weakening then failed PIP signal caused by a weakening and then failed Hall Effect generator in the distributor, which a new distributor with the correct distributor gear cured.]
The attached following Ford Motor Company report describes how the two different colored ICM's operate differently but does not tell you how to identify which colored ICM you should have. And apparently there is some confusion with even Ford techs on this issue during the transition years '93-'96.
http://r.duckduckgo.com/l/?kh=-1&udd...n-tfi-edit.doc
See the attached Word document version of the above link.
Also see:
Reference: - Identifying and Understanding Ford Ignition Systems | FordForumsOnline.com
SO BY LOOKING AT THE TRUCK WIRING OR BY TESTING THE PINOUTS (NOT BY VIN#) DOES ANYONE KNOW HOW TO IDENTIFY WHICH COLORED ICM A 1993-1996 TRUCK SHOULD HAVE?
* "Q: What Is Dwell? (Electronic Ignition Engines)
A: Dwell is the amount of time required to charge an inductive coil to its maximum energy level. In terms of modern engine control, dwell is defined in milliseconds. Typical ID coils will have a dwell between 2ms and 5ms. Electronic ignition is much better at regulating dwell than distributor based engines."
https://spdispark.com/pages/frequent...s-dwell.html#Q: What Is Dwell? (Distributor Ignition Engines)
Fleet Owner
Joined: Oct 2005
Posts: 20,761
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From: Kentucky
1993 and earlier trucks use the gray colored Push-Start style Ignition Control Module. There are two different versions.
One is distributor mounted
Motorcraft - DY1074 (supercedes DY425)
Ford - 5U2J-12A297-AA, 5U2Z-12A297-A
Wells - F121
Niehoff - FF409
BWD - CBE24
Standard - LX218
NapaEchlin - TP31
Delphi - DS10051
Transpo - FM425
MSD - 83648 (Made by Transpo above)
The other is a remote mount Push-Start ICM
Motorcraft - DY1075 (supercedes DY533)
Ford - 5U2Z12A297B (supercedes E
Z-12A297-A)Wells - F125
Niehoff - FF411
BWD - CBE33
Standard - LX226
NapaEchlin - TP33
Delphi - DS10053
Transpo - FM533
1994 and later trucks use a remote mount CCD-style ICM
Motorcraft - DY1077 (supercedes DY679, DY667, DY645)
Ford - 5U2Z-12A297-D (supercedes F1PZ-12A297-A)
Wells - F139
Niehoff - FF413
BWD - CBE40
Standard - LX-241
NapaEchlin - TP29
Delphi - DS10056
Transpo - FM544
This is discussed at length on this forum pretty much every week. Ford's documentation for the most part have the part numbers/descriptions reversed for the actual application. The aftermarket copied their info so most have the same issue. The above is correct and has been verified dozens of times.
Fleet Owner
Joined: Oct 2005
Posts: 20,761
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From: Kentucky
Thanks for the vote of confidence. We are blessed with a collective knowledge base on this site/forum. I started here with basic skills and honed them by reading and absorbing.
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Fleet Mechanic
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From: Sacramento Delta, CA
Fordbronco1995: Would you post up whether you have a 49-state or a California-only emissions vehicle? And if you can get it off your door sticker, the date of manufacturer?
Here is what one person said about the gray ICM on Amazon:
"By Joel A. on July 18, 2016
This would have been fine, though it has no motorcraft ensignia it did have ford box and p/n. But I believe all parts books are wrong including Amazon's. I need the black CCD ignition control module. Remember, if you have a 94 forward, you need a black one, no matter what anyone tells you. The grey one works (where a black one should be) just well enough to drive you crazy."
Here is what one person said about the gray ICM on Amazon:
"By Joel A. on July 18, 2016
This would have been fine, though it has no motorcraft ensignia it did have ford box and p/n. But I believe all parts books are wrong including Amazon's. I need the black CCD ignition control module. Remember, if you have a 94 forward, you need a black one, no matter what anyone tells you. The grey one works (where a black one should be) just well enough to drive you crazy."
Cargo Master
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Fleet Mechanic
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From: Sacramento Delta, CA
wtroger: I will pull KOEO codes tomorrow. I can't pull KOER codes because it won't start. This is what tmoss says:
"If in doubt about which TFI module belongs on a particular vehicle, consult the ignition system-wiring diagram for the vehicle. If the wire going to pin #4 on the EEC-IV computer comes directly from pin #4 of the TFI module, it is a CCD system. If not, it is a Push Start system."
https://www.stangnet.com/mustang-for...module.765890/
So, I will also check the wiring.
"If in doubt about which TFI module belongs on a particular vehicle, consult the ignition system-wiring diagram for the vehicle. If the wire going to pin #4 on the EEC-IV computer comes directly from pin #4 of the TFI module, it is a CCD system. If not, it is a Push Start system."
https://www.stangnet.com/mustang-for...module.765890/
So, I will also check the wiring.
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Fleet Mechanic
Joined: Mar 2009
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From: Sacramento Delta, CA
wtroger: I will pull KOEO codes tomorrow. I can't pull KOER codes because it won't start. This is what tmoss says:
"If in doubt about which TFI module belongs on a particular vehicle, consult the ignition system-wiring diagram for the vehicle. If the wire going to pin #4 on the EEC-IV computer comes directly from pin #4 of the TFI module, it is a CCD system. If not, it is a Push Start system."
https://www.stangnet.com/mustang-for...module.765890/
So, I will also check the wiring.
"If in doubt about which TFI module belongs on a particular vehicle, consult the ignition system-wiring diagram for the vehicle. If the wire going to pin #4 on the EEC-IV computer comes directly from pin #4 of the TFI module, it is a CCD system. If not, it is a Push Start system."
https://www.stangnet.com/mustang-for...module.765890/
So, I will also check the wiring.
Fleet Owner
Joined: Aug 2005
Posts: 23,666
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From: Easton,Ks
As noted above just check you Trucks VIN and if it is a 1994 Truck or newer it takes a Black ICM.
KOEO will only give a code for the wrong ICM if the codes have not been cleared and then it will only be in the CM stored codes after the KOEO electrical part of the code is done and you get a space code.
Note some cars (not trucks) used the CCD Black ICM before 1994.
KOEO will only give a code for the wrong ICM if the codes have not been cleared and then it will only be in the CM stored codes after the KOEO electrical part of the code is done and you get a space code.
Note some cars (not trucks) used the CCD Black ICM before 1994.
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Fleet Mechanic
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From: Sacramento Delta, CA
subford: Thanks for posting! So, I have a gray ICM and a crank no start condition except when Abraham's RadioShack test lamp is used, when, incredibly, the engine starts! See: https://www.ford-trucks.com/forums/1...51-eec-iv.html So do I replace the gray ICM with a black ICM and see if my distributor is ok? I think that is what I will do...
But back to the gray vs black ICM confusion. The plot thickens...
My Ford 1995 Bronco Electrical And Vacuum Troubleshooting Manual which has a June 1994 publication date, says "GRAY" on the picture below the ICM on page 21-2. (See attached.)
But my Ignition System schematic on page 21-1 (also attached) shows that the IDM wire goes directly from pinout #3 on the ICM to pinout #4 on the PCM. (I will verify that by looking at the actual wiring this evening after work.) So, if tmoss is correct in the article which I linked in post #9 above, then what you and rla2005 and FordBronco1995 are saying is likely correct, since my Bronco is, in fact, a 1995 with a build date of 6/95 from the driver's side door jamb sticker, then somebody must have replaced the original black ICM with a gray one and I need to install a black ICM?
But back to the gray vs black ICM confusion. The plot thickens...
My Ford 1995 Bronco Electrical And Vacuum Troubleshooting Manual which has a June 1994 publication date, says "GRAY" on the picture below the ICM on page 21-2. (See attached.)
But my Ignition System schematic on page 21-1 (also attached) shows that the IDM wire goes directly from pinout #3 on the ICM to pinout #4 on the PCM. (I will verify that by looking at the actual wiring this evening after work.) So, if tmoss is correct in the article which I linked in post #9 above, then what you and rla2005 and FordBronco1995 are saying is likely correct, since my Bronco is, in fact, a 1995 with a build date of 6/95 from the driver's side door jamb sticker, then somebody must have replaced the original black ICM with a gray one and I need to install a black ICM?
Fleet Owner
Joined: Oct 2005
Posts: 20,761
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From: Kentucky
Your attachment and observations are just like everyone has stated. Even Ford's documentation is wrong. A 1995 model year gas engine truck needs a black colored CCD-style Ignition Control Module.
For your issue the gray colored ICM is not the cause of your no start condition, unless itself is bad. The truck will run with it, but not as it was designed.
For your issue the gray colored ICM is not the cause of your no start condition, unless itself is bad. The truck will run with it, but not as it was designed.
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Fleet Mechanic
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From: Sacramento Delta, CA
10-4 rla2005 I am waiting for pricing for both the black ICM based on the PN you provided (again thank you) and for the distributor (which unless you also have recommended PN for that) I have asked my parts lady to track via VIN#.
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Fleet Mechanic
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From: Sacramento Delta, CA
subford: Here's my Calibration sticker. I am going to continue this over at my crank no start thread:
https://www.ford-trucks.com/forums/1...l#post17089140
Because based of what rla2005 says above and also what my easyautodiagnostics.com troubleshooting indicates I think it is time to throw some money at replacing my distributor. Later I will revisit this thread when I buy an ICM.
https://www.ford-trucks.com/forums/1...l#post17089140
Because based of what rla2005 says above and also what my easyautodiagnostics.com troubleshooting indicates I think it is time to throw some money at replacing my distributor. Later I will revisit this thread when I buy an ICM.