ECM or CCM
Thread Starter
Instructor
Joined: Jun 2006
Posts: 195
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From: Canyon Country CA
ECM or CCM
Over the past few weeks, the security and sys lights have occasionally flashed on my 93. The service ASR light also comes on. It hasn't made a perceptable difference when it occured while already running. A couple of times I have had to wait a few min to get started. The codes I've pulled are
1. H41 & H54
4. H27
9. H72
If my car won't start, I can opened my hood, and smack the ECM with the heel/palm of my hand. The car starts and runs perfectly. I assumed this was pretty good evidence that my ECM is bad. As many of you know the ECMs are currently damn hard to find.
After reading many of the CF posts, I'm not sure if it's the ECM.
Does my smack of the ECM prove it's bad or am I just "rebooting" for lack of a better term.
I have the factory manuals but the H41 looks to require a special tool to troubleshoot.
(I'm hoping to get bogus to weigh in on this)
Thanks in advance for all of your great replies!
Joe
1. H41 & H54
4. H27
9. H72
If my car won't start, I can opened my hood, and smack the ECM with the heel/palm of my hand. The car starts and runs perfectly. I assumed this was pretty good evidence that my ECM is bad. As many of you know the ECMs are currently damn hard to find.
After reading many of the CF posts, I'm not sure if it's the ECM.
Does my smack of the ECM prove it's bad or am I just "rebooting" for lack of a better term.
I have the factory manuals but the H41 looks to require a special tool to troubleshoot.
(I'm hoping to get bogus to weigh in on this)
Thanks in advance for all of your great replies!
Joe
Le Mans Master
Joined: Jan 2006
Posts: 6,564
Likes: 6
From: Woodstock Georgia
I am not Andy Bogus, but Andy in Georgia. So here is a thought--smacking an ECM with the palm of your hand might make you feel better, but I doubt the ECM really cares much. However, it might indicate a bad connection at the harness(s) or ground. Like I said, just a thought.
Thread Starter
Instructor
Joined: Jun 2006
Posts: 195
Likes: 0
From: Canyon Country CA
Andy,
Thanks for the reply, it was not my intention to exclude anyone by mentioning bogus in my original post. I'm pretty new to these cars and feel fortunate to have CF as a resource. I just want to get this corrected without swaping a bunch of expensive electronics uneccessarily. It seems from reading the many posts about ECM & CCM, this is not an original problem. I hope someone has experienced and resolved the same problem.
When the car will crank but not start, the handshake required to turn the injectors on is not happening. The smack seems to correct this.
Joe
Thanks for the reply, it was not my intention to exclude anyone by mentioning bogus in my original post. I'm pretty new to these cars and feel fortunate to have CF as a resource. I just want to get this corrected without swaping a bunch of expensive electronics uneccessarily. It seems from reading the many posts about ECM & CCM, this is not an original problem. I hope someone has experienced and resolved the same problem.
When the car will crank but not start, the handshake required to turn the injectors on is not happening. The smack seems to correct this.
Joe
Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
an H41 indicates a comm problem between the ECM and the CCM.
Now, for the rub... I don't know where it is!
There are redundant, parallel wires that run from the ECM to the CCM - if the H41 code is present, it means that the data connection has been effected. I am guessing that the UART in the ECM is failing. I would take the harness from the CCM off and the harness of the ECM and test the connection for the Serial Data Line.
On the CCM, it's circuit 800, ports E13 and F12, the wire is TAN in colour. This info is from my 1992 Helm Manual, but 1993 is VERY similar.
Test the continuity. That's my first suggestion.
I doubt the CCM is bad... but the SDL is needed to handshake the VATS data to the ECM to allow the engine to start. If the ECM can't recieve this data, then the engine won't start.
H27? I don't see that.
H72 means that the EBCM isn't getting any data.
The EBCM needs RPM info to feed the ASR.
Now, for the rub... I don't know where it is!
There are redundant, parallel wires that run from the ECM to the CCM - if the H41 code is present, it means that the data connection has been effected. I am guessing that the UART in the ECM is failing. I would take the harness from the CCM off and the harness of the ECM and test the connection for the Serial Data Line.
On the CCM, it's circuit 800, ports E13 and F12, the wire is TAN in colour. This info is from my 1992 Helm Manual, but 1993 is VERY similar.
Test the continuity. That's my first suggestion.
I doubt the CCM is bad... but the SDL is needed to handshake the VATS data to the ECM to allow the engine to start. If the ECM can't recieve this data, then the engine won't start.
H27? I don't see that.
H72 means that the EBCM isn't getting any data.
The EBCM needs RPM info to feed the ASR.
Advanced
Joined: Sep 2005
Posts: 97
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From: Stockholm / Sweden
Originally Posted by ccford
As many of you know the ECMs are currently damn hard to find.
Thanks in advance for all of your great replies!
Joe
Thanks in advance for all of your great replies!
Joe
http://cgi.ebay.com/ebaymotors/REBUI...spagenameZWDVW
I bet for the ECM, I had the same problem and changed the ECM and the problem was solved. But be sure to check all grounding also before getting a new ECM.
Regards
MickeW
Instructor
Joined: Jul 2004
Posts: 210
Likes: 0
From: Lakewood CO
I've been looking for another ECM and saw that Ebay add when it was listed prevously. I emailed the guy to ask him if it was ever tested in a car and his only reply was "yes tested my company rebuilted the ecm call me at xxx-xxx-xxxx. Do you have an old ecm?"
I thought that was strange and didn't want to trust a computer rebuild to someone who doesn't know that rebuilt is plural and rebuilted isn't a word.
Dave
I thought that was strange and didn't want to trust a computer rebuild to someone who doesn't know that rebuilt is plural and rebuilted isn't a word.
Dave
Thread Starter
Instructor
Joined: Jun 2006
Posts: 195
Likes: 0
From: Canyon Country CA
Originally Posted by bogus
I doubt the CCM is bad... but the SDL is needed to handshake the VATS data to the ECM to allow the engine to start. If the ECM can't recieve this data, then the engine won't start.
H27? I don't see that.
H27? I don't see that.
H27 is "LCD Blanking Control Circuit Open or Shorted to Ground" per my 93 factory manual
Tx
Joe
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Joined: May 2006
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From: Pittsburgh PA
Originally Posted by L71Maynard
I've been looking for another ECM and saw that Ebay add when it was listed prevously. I emailed the guy to ask him if it was ever tested in a car and his only reply was "yes tested my company rebuilted the ecm call me at xxx-xxx-xxxx. Do you have an old ecm?"
I thought that was strange and didn't want to trust a computer rebuild to someone who doesn't know that rebuilt is plural and rebuilted isn't a word.
Dave
I thought that was strange and didn't want to trust a computer rebuild to someone who doesn't know that rebuilt is plural and rebuilted isn't a word.
Dave
Pricy but have you looked at one of these? www.fuelairspark.com
