What do you do when you get codes 41 and 72?
Thread Starter
Instructor
Joined: Mar 2004
Posts: 116
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From: Knee deep in Amish PA
What do you do when you get codes 41 and 72?
OK gurus, my mechanic isn't getting anywhere, and I need a problem dealt with! I have been having a no start issue lately. It seems to happen after I have been driving it for a while, and I stop for just 10 minutes. If the car is hot, over 200, and I stop at a gas station for a drink, when I come out the car will not start. It turns over but will not fire. The ASR service light comes on, and the SYS and security lights flash. After about 5-10 minutes, the car will start and will run fine. If I stop for a longer period, like 20 minutes or more, it will not happen. If the car is not hot, it will not happen. It seems like the combination of heat and a short stop. I made it happen at the shop, and we tested for spark. No spark. We were also going to test for a fuel injector pulse, but by that time the car was starting on its own.
Tonight, I pulled CCM codes, and got H41 (ECM data communication lost) in module 1, and H72 (serial data link error) in module 9. I also getting C12 code on module 1, but not modules 4 and 9 after clearing the codes.
So, does anyone have an idea? Bad ground? Bad wire? I'm excited that the car is almost there, but I would like to resolve this one because it annoys me. That and the AC not working. July looks to be a hot one! Thanks in advance! Jon
Tonight, I pulled CCM codes, and got H41 (ECM data communication lost) in module 1, and H72 (serial data link error) in module 9. I also getting C12 code on module 1, but not modules 4 and 9 after clearing the codes.
So, does anyone have an idea? Bad ground? Bad wire? I'm excited that the car is almost there, but I would like to resolve this one because it annoys me. That and the AC not working. July looks to be a hot one! Thanks in advance! Jon
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Joined: Jul 2010
Posts: 59
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From: Bolingbrook IL
You can read through this http://www.corvettephotographs.com/c4vettes/ecm.htm
The chart at the bottom gives some probable causes.
The chart at the bottom gives some probable causes.
Le Mans Master
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
Start praying 
As you can see from the links below; may be as simple as a bad ground or something far more complex and time consuming to identify
http://forums.corvetteforum.com/1554492041-post15.html
http://forums.corvetteforum.com/c4-s...cm-or-ccm.html
http://www.digitalcorvettes.com/foru...5&postcount=17
http://forums.corvetteforum.com/c4-t...wes-is-me.html
As you can see from the links below; may be as simple as a bad ground or something far more complex and time consuming to identify
http://forums.corvetteforum.com/1554492041-post15.html
http://forums.corvetteforum.com/c4-s...cm-or-ccm.html
http://www.digitalcorvettes.com/foru...5&postcount=17
http://forums.corvetteforum.com/c4-t...wes-is-me.html
Advanced
Joined: Jul 2010
Posts: 59
Likes: 0
From: Bolingbrook IL
I fixed my code 41 and 72 problems!
According to the Factory Service Manual Code 41 could be three things: ECM related, a short/ bad connection in the wiring, or the Ignition Control Module/Coil.
Mine is well cared for so the wiring issue was doubtful. The ECM is really expensive- if you can find one - so i went with the ICM/Coil.
The coil was $24, and the ICM was $102 at the local parts store. Not cheap for that little module but it's back up and running strong again.
The 72 code is for a shifter fault (the ECM can't tell what gear it's in.) I found the cable bracket bolted to the trans pan was loose and wobbling. Just tightened the bolts - fixed - free!
Rick - '92 LT1
According to the Factory Service Manual Code 41 could be three things: ECM related, a short/ bad connection in the wiring, or the Ignition Control Module/Coil.
Mine is well cared for so the wiring issue was doubtful. The ECM is really expensive- if you can find one - so i went with the ICM/Coil.
The coil was $24, and the ICM was $102 at the local parts store. Not cheap for that little module but it's back up and running strong again.
The 72 code is for a shifter fault (the ECM can't tell what gear it's in.) I found the cable bracket bolted to the trans pan was loose and wobbling. Just tightened the bolts - fixed - free!
Rick - '92 LT1
Le Mans Master
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
