ccm nightmare
Thread Starter
6th Gear
Joined: Jul 2011
Posts: 6
Likes: 0
ccm nightmare
My 90 vette convertible ccm is giving me codes c41 and h41. How much would it cost to bypass the ccm. The car sat for five years and a mouse did a job on the inside dashboard. I had it running when I first started working on it but ran terrible so. Now it doesn't run at all. It cranks but the fuel pump fuse circuit is shut down and the injectors aren't pulsing. If you spray starter fluid it purrs fine. I replaced tps, map sensor, ECM , ignition module, ignition switch, fuel pump and I have a vats bypass chip adapter made from PCM for less so security is not the problem.
The cooling fan were also working until right before the car died and relays are good. I also replaced the fuel pump and injector relays.
I do not want to carb this car out because i know i wil have tranny issues later and some newer problem i think. i am in the process of trying to remove the ccm and test the ecm data wire but what a freaking nightmare!!!! any help would be appreciated...
The cooling fan were also working until right before the car died and relays are good. I also replaced the fuel pump and injector relays.
I do not want to carb this car out because i know i wil have tranny issues later and some newer problem i think. i am in the process of trying to remove the ccm and test the ecm data wire but what a freaking nightmare!!!! any help would be appreciated...
Drifting
Joined: Jun 2010
Posts: 1,853
Likes: 8
From: Westerly RI
The CCM is integral to many circuits and functions. It is not practical to do away with it. Even if you could, this would not likely solve your chewed wiring issues. There is a LOT of wiring behind the dash, you will need a good diagram and some patience to sort it out.
Supporting Vendor
Joined: Mar 2008
Posts: 1,762
Likes: 14
From: Cumming Ga
My 90 vette convertible ccm is giving me codes c41 and h41. How much would it cost to bypass the ccm. The car sat for five years and a mouse did a job on the inside dashboard. I had it running when I first started working on it but ran terrible so. Now it doesn't run at all. It cranks but the fuel pump fuse circuit is shut down and the injectors aren't pulsing. If you spray starter fluid it purrs fine. I replaced tps, map sensor, ECM , ignition module, ignition switch, fuel pump and I have a vats bypass chip adapter made from PCM for less so security is not the problem.
The cooling fan were also working until right before the car died and relays are good. I also replaced the fuel pump and injector relays.
I do not want to carb this car out because i know i wil have tranny issues later and some newer problem i think. i am in the process of trying to remove the ccm and test the ecm data wire but what a freaking nightmare!!!! any help would be appreciated...
The cooling fan were also working until right before the car died and relays are good. I also replaced the fuel pump and injector relays.
I do not want to carb this car out because i know i wil have tranny issues later and some newer problem i think. i am in the process of trying to remove the ccm and test the ecm data wire but what a freaking nightmare!!!! any help would be appreciated...
Burning Brakes
Joined: Aug 2003
Posts: 944
Likes: 0
From: Mesa Az
My 90 vette convertible ccm is giving me codes c41 and h41. How much would it cost to bypass the ccm. The car sat for five years and a mouse did a job on the inside dashboard. I had it running when I first started working on it but ran terrible so. Now it doesn't run at all. It cranks but the fuel pump fuse circuit is shut down and the injectors aren't pulsing. If you spray starter fluid it purrs fine. I replaced tps, map sensor, ECM , ignition module, ignition switch, fuel pump and I have a vats bypass chip adapter made from PCM for less so security is not the problem.
The cooling fan were also working until right before the car died and relays are good. I also replaced the fuel pump and injector relays.
I do not want to carb this car out because i know i wil have tranny issues later and some newer problem i think. i am in the process of trying to remove the ccm and test the ecm data wire but what a freaking nightmare!!!! any help would be appreciated...
The cooling fan were also working until right before the car died and relays are good. I also replaced the fuel pump and injector relays.
I do not want to carb this car out because i know i wil have tranny issues later and some newer problem i think. i am in the process of trying to remove the ccm and test the ecm data wire but what a freaking nightmare!!!! any help would be appreciated...
I'm going to ask a dumb question but..you did check the fuses right...?
patience these things can be a pain to work on sometimes, someone here will stear you right.
Supporting Vendor
Joined: Mar 2008
Posts: 1,762
Likes: 14
From: Cumming Ga
H41 = History - Previous logged Cylinder select error
Thread Starter
6th Gear
Joined: Jul 2011
Posts: 6
Likes: 0
Code 41 is the data connection loss from ccm to ECM. I got that from a post on here the other day. The C and H only means "current" and "history". I also seen some post say a module can be built to fool the ECM. I am currently looking into that. My injectors are all reading 16.7 ohms and more. I know I have to pull this ccm out to check the wiring but I can't believe how hard this job is unless I don't know a short cut. Seems these cars are electrical nightmares. Thanks for the input. At least I know I am on the right track.
Le Mans Master
Joined: Aug 2000
Posts: 8,838
Likes: 31
From: Australia
In module 1 ; the CCM module.
Codes mentioned above are in module 4; the ECM module
http://www.corvette-guru.com/uploads...CMCodePull.pdf
That should have removed the need for the fuel enable signal from the CCM.
There is the possibility the ECM is at fault because the CCM expects a response from the ECM
http://forums.corvetteforum.com/c4-s...cm-or-ccm.html
"Loss of Communications
The Serial Data Circuit is a master (CCM)/slave (ECM) configuration.
The CCM polls the ECM. If the ECM fails to respond after 3 consecutive polls (3x200ms/600 milliseconds) a Code 41 sets.
http://www.digitalcorvettes.com/foru...5&postcount=17
Codes mentioned above are in module 4; the ECM module
http://www.corvette-guru.com/uploads...CMCodePull.pdf
There is the possibility the ECM is at fault because the CCM expects a response from the ECM
http://forums.corvetteforum.com/c4-s...cm-or-ccm.html
"Loss of Communications
The Serial Data Circuit is a master (CCM)/slave (ECM) configuration.
The CCM polls the ECM. If the ECM fails to respond after 3 consecutive polls (3x200ms/600 milliseconds) a Code 41 sets.
http://www.digitalcorvettes.com/foru...5&postcount=17
Last edited by rodj; Oct 20, 2011 at 08:19 AM.
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Thread Starter
6th Gear
Joined: Jul 2011
Posts: 6
Likes: 0
Ok. Here's what I got.
CON Digital Volt Meter (DVM) between CCM TERM WC13 (800 TAN) and GND.
I got Continuity.
Now it say to "Repair SHORT to GND in CKT 800".
Any ideas????
I know I am going to need a fsm. But before that when I had the car running and was testing the ECM codes I got multiple cruise control codes and the cruise never worked since I had the car. In one of the post I viewed it said that cruise control was on this circuit so I am thinking this may be the problem. I need to find the wire grounding the system out. It's also not a strong ground when I check it. Just enough I guess to not feed enough volts to the ECM in the communication it has with ccm.
CON Digital Volt Meter (DVM) between CCM TERM WC13 (800 TAN) and GND.
I got Continuity.
Now it say to "Repair SHORT to GND in CKT 800".
Any ideas????
I know I am going to need a fsm. But before that when I had the car running and was testing the ECM codes I got multiple cruise control codes and the cruise never worked since I had the car. In one of the post I viewed it said that cruise control was on this circuit so I am thinking this may be the problem. I need to find the wire grounding the system out. It's also not a strong ground when I check it. Just enough I guess to not feed enough volts to the ECM in the communication it has with ccm.
Safety Car
Joined: Jan 2004
Posts: 3,556
Likes: 13
only a data signal similar to that used on a computer so it doesn't take much for it to drop out
If you suspect you are dealing with a ground problem in one of the connected units , best you can do is isolate each one until you find the problem.
If the problem is with the serial cable (Ckt 800 ) itself being grounded somewhere , you have your work cut out for you because the one splice that links all together (as shown in diagram above) is in the harness behind the CCM
Last edited by vetteoz; Oct 23, 2011 at 07:23 AM.
Thread Starter
6th Gear
Joined: Jul 2011
Posts: 6
Likes: 0
Ok this is what I got so far. I checked the aldl, ac/heat and ccm. All good but still have a slight voltage ground in wire. I really got into the harness but I can't find the hub/junction for the wires to meet.
Question: can I just rewire the ccm to the ECM and include the aldl? I will fix the heat and a/c later. Also I need to take the EBCM off line too, just until I find it, lol. I got the FSM coming this weekend.
Thanks.
Question: can I just rewire the ccm to the ECM and include the aldl? I will fix the heat and a/c later. Also I need to take the EBCM off line too, just until I find it, lol. I got the FSM coming this weekend.
Thanks.
Drifting
Joined: Jun 2010
Posts: 1,853
Likes: 8
From: Westerly RI
Ok this is what I got so far. I checked the aldl, ac/heat and ccm. All good but still have a slight voltage ground in wire. I really got into the harness but I can't find the hub/junction for the wires to meet.
Question: can I just rewire the ccm to the ECM and include the aldl? I will fix the heat and a/c later. Also I need to take the EBCM off line too, just until I find it, lol. I got the FSM coming this weekend.
Thanks.
Question: can I just rewire the ccm to the ECM and include the aldl? I will fix the heat and a/c later. Also I need to take the EBCM off line too, just until I find it, lol. I got the FSM coming this weekend.
Thanks.
