Help! Module 1 C41 Module 4 Err Module 9 H72

[1992BearC4]

1992 C4 A/T 132,000 miles. I have owned the car for about 6 years and the first 4 1/2 were great no major problems. The last year and 1/2 have been down hill from there. In that time some work was done. Number 1 was a aftermarket CD player after reading not sure if a Bose Bypass harness was used as only two speakers work and the noise that is picked up is awful. Also SYS flashing in dash. Number 2 the drivers side headlight malfunctioned and ripped out the #2 cooling fan relay (right after that the car overheated) that was replaced with a new pigtail and relays. Number 3 the car came to a point where it would not start took it into a local shop $500.00 later it did run with no explanation of what was repaired (this repair lasted only a few months !!) Now we are in the present the car will not start. The car is showing CCM codes C41/H72/H74. The ECM says ERR and I can not even manually pull codes with the jumper trick. and module says H64 H72. I do have access to Mitchell On Demand and have gone through the flow chart for C41 but what does not make sense is the tests are saying nothing is wrong ??? Please anyone with these symptoms or that have experienced this in the past please help !!!!. Also I have tried 2 different ECM's with no change but still with the same MEMCAL.

Thanks

 

[Hib Halverson]

1) It was not clear in your post if the "aftermarket CD player" is an add on device and the existing Bose system is still in the car or your "aftermarket CD player" is really an aftermarket receiver which is AM/FM and CD.

"SYS" on your IP is because of the CCM codes

CCM codes:
C41 is a current code identifying loss of ECM serial data. When this code is present, the car usually will not start because the CCM cannot communicate with the ECM to enable the fuel injectors.
H72 and H74 are are history codes identifying a fault with the LCD dimming circuit. Those codes may set when an aftermarket receiver has not been properly installed.

You likely need a scan tester because when DTC41 sets and the ECM will not flash codes, DTC51 is, also, usually set but, since you can't use flash code diagnostics, you need a scan tester to read the code. DTC51 is a Mem-Cal error which sets if: 1) wrong Mem-Cal is installed, 2) Mem-Cal is not installed correctly or 3) the Mem-Cal is faulty.

You said

and module says H64 H72.

But you did not say which module. Assuming you meant ECM codes...
H64 is a history code identifying a problem with the O2S on the right bank. That side of the engine was running lean at one time but was not lean during the last cycle.
H72 is a history code identifying a fault with the transmission gear selector switch which sets when ECM detects an open somewhere in the selector switch circuitry.

My gut feelling tells me that you first better get a scanner to resolve the DTC41 and you need to carefully inspect all wiring and connections between the ECM and the CCM along with other wires and connections at the ECM.

I'd also check all engine controls grounds.

Lastly, forget "Mitchell on Demand".
Buy the 1992 Factory Service Manual.

You've got some diagnostic challenges ahead of you.
Good luck.

 

[1992BearC4]

The AM/FM CD player is aftermarket and yes the bose system is still in the car. The Codes H72 and H64 were from the EBCM/ASR behind the drivers seat.
I have a Snap on Solus Ultra and it will not communicate with the ECM ????? I did go through the Ground location chart and everything was OK ?

 

[Hib Halverson]

The AM/FM CD player is aftermarket and yes the bose system is still in the car. The Codes H72 and H64 were from the EBCM/ASR behind the drivers seat.
I have a Snap on Solus Ultra and it will not communicate with the ECM ????? I did go through the Ground location chart and everything was OK ?

The aftermarket AM/FM CD in the dash is causing the dimmer circuit fault.

The Snap-On Solus Ultra is definitely a high-end tester. If it will not communicate with the ECM, you've got a serious problem somewhere in the serial communications bus. I'd start by researching the parts of Vol 2 of the Factory Service Manual which discusses loss of serial communications with a scan tester along with the diagnostic data for the other serial communications loss fault.

As for the EBTCM codes:
H64 is a TPS fault
H72 is a serial data link fault

That you have multiple fault codes relating to loss of serial data communications is indicative of where to start.

You have a great tester. All you need is the FSM and a DMM and lots of time and patience. You can buy the Factory Service Manual from CAC Sponsor Zip Products.
http://www.zip-corvette.com/Product...e+Manual&Referer=&Alias=&ptct=SGR-SR&CTitle=&

Good luck.

 

[Ken Anderson]

If the car won't crank & no fuel pumps, then your CCM/BCM is due for repair. Have you jump started your car? The "shop" probably did and that was bad for the CCM. 41 is a communication error between the CCM & ECM

 

[1992BearC4]

Got a hold of the FSM for my vette !

Got the right flow chart/diagnostics for the C41 and got down a few steps and basically it is telling me that there is a short to ground from CCM Pin E13 on the green connector of the CCM. I found what is called Ground E and that is the main grounds for the ECM/CCM/EBCM/HVAC Programmer (optional)
When I test E13 to ground I get 35,000 ohms yes that is correct as a local auto electric friend brought over his multi meter and got the same readings as I did. So I found Ground E (left rear of engine not on bell housing). Long story short valve cover gaskets were replaced not to long ago and low and behold that ground with all the leads attached is literally covered in old oil from the old faulty valve cover gaskets so I guess having that much resistance could cause a major data line malfunction ????????

 

[1992BearC4]

Ground E Left rear of engine (not on bell housing)

Well took the time today to clean and inspect ground E which is the main grounds for the CCM/ECM/EBCM/HVAC. Took apart and wire brushed and wire wheeled all areas put everything back and got almost the same reading except for 32,000 ohms instead of 35,000 ohms. I don't know where to go from here and I need some ones expertise and how to find the Short to Ground in the CKT 800 (serial data lines) winter will be here soon and need to get it running before it sits for another 6 months!!! Thanks

 

[Hib Halverson]

Unfotunately, I'm going to have to "lie low" on this thread for a couple of weeks.

I'm on a two week road trip away from the shop, where I keep all my service data, but....anytime you have a round with 35K ohm resistance, there's a problem. You need to work back up the ground wire(s) until you find where so much resistance is located.

 

[1992BearC4]

So what you mean is each ground wire that is attached to ground E needs to be checked until you find the problem ? Is there an tips as to which ground wire could be the culprit as it seems as everything is talking except the ECM ? Also would it be any value to undo the splice pack at S222 and measure each wire separately ? Thanks

 

[1992BearC4]

Can anyone out there tell me if tracing back up the ground is talking about going from where all the connections meet and bolt into the block and then up from there ? To each module ? I did do a continuity test for all the tan wires on CKT 800 and they were all around 0.04-0.02 ohms. I am 99% sure each module is working, it will start and run and the security light does go out once started. Sorry for all the questions I am so beside myself I don't know how to get this car running as winter is coming !!! Thanks in Advance.

 

[vetteoz]

I did do a continuity test for all the tan wires on CKT 800 and they were all around 0.04-0.02 ohms. I am 99% sure each module is working,

All I know

Corvette Forum : DigitalCorvettes.com Corvette Forums - View Single Post - pulling my hair out

 

[1992BearC4]

Thank you for that I have gone through that flow chart and got the short to ground in ckt 800 I guess I just need some tips and help on how to properly find the short to ground as all tan wires have good continuity ?

 

[1992BearC4]

Anyone have any tips on my last post still at a stand still. Gonna snow here soon would really like to get somewhere ? Thanks

 

[1992BearC4]

Ready to Give Up !!!!

I have laid low on this problem and tried to get my head clear as I have little time left before it gets towed to storage for the winter season. I found this article online about testing Serial Data Lines and associated grounds in which they said to hookup a DVOM to the tan wire at the DLC and hookup the other probe to the common ground at the DLC. From there they said to unhook modules or ground wires until you get an OL on the DVOM. After I did all this it came to the 2nd plug on the CCM (the one with no CKT 800 wires on it) once that was disconnected the short went away. Does this sound like a possible issue or am I just throwing dust at the wind ? If not could some please post any correct info step by step on how I can at least head in the right direction with this problem. Thanks for all the help already !!!!

 

[Hib Halverson]

Be very carful about using an ohmmeter in this manner because they apply a voltage to whatever's being tested.

I think you'd be better off getting the Factory Service Manual and following the diagnostic instructions for DTCs in question.

 

[Ken Anderson]

Ccm

I have laid low on this problem and tried to get my head clear as I have little time left before it gets towed to storage for the winter season. I found this article online about testing Serial Data Lines and associated grounds in which they said to hookup a DVOM to the tan wire at the DLC and hookup the other probe to the common ground at the DLC. From there they said to unhook modules or ground wires until you get an OL on the DVOM. After I did all this it came to the 2nd plug on the CCM (the one with no CKT 800 wires on it) once that was disconnected the short went away. Does this sound like a possible issue or am I just throwing dust at the wind ? If not could some please post any correct info step by step on how I can at least head in the right direction with this problem. Thanks for all the help already !!!!

Repair/replace CCM as my post of 9/18 suggested. You are dusting away. Hib is correct re: digital voltmeters,

 

[1992BearC4]

Thanks Ken and Hib: Any references on where to get a CCM from new/rebuilt or send in this one ? You are dusting away ? Thanks again it seems like I am actually heading in a direction finally !!!

 

[Hib Halverson]

I suspect the CCM for MY92 is long-since discontinued by GM.

As for rebuilts....I am not aware of sources for them, but that's only because I have not researched them.

Sorry I can't be of more help.

Good luck with your search.

 

[1992BearC4]

Hello everyone been away for a while. Long story short I had A1 Cardone rebuilt the CCM and I sent the ECM in also I have both in the car now and still have the Module 4 ERR but I do not have any current DTC in the CCM or the EBCM relating to Serial Communication. It did the Key relearn and it will try to start but it dies within a few seconds and smells like it is flooding out. I do have a reoccurring history code for TPS in the EBCM ? Not sure if that is even relavant ? Thanks in advance.

 

[ecss]

Hello everyone been away for a while. Long story short I had A1 Cardone rebuilt the CCM and I sent the ECM in also I have both in the car now and still have the Module 4 ERR but I do not have any current DTC in the CCM or the EBCM relating to Serial Communication. It did the Key relearn and it will try to start but it dies within a few seconds and smells like it is flooding out. I do have a reoccurring history code for TPS in the EBCM ? Not sure if that is even relavant ? Thanks in advance.

If the CCM was re-manufactured the Odometer reading should read 0.

If you short pin A to pin B and turn the ignition On, do the fans come on and does the service engine soon
indicator blink 12 three times then repeat if there are no codes set?

Something is strange because in order for the ECM to pulse the injectors the CCM must communicate with the ECM to enable the fuel enable disable signal. (FEDS) and you're smelling gas?

Disconnect the fuel pump fuse while you diagnose the communication problem. Otherwise you may be filling the cylinders with fuel.