Question: C5 Left Door/ DIC faults

[jrhott]

THe Psycho is acting up again and the dealer can't find the issue.
Symptoms:
Left door controls go dead and LDCM looses communications. Your are able to get the left door controls to light up by swinging the door open back and forth. Now you can't find fault. Connectors down near left lower side under instrument panel are tight.
Second thing that has happened is massive light up of faults on instrument panel including no communications to LDCM, PCM, HVAC, etc. Temperature, pressure, and gas gage go dead. Reduced engine power warning come up on DIC. ABS and TRaction control lights eluminate. No actual average MPG reading shown on DIC. I could not notice any reduced engine power.
If you turn off ignition, faults will reset. I did notice when I went over a bumpy road the faults were able to be reset and the gauges came back.

Anybody have any ideas how to the gremilins from the Psycho?

 

[gmjunkie]

THe Psycho is acting up again and the dealer can't find the issue.
Symptoms:
Left door controls go dead and LDCM looses communications. Your are able to get the left door controls to light up by swinging the door open back and forth. Now you can't find fault. Connectors down near left lower side under instrument panel are tight.?

Yepers!!
Been there,Done that!!On about 8-10 different cars,Got the Shirt and Skinned knuckles to go with it!!
Each one just a little different,But judging from your post,It's in that plug or a broken wire in the door harness where it bends allot!!Tell the boys to check the plug out real good for pins not seated good and pushing backward out of the plastic connector. If that don't do it, remove the door interior trim panel,get out the digital probe and start checking every wire from the plug back to each connector inside the door while moving the harness around between the door and hinge pillar!!(Fixed several with broken wires!) Also have them check and clean the grounds on the inside of the hinge pillar under the kick panel!!

Second thing that has happened is massive light up of faults on instrument panel including no communications to LDCM, PCM, HVAC, etc. Temperature, pressure, and gas gage go dead. Reduced engine power warning come up on DIC. ABS and TRaction control lights eluminate. No actual average MPG reading shown on DIC. I could not notice any reduced engine power.
If you turn off ignition, faults will reset. I did notice when I went over a bumpy road the faults were able to be reset and the gauges came back.

Anybody have any ideas how to the gremilins from the Psycho?

First thing I'd do here is, Check and Clean Every Ground Lug on the vehicle,Including the ones on the back of the engine not shown below!!~!!

 

[jrhott]

Grounds have been cleaned. I suspect it is a chaffed wire or something like that. Last night I was able to inetrupt power to the door at will by just moving the door back and forth. They can't duplicate it today.

 

[jrhott]

On a separte note, I have come acrosseed an issue with C5 front spindle bearing cartridges being loose. It appears this is related to cars being used for autocross where the car is being thrown around. I found the upper 2 bolts securing the cartridge loose (snug). Another guy's wheel on a Z06 was seriously loose. It was intially thought to be a bad tie rod end. This was caught in tech.

 

[jrhott]

Can you tell me exactly on the engine where these grounds are? THe dealer could not find the ghosts. I checked the pillar gounds, clean. I also am getting PCM p0137, and some HVAC faults.

 

[gmjunkie]

Can you tell me exactly on the engine where these grounds are? THe dealer could not find the ghosts. I checked the pillar gounds, clean. I also am getting PCM p0137, and some HVAC faults.

Is this a GM Dealer??? If so,Maybe they should go back to Milking,Stump Breaking Cows and Making Cheese!!!:L:L:L

It's way down under all this mess,they will probly have to access them from under the car!!I don't remember if if there around,under the starter or on one of the bell housing bolts!!

It's raining here like a Angus Bull U-Ryan-Nate-Ting on a Flat Rock for days now or I'd put my car in the shop raise it up and look!

 

[jrhott]

I will do that. I cleaned another ground on the driver side pillar. It was cleean, what a bear. Went to the left pillar, looked at it and said well thats another day. What another bear. I have gooten very proficient at resetting faults with my thumb and finger. PCM P0137 and HVAC faults. I am starting to think this is a reincarnation of an ols Spitfire I owned with the wonderful Lucas Electrical Systems.

 

[Hib Halverson]

Why do Englishmen drink warm beer?

Because they have Lucas refrigerators.

Ok...seriously...that you can sometimes cause the problem by opening and closing the door is a very obvious clue that the problem is most likely an issue with wires and connections.

While it's always a good idea to check grounds, in this instance, I'll guess grounding is not a problem as the ground for the door modules and so forth is probably far enough away that it's not affected by movement caused by door opening and closing.

What I'd do is
1) You've already mentioned looking for wires which are chaffed.
2) Look for broken wires....and, to do this, you may need to unwrap harnesses bound with black tape.
3) Closely inspect connections looking for loose pins or wire crimps to the pins that are faulty or corroded. Movement of door opening and closing may move the wires bound to those connectors enough that and open or high resistance occurs.
4) Remove the door panel, turn the key on and "wiggle" the wires and connections you can reach. You might be able to duplicate the problem that way.

As for all the DIC and IP problems, again, I'm going to suggest wires and connections issues, but...you already knew that.

 

[jrhott]

Could the LDCM cause a loss of communication to the other modules. PCM, HVAC, Etc. When the Christmas tree lit up, the door was dead. I hit a bump and all the lights came on including ABS, traction control. Temp gage, oil press gage, fuel gage went dead.

 

[gmjunkie]

But judging from your post,It's in that plug or a broken wire in the door harness where it bends allot!!Tell the boys to check the plug out real good for pins not seated good and pushing backward out of the plastic connector. If that don't do it, remove the door interior trim panel,get out the digital probe and start checking every wire from the plug back to each connector inside the door while moving the harness around between the door and hinge pillar!!(Fixed several with broken wires!)

Why do Englishmen drink warm beer?

Because they have Lucas refrigerators.

Ok...seriously...that you can sometimes cause the problem by opening and closing the door is a very obvious clue that the problem is most likely an issue with wires and connections.

While it's always a good idea to check grounds, in this instance, I'll guess grounding is not a problem as the ground for the door modules and so forth is probably far enough away that it's not affected by movement caused by door opening and closing.

What I'd do is
1) You've already mentioned looking for wires which are chaffed.
2) Look for broken wires....and, to do this, you may need to unwrap harnesses bound with black tape.
3) Closely inspect connections looking for loose pins or wire crimps to the pins that are faulty or corroded. Movement of door opening and closing may move the wires bound to those connectors enough that and open or high resistance occurs.
4) Remove the door panel, turn the key on and "wiggle" the wires and connections you can reach. You might be able to duplicate the problem that way.

As for all the DIC and IP problems, again, I'm going to suggest wires and connections issues, but...you already knew that.

I believe I said something to that effect in a earlier post!If thats not been checked out yet,there is no reason I should wast anymore time here!!I've got 2 Corvettes in Marion to go pick up for Nationwide Ins. that a Oak Tree fell on yesterday from the saturated ground,Thats like $$$$ in the bank!!
Later!!

 

[jrhott]

Is this a GM Dealer??? If so,Maybe they should go back to Milking,Stump Breaking Cows and Making Cheese!!!:L:L:L

It's way down under all this mess,they will probly have to access them from under the car!!I don't remember if if there around,under the starter or on one of the bell housing bolts!!

It's raining here like a Angus Bull U-Ryan-Nate-Ting on a Flat Rock for days now or I'd put my car in the shop raise it up and look!

Hey,
The 2001 is acting up. It will stall with no warning. No Faults, starts right up.

 

[WB6HRO]

I had a communication problem on my 02. The problem stems from the fact the serial communications is at a low current and any voltage drop in a connector.....no communications.

First disconnect the battery!

So I pulled the rubber bellows that is between the door and the body loose at the body side. Then you can pull out the connector. Now bend the pins just slightly so they will wipe better on the female side. (if you didn't disconnect the battery you can blow fuses, when you touch two pins together) Plug the connector in and out several times.

Put back together and hook up the battery again.

It's one difficult to fix if your tech is a parts changer and not into actual diagnostics.

 

[c4c5specialist]

HI there,

Lets get back to basics.

Each situation is different and requires different tactics to actual diagnose the condition.

Loss of communications can be caused by ANY MODULE AT ANY TIME>

BUT THAT IS ALSO YOUR KEY. What works?? Doors, HVAC, windows ??????

Each situation is different and each REQUIRES attention to detail.

And to the other posters, ANY of the theories presented can create conditions, HOWEVER, ONLY ONE condition will give you the problems with doors not working and the entire communications system failing.

Joes post directly above this is what your looking for, and the terminals are available from GM to replace the bad ones without replacing the entire wiring harness.

Allthebest, c4c5