Year: 2003 148k miles

I'm stuck. Tried just about everything I could research on this site to fix this dang thing. Here's what I have and what I did ...

DIC Messages:
Service Vehicle Soon
Service Ride Control

Dashboard Lights:
Traction Control
ABS

Codes (w/Engine on):
P1571 H C Traction Control Torque Request Circuit
TCS No Comm
C0710 H C Steering Position Signal Malfunction
U1040 H C Lost Communication with XXX
B0441 H C Left Actuator Out of Range

Battery:
12.8v unloaded

Checked Fuses (Ignition in "ON" position):
Under Hood:
5 - ABS TRNS 12.0V
13 - F/PMP 12.0V
16 - PCM 12.0V
17 - THROTCONT 12.0V
18 - INJR 2 12.0V
19 - ENG ING1 12.0V
22 - INJR 1 12.0V
23 - PCMB 12.0V
51 - RTD MAXI 12.0V
52 - ABS MAXI 12.0V
53 - ABS ELEC 12.0V

IP Inside:
9 - BCMA 12.0V
18 - HVAC 0.1V
19 - IPC 12.0V
21 - BTSI 12.0V
23 - BCM 13 12.0V
25 - BCM1 & IPC 12.0V

In addition to checking fuses identified above, I also:
* Checked ground connections (rewired the connector terminals, checked under battery, etc).
* Did the ignition switch repair - Pitting had occurred, cleaned per procedure, etc.
* Did the EBCM solder procedure. The solder joints were good, but re-did them anyway.
* Checked accordion door connections

I'm not real good with checking circuits, actually pretty bad to the point where I'm about to give up and take it somewhere, but want to give the forum a shot at what else I can do before opening up my wallet and letting my hard earned money pour out.

Thanks everyone

 

Bad to Worse

Pulled the accordion on both sides and reworked a couple of pins that looked a little misshapen. Now I have no driver side door functions. Also have new codes and stuff:

(in addition to the previous codes)
U1160 HC
LDCM No Comm
RDCM No Comm
SCM No Comm

I ran some continuity checks on the ground wires and all checked out except the small ground wire in the short blue connector in the "J" position. This is the small black wire next to the silver wire with the clear tubing. Should I be getting a ground continuity from this wire? If so, can you tell me where it grounds to the frame?

Also pulled the caps off the star connectors next to the PCM. The ones with the black tape across the top. Just looked, then put the caps back on. Nothing looked bad there.

Hoping someone can shed some light.

Thanks

Clarification on driver side controls:
Only partially disabled. Still have "Unlock", mirror adjustments and memory. No "Lock", windows or panel lights. Same on passenger side.

 

Spent all day rerunning the meter over everything. Even jumpered that ground wire in the blue door connector to ground, no change. Pulled G201 & G202 to verify connectivity. All looked pristine. Losing hope.

Anyone know a good vette shop in Northeast Dallas area that's good with a Tech II? Please don't make me go to Chevy!

 

A funny thing happened on the way to the forum ...

Went back over the two Star connectors and what do you know, the pin bus on one of them had fallen out of the cap when I went to put it back on last time. I found the pin bus laying underneath the connections. Stuck it back in and now I'm back to the original TCS problem. Some day ..

 

Either the EBCM isn't getting any power, there is an issue with the Class 2 communication buss or the EBCMs internal electronics have taken a major dump. I suspect loss of power is most likely.

Recheck fuses 5 and 52. Don't turn on the ignition. Pull the fuses and inspect them to see if they are blown. Look at them and if you can't tell if the fuse is blown use an ohm meter or continuity checker/meter to see if they still have continuity. Fuse 5 feeds both the EBCM and the ESC however, if it was blown you shouldn't have gotten the C0710 code. Check it anyway. Fuse 52 feeds the EBCM alone.

Don't know what to tell you about Fuse 53. The schematics don't show it connected to anything. Not in the ABS schematics and not in the Fuse Box schematics. However, that doesn't mean it isn't used. Especially if there is a fuse in the location. Pull it and check it as well.

If the fuses are OK then you may have a wiring issue where the power or ground wires have been disrupted. If the EBCM has power and ground continuity at its connector then you need to see about any Class 2 Databuss issues that might exist.

Bill

 

Thanks Bill

I sent the EBCM off to myairbags.com to at least have them check it out. They were only $59 bucks and life time warranty, but more importantly, I wanted someone to confirm it was still alive or dead. In any case, I'll run through the fuses again as you suggested. Should have the EBCM back in a week and will post my results.

 

Update:

Received the ECBM back and although they claim to have "rebuilt" the thing, they couldn't tell me if it was DOA or they just classify NTF as needing a rebuild to justify the fee. In any case, it didn't clear my codes (yes, I reset all of the codes after reinstalling it but they came right back). Rechecked all of the fuses once again and cleaned all of the contact points. Looks like the steering wheel position sensor may be next on the list. Not sure this is something I want to tackle.

I'll post any changes as they happen in case anyone else is researching the problem.

 

Buy a new/rebuilt one. Yours cant be fixed.

 

"Buy a new/rebuilt one. Yours cant be fixed."

Not sure what you are meaning. My ECBM can't be fixed? Are you thinking it might still be the EBCM that's bad? I would have hoped that the place I sent it to would have indicated that it was not repairable if that was the case, but they just indicated it was "rebuilt".

 

There is a thread somewhere with the exact same thing you are going through. Had TCS no comms. Sent it out to get fixed and they sent it back to him saying it was not bad. Eventually he replaced it and thats what fixed it.

 

Yea, I remember seeing that one too. Also saw Bill Curlee say the same thing several times - that they can't fix these things. I just figured if it wasn't throwing the C1255 code, maybe the EBCM could be fixed. Just for grins, I pulled the wheel speed sensor pigtails yesterday and they all looked fine. Same with the SWPS connection. Saw a rebuilt EBCM for $350 so I guess that's where I'm going next.

Thanks again.

 

Update:

Bought a new EBCM. Shout out to Roger Dean Chevrolet for not gouging me. Brand new in the box $569.

Still having a little trouble. Reset all of the codes. Warning lights went out. Everything looked good for about five minutes, then got hit with various codes, but in most sequences, the TCS No Comm didn't come back. After clearing the codes again while driving, eventually the original codes posted came back along with TCS No Comm and stayed on until I shut the car off.

Acts like it wants to cooperate, but something keeps knocking it out. Anyway, going to keep at it. Will post any updates as they occur.

 

Same as before:

P1571 H C Traction Control Torque Request Circuit
TCS No Comm
C0710 H C Steering Position Signal Malfunction
U1040 H C Lost Communication with XXX
B0441 H C Left Actuator Out of Range

Actually, it seemed odd to me that it reacted like it wanted to work correctly by initially clearing all the codes, but then returning after five minutes so I researched a little further and discovered there's a learned handshake process that needs to be done when installing a new EBCM. So, tomorrow when I have half an hour to do the process, I'm going to see if that clears the codes for good.

 

There is no handshake procedure that needs to be done when installing a new ebcm. It is plug and play.

 

Yeah, the BCM procedure doesn't work for the EBCM. Even though the new EBCM provided brief glimpses of coming back to life as previously noted, it still bails out and reverts to the original codes posted. At least that's more than the old EBCM was doing. Anyway, going to check all of the grounds one more time but looks like I'm headed to Chevy. Looking forward to my final post on this issue.

 

When you replaced the EBCM did you inspect the connector to make sure all of the connector pins are clean and making good contact? P1571 indicates the PCM isn't getting the requested torque signal. That could be due to low voltage or to a bad connection inside that connector. Same goes for the steering sensor code. The DC power, ground and all of the sensor signals and reference voltages go through that connector. Poor connections are one of the major reasons electronic devices fail.

Bill

 

Good call, Bill

I'm proud to say that I can now write the post I have been waiting to write. Before reading Bill's post I went out and re-re-re-checked the grounds. Although I was getting a good ground reading from the EBCM connector grounds using the meter probes, I had a wild hair to pop the main ground connector pin from the harness and take a look. After reworking the pin (bending the contact strip down, cleaning any build up, etc.), plugged it back in and and BAM! - all codes went to history, cleared them and now code free! Apparently, although I could get a good reading touching the pin with the meter probe, it wasn't making good contact when plugging it in to the EBCM. Even though I had cleaned that pin before, I hadn't removed it from the harness.

Still feel like the original EBCM had gone bad to start this mess. But I'm not plugging it back in to confirm. I'm done messing with it as long as it continues to work.

Thanks everyone for stopping by and especially to those that tried to help.

Chalk another one up to the forum!

 

Good write up and response on the C5 bad EBCM problem Etc.
It was good you did a follow up stating your problem was resolved.
I am having the same problem on my 2000 Vette Convertible or close to and none of the basic inspections show any positive results or cures.
Returned from a car show this passed weekend and the power window would not go up, passenger side, after checking all the fuses and tapping the grounds nothing except now both windows do not work along with power door locks and lights in the door controllers. I pulled the DIC codes and what I got was AO-LDCM No COMM, Left Door Control Module. A-RDCM NO COMM. Right Door Control Module. A6-SCM NO COMM, Seat Control Module. BO-RFA 3 Codes
U1096 (H) Loss of Comm., IPC, (Instrument Panel Cluster). U1064 (H) Body Control Module U1016 (H) PCM Loss of COMM. 99 HVAC U1160 (H) (C). My next step this weekend will be to remove all the grounds and clean and hope this clears things up. If anyone know something I might have skipped or missed please inform.
Thank You!

 

Which one of the pins on the harness is the ground connector pin? I am having a problem with the EBCM myself and checked a few of the ground connections and they look like they are in great shape. I have had 4 EBCM's on this car and none work, telling me that it should be a grounding issue.

 

There are two black wires on one side of the connector harness, a thin one and a thick one. The thick one is the one I re-worked and I believe I had to remove the harness cover to get to it. Just slides off after releasing the snaps. Need to slide a very small screw driver or as in my case a small straightened paper clip into the harness to release the pin so that it slides out. Rework the pin making sure the contact clip is bent down far enough to make good contact and put it all back together.