Need Help with Codes - ABS, Active Handling/Traction Control

[ArrestMeRed]

Started getting a few DIC messages and warning lights coming on while I was on the Hot Rod Power Tour this week. Started Sunday when we were between Arlington and Tulsa. Active Handling/Traction Control light comes on intermittently. ABS light comes on intermittently as well. No pattern to it. Nothing specific seems to trigger it. Car runs fine, stops fine. No noticeable problems other that these pesky warning lights and DIC messages. Here’s what the DIC Displays at times:

Service Traction System
Service Active Handling

Here are the codes displayed on the DIC:

10 PCM
NO CODES

28 TCS
C1276H
NO COMM.
U1000H
U1016H

40BCM
U1096H

58 SDM
U1040H
U1096H

60 IPC
U1040H
U1160H

80 RADIO
U1096H

99 HVAC
NO CODES

AO LDCM
B2282H
B2284H
U1064H
U1096H

A1 RDCM
B2283H
B2285H
U1064H
U1096H

A6 SCM
NO CODES

BO RFA
U1096H

I have done a few searches and read most of the posts. What do you think is causing this and what do you think I ought to do about it. I have the key to what the codes mean, but not much help. Thanks for your help! Mike

[PimpinZ06]

It is a bad wheel sensor connection probably. Take it to Chevy. Just happened to me after being on the dyno.

[ArrestMeRed]

Originally Posted by PimpinZ06

It is a bad wheel sensor connection probably. Take it to Chevy. Just happened to me after being on the dyno.

Thanks Pimpin! I hate to take it to the dealer because it hasn't been back since new, but sometimes I guess we must do things that we don't want to do. Mike

[pbadad]

how do you spell relief...... WARRANTY

[Subdriver]

All those codes are History, not Current.

I checked the service manual for C1276 and it says:
- Electronic Brake Control Module (EBCM) detects that delivered torque signal is out of the valid range
- EBCM does not receive the delieverd torque signal

Actions:
- EBCM disables TCS/VSES for duration of the ignition cycle
- PCM will store conditions which were present when the DTC set as Fail Records data only
- Traction Control and Active Handling indicator turns ON
- DIC displays: Service Active Handling, Service Traction Control
- ABS remains functional

The EBCM clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles
The PCM clears the history DTC when a current DTC is not detected in 40 consecutive warm-up cycles

Corrective actions (less all the tests)
- inspect EBCM ground and PCM ground
- test delivered torque signal circuit for open, short, high resistance
- inspect for poor connections on PCM
- inspect for poor connections on EBCM
- replace PCM
- replace EBCM

The description of the system indicates the PCM and EBCM talk to each other via pulse width modulated signals to control torque. The EBCM controls torque by applying front brakes (never knew that). The PCM controls torque by retarding timing and turning off fuel injectors.

Most of the other codes are comms type codes for the door modules, radio, etc. Those codes look like they trip on voltages outside 9-16 volts.

It may be possible you have a loose connector in the ABS system causing the torque issue, or it may be a voltage problem causing all of the codes.

You should probably take it in. Without the scan tool, it will be tough to check.

[ArrestMeRed]

Thanks for the info! Exactly, where is the PCM and the EBCM? I guess I'll take it in as bad as I hate to. We don't have good dealer service in this area.

[ROSSO Z]

Do a search on my handle and this subject. Many posts.

Check the EBCM wiring harness just in front of the alternator pulley. Mine rubbed through and caused problems. I'm having it replaced next week.

Keep us informed.

[Subdriver]

As Rosso said, the EBCM is on the passenger side of the ABS block which is right in front of and below the alternator. It is identifiable by the six hard brake lines going into it. The wires plug into it from the bottom passenger side. It is actually easier to see these from the bottom of the car.

The PCM is in the front passenger fender behind the RF wheel.

Here is a great how to for replacing the PCM which has enough info to find it and look at your wiring harness (again, easier to see the wiring harness from under the car).

PCM Replacement

[ArrestMeRed]

Thanks Subdriver! In your previous post you said that a voltage problem could be causing all the problems. I think you may be right on track because yesterday it was really hot, so I turned the AC fan on high and was watching the voltage on the DIC. The ABS light was on as was the light that comes on when you turn the traction control off. The fan speed slowed down for a sec and the voltage dipped for an instant and the ABS light went out. The traction control light stayed on, but the ABS went out. Don't know what's causing the voltage to vary? Car runs fine and stops fine, but don't like driving around without Traction Control some of the time. Seems like everything is fine until all the systems are completely warmed up. Then I start getting these pesky lights and service soon warnings. Also, just 2 times during all this, I've had the 1 to 4 Shift light come on. I have the Cags Defeat fix but why would this light come on??????????? Drove 50 miles to try to get the car in the shop, but couldn't since they were booked for the day. Confused in MS. Mike

P.S. - Pulled the car out yesterday to get the Hot Rod Power Tour road grime off of it. You know try to pamper it a little....... and when I was pulling it back in the garage, it was dark so I turned on the headlights. When I got inside and turned the lights off, there was a loud gear stripping noise when the lights went down. I couldn't get it to quit except to leave the lights in the up position with the parking lights on. Had to unhook the battery................This is a car that has never been back to the dealership since new. I guess it could be worse, but when it rains here lately, it seems to pour......

[Subdriver]

I would guess all your problems are related since they are coming all at once.
Who knows. Could be a shorted wire somewhere, or maybe something as simple as a dying battery.
Good luck sorting it out.

[ArrestMeRed]

How long do these batteries normally last. My car has 9300 miles on it and will be 3 years old next month. It was an early '02 model. OBTW, the battery has completely died several times and had to be jump started due to sitting idle during the winters for anywhere from a month to a couple of months at a time. Thanks! Mike

[ArrestMeRed]

OK, Have been out of town lately and just back yesterday. Rested up and decided to tinker with the Z to see if I could find any obvious problems. Battery was disconnected for over a week while I was out of town. Checked all the connections I could find. Nothing appeared to be loose. Turned switch on and put DIC in manual mode. Cleared all the existing codes mentioned earlier. Started car and let it run awhile with AC on and fan speed on high. Was raining so didn't take it out on the road. In fact, didn't even move the car, just let it run til it warmed up completely. Monitored the voltage and it didn't get higher than 13.2. Also didn't go lower than about 12.6 to 12.8. Revved it up a couple of times and the voltage did not get much above 13.0. After car warmed up, got the message to Service Active Handling/Service Traction Control. The Traction Control light came on indicating that the Traction Control was off. Retrived Codes as follows:

28 TCS NO COMM.

58 SDM U1040 H C

60 IPC U1040 H C

Mike

[ArrestMeRed]

Any thoughts?

[Ahroun]

Oddly, Im seeing a similar thing. Though the dealership I took my Z to were all about charging the heck out of me for diagnostics.

Tonight, in fact, I heard the chimes and saw the "Service Active Handling" message on the IC. BUT I still had AH/TC. Kind of weird, huh.