Circuit Description
Traction Control is simultaneously controlled by the EBCM and the PCM. The PCM sends a DELIVERED TORQUE message via a Pulse Width Modulated (PWM) signal to the EBCM confirming the delivered torque level for proper Traction Control system operation. The EBCM supplies the pull up voltage.
Conditions for Setting the DTC
DTC C1276 can be set anytime when ignition voltage is present. A malfunction exists if the PWM signal is out of range or no signal is received for a period of 7 seconds.
Action Taken When the DTC Sets
TCS/Active Handling (if equipped with RPO JL4) are disabled.
| • | Indicators that turn on: |
| Car Icon (TCS indicator) |
| • | Messages displayed on the DIC: |
| Service Traction System |
| Service Active HNDLG (if equipped with RPO JL4) |
Conditions for Clearing the DTC
| • | Condition for DTC is no longer present and scan tool clear DTC function is used. |
| • | Fifty ignition cycles have passed with no DTCs detected. |
Diagnostic Aids
| • | It is very important that a thorough inspection of the wiring and connectors be performed. Failure to carefully and fully inspect wiring and connectors may result in misdiagnosis, causing part replacement with reappearance of the malfunction. |
| • | If an intermittent malfunction exists refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. |
| • | Possible causes for DTC C1276 to set: |
| - | Open in CKT 464. |
| - | CKT 464 shorted to ground or voltage. |
| - | Communication frequency problem. |
| - | Communication duty cycle problem. |
| - | CKT 464 has a wiring problem, terminal corrosion, or poor connections. |
| - | EBCM not receiving information from the PCM. |
Test Description
The numbers below refer to step numbers on the diagnostic table.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the Diagnostic System Check performed? | -- | ||
2 | Check the following grounds, G101 and G108 making sure each ground is clean, tight and free of damage. Refer Ground Distribution Schematics in Wiring Systems. Were any loose, damaged, or corroded grounds found? | -- | ||
3 | Repair ground as necessary. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | -- | |
Is the duty cycle within the range specified in the value(s) column? | 5-25 % | |||
Using J 39200 DMM, measure the DC Hz between J 39700 terminals 6 and B. Is the frequency within the range specified in the value(s) column? | 121-134 Hz | |||
6 | Replace the EBCM. Refer to Electronic Brake Control Module Replacement . Is the replacement complete? | -- | -- | |
7 |
Is the voltage within the range specified in the value(s) column? | Battery Volts | ||
8 |
Is the voltage greater then the value specified in the value(s) column? | 1V | ||
9 | Repair CKT 464 for a short to voltage. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | -- | |
10 |
Is the resistance within the range specified in the value(s) column? | OL (infinite) | ||
11 | Repair CKT 464 for a short to ground. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | -- | |
12 |
Is the resistance within the range specified in the value(s) column? | 0-2 ohms | ||
13 | Replace the PCM. Refer to Powertrain Control Module Replacement in Engine Controls. Is the Replacement complete? | -- | -- | |
14 | Repair CKT 464 for an open. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | -- |
