GM Service Manual Online
For 1990-2009 cars only

Object Number: 393814  Size: MF
ABS Components
Antilock Brake System Schematics
Data Link Connector Schematics
Handling Electrostatic Discharge Sensitive Parts Notice
Handling Electrostatic Discharge Sensitive Parts Notice

Circuit Description

The PCM monitors various parameters and will not allow traction control operation if any parameter falls below a specified value.

Conditions for Setting the DTC

The PCM detects a malfunction and then causes TCS shut down until the malfunction has been corrected.

Action Taken When the DTC Sets

    • A DTC C1278 is stored (This is a temporary malfunction)
    • The ETS/TCS is disabled
    • The TRACTION OFF indicator is turned on
    • ABS remains functional.

Conditions for Clearing the DTC

    • The condition for the DTC is no longer present and the scan tool clear DTC function is used
    • 100 ignition cycles have passed with no DTCs detected

Diagnostic Aids

This code is for information only. As an aid to the technician, this code indicates that there are no problems in the ABS/ETS/TCS system. Any further references for diagnostic information should be taken from Engine Controls.

Step

Action

Value(s)

Yes

No

1

Was the Diagnostic System Check performed?

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Go to Step 2

Go to Diagnostic System Check - ABS

2

  1. Install a scan tool.
  2. Turn the ignition switch to the RUN position, engine off.
  3. Using a scan tool, read the DTCs.

Are any other DTCs set?

--

Go to Diagnostic Trouble Code (DTC) List for the appropriate DTC

Go to Step 3

3

Is DTC C1278 set as a current code?

--

Go to Step 5

Go to Step 4

4

  1. Start the engine and test drive the vehicle at least 16 km/h (10 mph) while monitoring the scan tool for DTCs.
  2. Repeat the above drive cycle sequence two more times.

Did DTC C1278 set in the last three drive cycles?

--

Go to Step  5

System OK

5

Perform the Powertrain OBD System Check. Refer to Powertrain On Board Diagnostic (OBD) System Check or Powertrain On Board Diagnostic (OBD) System Check in Engine Controls.

Did the vehicle pass the OBD System Check?

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Go to Diagnostic System Check - ABS

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