For 1990-2009 cars
ABS Components
Cell 44: ABS/TCS Switch, UART, PCM, and Traction Control Switch
Handling ESD Sensitive Parts Notice
Cell 50: UART Serial Data Line

### 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 TCS is disabled

• | The TRACTION OFF indicator is turned on

• | If the TCS is no longer inhibited, the indicator will be turned off but the DTC will be stored

### Conditions for Clearing the DTC

• | The condition for the DTC is no longer present and the scan tool clear DTC function is used

• | 50 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/TCS system

### Test Description

The numbers below refer to the step numbers on the diagnostic table.

1. This step checks if DTC C1278 resets.

#### DTC C1278 TCS Temporarily Inhibited By PCM

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Was the Diagnostic System Check performed? | -- | Go to Step 2 | Go to Diagnostic System Check
2 |

1. Turn the ignition switch to the RUN position with the engine off.
2. Using a scan tool, read the ABS/TCS DTCs.

Are any other DTCs set?

--

Go to Diagnostic Trouble Code (DTC) List for Appropriate DTC Table

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 ABS/TCS 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

Go to Diagnostic System Check

5 | Perform the Powertrain OBD System Check. Refer to Powertrain On Board Diagnostic (OBD) System Check in Engine Controls - 3.8L. Did the vehicle pass the OBD System Check? | -- | Go to Diagnostic Aids | Go to Powertrain On Board Diagnostic (OBD) System Check in Engine Controls - 3.8L