Circuit Description
This DTC is used in order to identify open stoplamp switch circuitry that prevents the stoplamp switch input from changing states when the brake is applied. This DTC is used in conjunction with DTC C1291 in order to determine the cause of an open stoplamp switch malfunction.
Conditions for Running the DTC
The ignition is ON.
Conditions for Setting the DTC
The stop lamp switch input voltage is between 2.1 volts and 5.3 volts for 2 seconds.
Action Taken When the DTC Sets
| • | The EBCM disables the TCS for the duration of the ignition cycle. |
| • | The TRACTION OFF indicator turns ON. |
| • | The ABS remains functional. |
Conditions for Clearing the DTC
| • | The condition for the DTC is no longer present and the DTC is cleared with a scan tool. |
| • | The electronic brake control module (EBCM) automatically clears the history DTC when a current DTC is not detected in 100 consecutive drive cycles. |
Diagnostic Aids
Possible causes of this DTC are the following conditions:
| • | A signal circuit of the stop lamp switch is open. |
| • | The stop lamp switch is misadjusted. |
| • | Verify proper stop lamp switch operation using the data list of the scan tool. As the brake is applied, the data list displays the stop lamp switch ON within 2.54 cm (1 in) of travel. |
| • | All brake lamps are open. |
| • | All brake lamp grounds are open. |
| • | Circuit has a wiring problem, terminal corrosion, or poor connections. |
| • | Loose or corroded EBCM ground or ECM ground. |
| • | An internal EBCM problem. |
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This DTC detects an open stoplamp switch signal circuit from the stoplamp side of the splice pack to the EBCM.
-
The EBCM sources 5 volts on the stoplamp switch signal circuit. This small voltage has a ground path through the stoplamp bulbs. This DTC sets if the path to ground is open.
Step | Action | Value(s) | Yes | No | ||||||
|---|---|---|---|---|---|---|---|---|---|---|
1 | Did you perform the ABS Diagnostic System Check? | -- | Go to Step 2 | |||||||
2 |
Does the Brake Switch - ABS Input parameter display Applied? | -- | Go to Step 4 | Go to Step 3 | ||||||
Test the signal circuit of the stoplamp/auto trans shift lock control switch for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 9 | Go to Step 7 | |||||||
Press the brake pedal. Are all of the stoplamps OFF? | -- | Go to Step 5 | Go to Diagnostic Aids | |||||||
5 | Test the feed circuit of the stoplamps for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 9 | Go to Step 6 | ||||||
6 | Test the ground circuit for the stoplamps for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 9 | Go to Diagnostic Aids | ||||||
7 | Inspect for poor connections at the harness connector of the EBCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | -- | Go to Step 9 | Go to Step 8 | ||||||
8 |
Important: Perform the setup procedure for the EBCM. An unprogrammed EBCM will
result in the following conditions:
Replace the EBCM. Refer to Electronic Brake Control Module Replacement . Did you complete the replacement? | -- | Go to Step 9 | -- | ||||||
9 |
Does the DTC reset? | -- | Go to Step 2 | System OK |
