Circuit Description
The stop lamp switch signal circuit is a direct hardwire input to the engine control module (ECM) from the brake switch assembly. The ECM monitors the stop lamp switch signal circuit in order to detect when the brake pedal has been applied.
Conditions for Setting the DTC
The engine is running.
Action Taken When the DTC Sets
| • | The malfunction indicator lamp (MIL) will illuminate. |
| • | No VSS No signal diagnostic fail. |
| • | Cruise vehicle speed filter is greater than 20 km/h. |
| • | The ECM will record operating conditions at the time the diagnostic fail. This information will be stored in the Freeze Frame and Failure Records buffers. |
| • | A history DTC is stored. |
Conditions for Clearing the MIL/DTC
| • | The MIL will turn off after four consecutive validation cycle in which the diagnostic runs without a fault. |
| • | A history DTC will clear after 40 consecutive warm up cycles without a fault. |
| • | DTC(s) can be cleared by using the scan tool. |
Diagnostic Aids
In order to avoid a misdiagnosis, inspect for proper operation of the stop lamps.
For an intermittent condition, refer to Intermittents.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |
2 | Do the stop lamps operate properly? | -- | Go to Step 3 | Go to Lighting Systems |
3 | Test the stop lamp switch signal circuit for an open or for a high resistance between the brake switch and the engine control module (ECM). Did you find and correct the condition? | -- | Go to Step 6 | Go to Step 4 |
4 | Inspect for poor connections at the harness connector of the ECM. Did you find and correct the condition? | -- | Go to Step 6 | Go to Step 5 |
5 | Replace the ECM. Did you complete the replacement? | -- | Go to Step 6 | -- |
6 |
Does the DTC reset? | -- | Go to Step 2 | System OK |
