Circuit Description
This diagnostic test functions on the assumption that a sudden decrease in vehicle speed is caused by a brake pedal application. When the ECM detects that there is a 4.2 km/h (2.6 mph) or greater decrease in vehicle speed within 0.25 seconds and a transition of the cruise release switch without a transition of the stop lamp switch, the ECM sets DTC P1574.
Conditions for Running the DTC
| • | DTCs P0502, P0503, P0719, and P0724 are not set. |
| • | The engine speed is greater than 700 RPM. |
| • | The traction control system or the antilock brake system are not active and have not failed. |
| • | The vehicle speed is greater than 48 km/h (30 mph) in order to enable the diagnostic. |
| The diagnostic will disable when the wheel speed is less than 16 km/h (10 mph). |
Conditions for Setting the DTC
| • | The vehicle speed decreases by at least 4.2 km/h (2.6 mph) within 0.25 seconds. |
| • | The ECM detects a cruiserelease switch transition. |
| • | The ECM does not detect a stop lamp switch transition. |
Action Taken When the DTC Sets
| • | The ECM sets the stop lamp switch status to released. |
| • | The ECM disables the operation of the cruise control system. |
Conditions for Clearing the DTC
| • | A history DTC will clear after 40 malfunction free warm-up cycles. |
| • | The ECM receives a clear code command from the scan tool. |
Diagnostic Aids
In order to avoid a misdiagnosis, perform the following:
| • | Inspect for proper operation of the stop lamps. Refer to Exterior Lighting Systems Description and Operation in Lighting Systems. |
| • | Inspect for proper adjustment of the stop lamps. Refer to Stop Lamp Switch Adjustment in Lighting Systems. |
| • | Inspect for proper adjustment of the cruise control release switch. Refer to Cruise Release Switch Adjustment . |
| • | For an intermittent condition, refer to Testing for Intermittent Conditions and Poor Connections in Wiring Systems. |
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference : Cruise Control Schematics Connector End View Reference: Cruise Control Connector End Views or Lighting Systems Connector End Views in Lighting Systems | |||
1 | Did you perform the Cruise Control Diagnostic System Check? | Go to Step 2 | |
2 |
Does the Brake Pedal Switch parameter display Released? | Go to Step 3 | Go to Diagnostic Aids |
3 | Do the stop lamps operate properly? | Go to Step 4 | Go to Stop Lamps Inoperative in Lighting Systems |
4 | Test the stop lamp switch signal circuit for an open or for a high resistance. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 7 | Go to Step 5 |
5 | Inspect for poor connections at the harness connector of the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and to Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 7 | Go to Step 6 |
6 |
Important: Program the replacement ECM. Replace the ECM. Refer to Engine Control Module Replacement in Engine Controls-2.2 L. Did you complete the replacement? | Go to Step 7 | -- |
7 |
Does the DTC reset? | Go to Step 2 | System OK |
