This diagnostic test functions on the assumption that a sudden decrease in vehicle speed is caused by a brake pedal application. When the PCM 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 TCC brake switch without a transition of the stop lamp switch, the PCM sets DTC P1574.
• | 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). |
• | The vehicle speed decreases by at least 4.2 km/h (2.6 mph) within 0.25 seconds. |
• | The PCM detects a TCC brake transition. |
• | The PCM does not detect a stop lamp switch transition. |
• | The PCM sets the stop lamp switch status to released. |
• | The PCM disables the operation of the cruise control system. |
• | A history DTC will clear after 40 malfunction free warm-up cycles. |
• | The PCM receives a clear code command from the scan tool. |
Refer to Exterior Lighting Systems Description and Operation in Lighting Systems in order to avoid a misdiagnosis.
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 | |||
1 | Did you perform the Cruise Control Diagnostic System Check? | Go to Step 2 | |
2 |
Does the Stoplamp 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 | Repair the open or the high resistance in the stop lamp switch signal circuit. Refer to Circuit Testing and to Wiring Repairs in Wiring Systems. Did you complete the repair? | Go to Step 5 | -- |
5 |
Does the DTC reset? | Go to Step 2 | System OK |