Circuit Description
The cruise release switch is a normally closed switch. The stop lamp switch signal circuit is a normally open switch. When the brake pedal is released, the engine control module (ECM) detects a high voltage signal on the torque converter clutch (TCC) brake switch/cruise control release signal circuit and a low signal voltage signal on the stop lamp switch signal circuit.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P1574 Stoplamp Switch Circuit
Conditions for Running the DTC
| • | The engine is ON. |
| • | The traction control system or the antilock brake system are not active and have not failed. |
| • | The vehicle has accelerated from 0 km/h (0 mph) to 60 km/h (37 mph) 3 times in one ignition cycle. |
| • | This diagnostic runs continuously once the conditions for running the DTC has been achieved. |
Conditions for Setting the DTC
When the brake pedal is pressed, the ECM detects a low voltage signal on the stop lamp switch signal circuit and a low voltage signal on the TCC brake switch/cruise control release signal circuit.
Action Taken When the DTC Sets
| • | The ECM stores the DTC information into memory when the diagnostic runs and fails. |
| • | The malfunction indicator lamp (MIL) will not illuminate. |
| • | The ECM records the operating conditions at the time the diagnostic fails. The ECM stores this information in the Failure Records. |
| • | The Cruise Control System is disabled. |
Conditions for Clearing the DTC
| • | A last test failed, or current DTC, clears when the diagnostic runs and does not fail. |
| • | A history DTC will clear after 40 consecutive warm-up cycles, if no failures are reported by this or any other non-emission related diagnostic. |
| • | Use a scan tool in order to clear the DTC. |
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 . |
| • | Inspect for proper adjustment of the stop lamps. Refer to Stop Lamp Switch Adjustment . |
| • | For an intermittent condition, refer to Testing for Intermittent Conditions and Poor Connections . |
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Cruise Control Schematics Connector End View Reference: Lighting Systems Connector End Views | |||
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | |
2 | Do the stop lamps work properly? | Go to Step 3 | Go to Stop Lamps Inoperative |
3 | Test the stop lamp switch signal circuit for an open or for a high resistance between the body control module (BCM) and the engine control module (ECM). Refer to Circuit Testing and Wiring Repairs . 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. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 6 | Go to Step 5 |
5 | Replace the ECM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | Go to Step 6 | -- |
6 |
Does the DTC reset? | Go to Step 2 | System OK |
