For 1990-2009 cars

### 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.

### DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P0571 Cruise Control Brake Switch 1 Circuit

### 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 4 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.

• | DTCs 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 Testing for Intermittent Conditions and Poor Connections .

Step | Action | Yes | No
--- | --- | --- | ---
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 | Do the stop lamps operate properly? | Go to Step 3 | Go to Symptoms - 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. Refer to Control Module References for ECM replacement, setup, and programming. Did you complete the replacement? | Go to Step 6 | --
6 |

1. Use the scan tool in order to clear the DTCs.
2. Operate the vehicle within the conditions for running the DTC.

Does the DTC reset?

Go to Step 2

System OK