For 1990-2009 cars

### Diagnostic Instructions

• | Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.

• | Review Strategy Based Diagnosis for an overview of the diagnostic approach.

• | Diagnostic Procedure Instructions provides an overview of each diagnostic category.

### DTC Descriptor

DTC P0719 00: Brake Switch Circuit Low Voltage

### Circuit/System 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.

### 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 released, 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, 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 .

### Reference Information

#### Schematic Reference

Cruise Control Schematics

#### Connector End View Reference

Lighting Systems Connector End Views

#### Electrical Information Reference

• | Circuit Testing

• | Connector Repairs

• | Testing for Intermittent Conditions and Poor Connections

• | Wiring Repairs

#### Scan Tool Reference

Scan Tool Data List

### Circuit/System Testing

1. Ignition OFF, disconnect the harness connector at the Stop Lamp/TCC Switch.
2. Ignition ON, test for greater than 10 volts between the ignition 1 voltage circuit terminal A and ground.

⇒ | If less than the specified voltage, test the voltage circuit for an open/high resistance, or a short to ground.

3. Ignition OFF, connect the harness connector at the Stop Lamp/TCC Switch. Disconnect the harness connector C1 at the ECM.
4. Test for 10 volts between the TCC Brake Switch/Cruise Control Release Signal circuit and ground.

⇒ | If less than the specified voltage, test the signal circuit for an open/high resistance, or a short to ground. If the circuit tests normal, replace the Stop Lamp/TCC Switch.

⇒ | If at or greater than the specified voltage, replace the ECM.

### Repair Instructions

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

• | Stop Lamp Switch Replacement

• | Control Module References for ECM replacement, setup, and programming