Chevrolet Silverado / GMC Sierra. Service manual — part 1312

The ECM detects a low voltage signal on the TCC brake signal circuit for more than 2 seconds
when the serial data message from the BCM indicates the brakes are applied. The ECM sets the
DTC when the condition has been detected 8 out of 10 times.

P0573 00

The ECM detects a high voltage signal on the TCC brake signal circuit for more than 2 seconds
when the serial data message from the BCM indicates the brakes are released. The ECM sets the
DTC when the condition has been detected 8 out of 10 times.

Action Taken When the DTC Sets

The cruise control system becomes inoperative.

The ECM stores the DTC to memory.

The ECM will record the operating conditions at the time the diagnostic failed. The ECM
stores this information in Failure Records.

Conditions for Clearing the DTC

The condition for setting the DTC no longer exists.

A history DTC will clear once 40 malfunction-free ignition cycles have occurred.

Diagnostic Aids

Ensure all the stop lamps operate properly. Refer to Exterior Lighting Systems Description
and Operation to avoid misdiagnosis. If the vehicle stop lamps operate improperly, refer to
Symptoms - Lighting .

Reference Information

Schematic Reference

Cruise Control Schematics

Exterior Lights Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Cruise Control Description and Operation

2008 Chevrolet Silverado 1500

2008 ENGINE Cruise Control - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Testing

1. Disconnect the harness connector of the stop lamp switch.

2. Ignition ON, test for B+ between the stop lamp switch connector terminal B and ground.

If the reading is less than specified, test the supply circuit for a short to ground or an
open/high resistance.

3. Verify the BPP Circuit Signal data parameter displays released.

If the parameter displays applied, test the TCC Brake signal circuit for a short to
voltage. If the circuit tests normal, replace the ECM.

4. Connect a 3 amp fused jumper between stop lamp switch harness terminals A and B. Verify

the BPP Circuit Signal data parameter displays applied.

If the parameter displays released, test the TCC Brake Signal circuit for a short to
ground or an open/high resistance. If the circuit tests normal, replace the ECM.

5. If all circuits test normal, test or replace the stop lamp switch.

Component Testing

Stop Lamp Switch Test

1. Ignition OFF, disconnect the stop lamp switch.

2. With the brake pedal released, test for infinite resistance between terminals A and B of the

switch.

If resistance is not as specified, replace the stop lamp switch.

3. With the brake pedal released, test for less than 1.0 ohm resistance between terminals C and

D of the switch.

If resistance is not as specified, replace the stop lamp switch.

4. With the brake pedal applied, test for less than 1.0 ohm resistance between terminals A and

2008 Chevrolet Silverado 1500

2008 ENGINE Cruise Control - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado

B of the switch.

If resistance is not as specified, replace the stop lamp switch.

5. With the brake pedal applied, test for infinite resistance between terminals C and D of the

switch.

If resistance is not as specified, replace the stop lamp switch.

Repair Procedures

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Stop Lamp Switch Replacement (Non-Adjustable Pedal) or Stop Lamp Switch
Replacement (Adjustable Pedal)

Control Module References for ECM replacement, setup, and programming.

DTC P0575

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 P0575 00

Cruise Control Switch Signal Circuit

Circuit/System Description

When a cruise control function switch is activated, the body control module (BCM) detects a
predetermined voltage signal. The BCM sends a serial data message to the engine control module
(ECM) indicating the function that has been requested.

Conditions for Running the DTC

The ignition is ON.

Conditions for Setting the DTC

The ECM receives an invalid cruise control switch status serial data message from the BCM.

2008 Chevrolet Silverado 1500

2008 ENGINE Cruise Control - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado

This diagnostic runs continuously.

Action Taken When the DTC Sets

The Cruise Control System is disabled.

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.

Conditions for Clearing the DTC

The DTC becomes history when the conditions for setting the DTC are no longer present.

The history DTC clears after 40 consecutive warm-up cycles.

Reference Information

Schematic Reference

Cruise Control Schematics

Connector End View Reference

Component Connector End Views

Description and Operation

Cruise Control Description and Operation

Electrical Information Reference

Circuit Testing

Connector Repairs

Testing for Intermittent Conditions and Poor Connections

Wiring Repairs

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

2008 Chevrolet Silverado 1500

2008 ENGINE Cruise Control - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado