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Chevrolet Silverado / GMC Sierra. Manual - part 1311
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
A last test failed, or the current DTC, clears when the diagnostic runs and does not fail.
A history DTC clears after 40 consecutive warm-up cycles, if failures are not reported by
this or any other emission related diagnostic.
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
Electrical Information Reference
Circuit Testing
Connector Repairs
Testing for Intermittent Conditions and Poor Connections
Wiring Repairs
Scan Tool Reference
2008 Chevrolet Silverado 1500
2008 ENGINE Cruise Control - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado
Control Module References for scan tool information
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector of the stop lamp switch.
2. Ignition ON, verify that a test lamp illuminates between the stop lamp switch voltage circuit
terminal B and ground.
If the test lamp does not illuminate, test the stop lamp switch voltage circuit for a short
to ground or an open/high resistance. If the circuit tests normal, test or replace the
RUN/CRANK Relay.
3. Ignition OFF, disconnect the harness connectors of the BCM X5, ECM X1, TCM (if
equipped), Power Take Off (PTO) module (if equipped) and Trailer Brake controller (if
equipped).
4. Ignition OFF, verify that a test lamp does not illuminate between the stop lamp switch
harness terminal A and B+.
If the test lamp illuminates, test the brake switch signal circuit for a short to ground.
5. Test for less than 1.0 ohm resistance between the stop lamp switch harness terminal A and
one of the following:
ECM connector X1 terminal 83 for the 6.6L engine.
ECM connector X1 terminal 55 for the 4.3L engine.
ECM connector X1 terminal 9 for the 4.8L, 5.3L, 6.0L, 6.2L or 7.0L engines.
If resistance is not as specified, test the stop lamp switch circuit for an open/high
resistance.
6. Ignition ON, verify that a test lamp does not illuminate between the stop lamp switch TCC
brake signal circuit terminal A and ground.
If the test lamp illuminates, test the brake switch signal circuit for a short to voltage.
7. If all circuits test normal, test or replace the stop lamp switch. If the component and all
circuit tests are normal, replace the ECM.
Component Testing
Relay Test
1. Ignition OFF, disconnect the RUN/CRANK relay.
2. Test for 60-180 ohms of resistance between terminals 85 and 86.
If the resistance is not within the specified range, replace the relay.
3. Test for infinite resistance between the following terminals:
2008 Chevrolet Silverado 1500
2008 ENGINE Cruise Control - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado
30 and 86
30 and 87
30 and 85
85 and 87
If less than infinite resistance, replace the RUN/CRANK relay.
4. Install a 20-amp fused jumper wire between relay terminal 85 and 12 volts. Install a jumper
wire between relay terminal 86 and ground. Test for less than 2.0 ohms of resistance
between terminals 30 and 87.
If greater than 2.0 ohms, replace the RUN/CRANK relay.
Switch Test
1. Ignition OFF, disconnect the stop lamp switch.
2. With the brake pedal released, measure for infinite resistance between terminals A and B of
the switch.
If resistance is measured, replace the switch.
3. With the brake pedal released, measure for less than 1.0 ohm resistance between terminals C
and D of the switch.
If resistance is not as specified, replace the switch.
4. With the brake pedal applied, measure for less than 1.0 ohm resistance between terminals A
and B of the switch.
If resistance is not as specified, replace the switch.
5. With the brake pedal applied, measure for infinite resistance between terminals C and D of
the switch.
If resistance is measured, replace the 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 P0572 OR P0573
Diagnostic Instructions
2008 Chevrolet Silverado 1500
2008 ENGINE Cruise Control - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado
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 P0572 00
Brake Switch Circuit 1 Low Voltage
DTC P0573 00
Brake Switch Circuit 1High Voltage
Diagnostic Fault Information
Circuit/System Description
The TCC Brake signal circuit is a high voltage input to the body control module (BCM), engine
control module (ECM), transmission control module (TCM), Power Take Off (PTO) module (if
equipped) and Trailer Brake controller (if equipped). The BCM monitors the stop lamp switch
circuit to detect when the brake pedal has been applied. The ECM monitors the TCC Brake
signal to determine when the brake pedal is applied. When the brake pedal is applied, the BCM
sends a serial data message to the ECM indicating that the brake pedal has been applied. The
ECM senses a high voltage signal on the brake switch signal circuit when the stop lamp switch is
closed.
Conditions for Running the DTC
The engine is running.
Battery voltage is greater than 11.5 volts.
Conditions for Setting the DTC
P0572 00
Circuit
Short to
Ground
Open or High
Resistance
Short to
Voltage
Signal
Performance
Ignition 1 Voltage
P0572 00
P0572 00
-
-
TCC Brake Signal
P0572 00
P0572 00
P0573 00
-
2008 Chevrolet Silverado 1500
2008 ENGINE Cruise Control - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado
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