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Chevrolet Silverado / GMC Sierra. Manual - part 2792
Description and Operation
Trailer Brake Controls Description and Operation
Connector End View Reference
Component Connector End Views
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
Diagnostic Aids
If there are any other DTCs set for GMLAN communication such as U0100, U0121, U0140, or
U2099, diagnose them first before to resolve DTCs described in this section.
C0800 03
Test the charging system Refer to Diagnostic System Check - Vehicle .
Possible causes of this DTC are the following conditions:
A charging system malfunction
An excessive battery draw
A weak battery
A faulty system ground
C0800 07
Test the charging system Refer to Diagnostic System Check - Vehicle .
A possible cause of this DTC is overcharging.
Circuit/System Verification
2008 Chevrolet Silverado 1500
2008 BRAKES Trailer Brake Controls - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado
With the scan tool installed, ignition ON and the engine running, observe the Battery Positive
Voltage parameter in the TBCM data list. The reading should be between 9-17 volts.
Circuit/System Testing
1. If the DTC is history, refer to Charging System Test .
2. If the DTC is current, start the engine, and measure the voltage between the battery positive
voltage circuits of the TBCM and the ground circuit.
If the voltage is within 9-17 volts, replace the affected module.
If the voltage is not within 9-17 volts, measure the voltage between the battery positive
voltage circuits of the TBCM and a separate good ground.
If the voltage is within 9-17 volts, test the battery positive ground circuits of the
TBCM for high resistance or an open, and repair as necessary.
Repair Procedures
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for TBCM replacement, setup, and programming
DTC C0845
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 C0845 03
Device Ignition 1 Circuit Voltage Below Threshold
Diagnostic Fault Information
Circuit
Short to
Ground
High
Resistance
Open
Short to
Voltage
Signal
Performance
Ignition 1 Circuit
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-
C0845 03
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-
TCC Brake Signal Circuit
C0845 03
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-
-
-
2008 Chevrolet Silverado 1500
2008 BRAKES Trailer Brake Controls - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado
Circuit/System Description
The trailer brake control module (TBCM) checks whether there is an ignition ground short fault.
This diagnostic compares ignition state with the engine running state received over serial data to
determine whether or not there is an ignition ground short fault.
Conditions for Running the DTC
The engine is running.
Conditions for Setting the DTC
The engine is running, and the TBCM detects that the IGN 1 voltage is less than 9.2 volts
Action Taken When the DTC Sets
The trailer brake control will be disabled for the remainder of the ignition cycle.
The Service Trailer Brake System will be displayed on the Driver Information Center
(DIC).
Conditions for Clearing the MIL/DTC
When the condition for the DTC is no longer present.
The TBCM automatically clears the history DTC when a current DTC is not detected in 40
consecutive drive cycles.
Diagnostic Aids
If there are any other DTCs set for GMLAN communication such as U0100, U0121, U0140, or
U2099, diagnose them first before resolving DTCs described in this section.
Reference Information
Schematic Reference
Trailer Brake Control Schematics
Description and Operation
Trailer Brake Controls Description and Operation
IMPORTANT: The ignition may need to be cycled twice, waiting 30 seconds
between key cycles, to move the code from current to history
2008 Chevrolet Silverado 1500
2008 BRAKES Trailer Brake Controls - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado
Connector End View Reference
Component Connector End Views
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. Ignition OFF, disconnect the harness connector of the TBCM.
2. Ignition ON, test for 11 volts or greater between the IGN 1 voltage circuit terminal 15 and
ground.
If less than the specified voltage, test the IGN 1 voltage circuit for a short to ground or
an open/high resistance. If the circuit test normal and the MISC - IGN fuse 44 is open,
test the voltage circuit for a short to ground. If the circuit tests normal, test or replace
the RUN/CRANK relay.
3. If all circuits test normal, and the DTC resets as current, replace the TBCM.
Repair Procedures
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for TBCM replacement, setup, and programming
DTC C0870
Diagnostic Instructions
IMPORTANT: Verify that stop lamp DTCs are not set as current or history
before performing this diagnostic. If stop lamp DTCs are set as
current or history, go to lighting for diagnose.
2008 Chevrolet Silverado 1500
2008 BRAKES Trailer Brake Controls - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado
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