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Chevrolet Silverado / GMC Sierra. Manual - part 2794
Scan Tool Reference
Control Module References for Scan Tool Information
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the trailer brake controller switch panel.
2. Test for less than 5 ohms of resistance between the ground circuit terminal 8 and ground.
If greater than the specified range, test the ground circuit for an open/high resistance.
If the circuit tests normal, replace the TBCM.
3. Ignition ON, test for 4.8 - 5.2 volts between the 5-volt reference circuit terminal 6 and
ground.
If less than the specified range, test the 5-volt reference circuit for a short to ground or
an open/high resistance. If the circuit tests normal, replace the TBCM.
If greater than the specified range, test the 5-volt reference circuit for a short to
voltage. If the circuit tests normal, replace the TBCM.
4. If all circuits test normal, test or replace the trailer brake controller switch panel.
Repair Procedures
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for TBCM replacement, setup, and programming
DTC C0890
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 C0890
Device Voltage Reference Output 3 Circuit
IMPORTANT: All electrical components and accessories must be turned OFF
and allowed to power down.
2008 Chevrolet Silverado 1500
2008 BRAKES Trailer Brake Controls - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado
Diagnostic Fault Information
Circuit/System Description
The TBCM runs this diagnostics to check whether there is a fault on the internal TBCM 5 volt
references used to monitor the Manual Apply switch circuits. This diagnostics checks if the
circuits 5 volt references is within a range for normal operation.
Conditions for Running the DTC
The system voltage is in the range of 9.5 - 17 volts.
The module initialization has taken place.
Conditions for Setting the DTC
The TBCM detects voltage greater than 5.2 volts in the manual apply switch 5 volt reference
circuit.
The TBCM detects voltage less than 4.8 volts in the manual apply switch 5 volt reference circuit.
Action Taken When the DTC Sets
The trailer brake control will be disabled at the end of the current brake apply for the
remainder of the ignition cycle.
A message center or an indicator displays.
Conditions for Clearing the 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 DTCs set for GMLAN communication such as U0100, U0121, U0140, or U2099
or the antilock brake control system, diagnose them first before to resolve DTCs described in this
section.
Circuit
Short to
Ground
High
Resistance
Open
Short to
Voltage
Signal
Performance
Device Voltage Reference
Output 3 Circuit
C0890
-
-
C0890
-
2008 Chevrolet Silverado 1500
2008 BRAKES Trailer Brake Controls - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado
Reference Information
Schematic Reference
Trailer Brake Control Schematics
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
DTC Type Reference
Powertrain Diagnostic Trouble Code (DTC) Type Definitions
Scan Tool Reference
Control Module References for scan tool information.
Circuit/System Testing
1. Ignition OFF, disconnect the harness connector at the trailer brake controller switch panel.
2. Test for less than 5 ohms of resistance between the ground circuit terminal 5 and ground.
If greater than the specified range, test the ground circuit for an open/high resistance.
If the circuit tests normal, replace the TBCM.
3. Ignition ON, test for 4.8 - 5.2 volts between the 5-volt reference circuit terminal 3 and
ground.
IMPORTANT: All electrical components and accessories must be turned OFF
and allowed to power down.
2008 Chevrolet Silverado 1500
2008 BRAKES Trailer Brake Controls - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado
If less than the specified range, test the 5-volt reference circuit for a short to ground or
an open/high resistance. If the circuit tests normal, replace the TBCM.
If greater than the specified range, test the 5-volt reference circuit for a short to
voltage. If the circuit tests normal, replace the TBCM.
4. If all circuits test normal, test or replace the trailer brake controller switch panel.
Repair Procedures
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Control Module References for TBCM replacement, setup, and programming
DTC C1112
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 C1112
Trailer Brake Control Relay Low Control Circuit - Relay Control Active Low
Diagnostic Fault Information
Circuit/System Description
The trailer brake control module (TBCM) diagnostic monitor detects faults on the solid state
relay (SSR) relay control active low circuit.
Circuit
Short to
Ground
High
Resistance
Open
Short to
Voltage
Signal
Performance
Relay Control Active Low
Circuit
C1112
-
C1112
C1112
-
TBCM Relay Control Circuit
C1112
-
C1112
C1112
-
SSR Fuse STUD 2 Power
Circuit
-
-
C1112
-
-
2008 Chevrolet Silverado 1500
2008 BRAKES Trailer Brake Controls - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado
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