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Chevrolet Silverado / GMC Sierra. Manual - part 2921
DTC C0398
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 C0398 5A
Incremental Sensor - Rotational Position Sensor Correlation Plausibility Failure
Diagnostic Fault Information
Circuit/System Description
The transfer case incremental position sensor and the rotational position sensor are both input to
the transfer case control module as to the range or mode the transfer case is in. Both sensors are
capable of showing position by degrees. If the two sensors disagree by 5 percent or more this
DTC will set.
Conditions for Running the DTC
The ignition is ON.
System voltage is 10.5-18 volts.
Conditions for Setting the DTC
Both sensors must be showing a valid position at the time the DTC is set.
Action Taken When the DTC Sets
Shifting is still disabled until the DTC has cleared itself.
Circuit
Short to
Ground
Open/High
Resistance
Short to
Voltage
Actuator
Plausibility
Failure
Incremental Sensor -
Rotational Position Sensor
Correlation Plausibility
-
-
-
DTC C0398
5A
2008 Chevrolet Silverado 1500
2008 TRANSMISSION Transfer Case - MP 3023/3024-NQH - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
The SERVICE 4WD indicator remains illuminated for the remainder of the current ignition
cycle.
Conditions for Clearing the DTC
The transfer case shift control module clears the DTC if the condition for setting the DTC is
not currently present.
A history DTC clears after 40 consecutive warm up cycles without a fault present.
History DTCs can be cleared using a scan tool.
Reference Information
Schematic Reference
Transfer Case Control Schematics
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
Scan Tool Data List
Scan Tool Data Definitions
Diagnostic Aids
Each of the two sensors show the transfer case movement in degrees. Find the sensor either the
incremental sensor or the RPS that seems to not be showing a reading in degrees and is doing so
erratically this is probably the sensor causing the DTC.
Circuit/System Testing
Inspect the RPS sensor for damage at the mating surface with the rotational position shaft.
2008 Chevrolet Silverado 1500
2008 TRANSMISSION Transfer Case - MP 3023/3024-NQH - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
1. If the RPS sensor shows damage at the mating surface then replace the RPS sensor. If no
damage is found attempt to turn the shaft while the transfer case in stationary in one mode.
2. If the shaft can be turned then internal damage has occurred to this shaft, refer to transfer
case disassemble and inspection and repair as necessary. If no damage is found and the RPS
sensor seems to show a steady degrees rotation reading on the scan tool data list then replace
the transfer case two/four wheel drive actuator.
Repair Procedures
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Transfer Case Disassemble
Transfer Case Two/Four Wheel Drive Actuator Replacement
Transfer Case Two/Four Wheel Drive Actuator Position Sensor Replacement
DTC C0550
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 C0550 37
Electronic Control Unit Malfunction Watchdog/Safety Failure
DTC C0550 39
Electronic Control Unit Malfunction Internal Electronic Failure
Diagnostic Fault Information
Circuit
Short to
Ground
Open/High
Resistance
Watchdog/Safety
Failure
Internal
Electronic
Failure
Electronic Control Unit
Malfunction
-
-
DTC C0550 39
DTC C0550
39
2008 Chevrolet Silverado 1500
2008 TRANSMISSION Transfer Case - MP 3023/3024-NQH - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
Circuit/System Description
This DTC indicates and RAM/ROM checksum, a EEPROM failure, or an ECU malfunction due
to an internal microprocessor failure.
Conditions for Running the DTC
The ignition is ON.
System voltage is 10.5-18 volts.
Conditions for Setting the DTC
The EEPROM, RAM and ROM, and ECM Microprocessor do self checks against one another
and the data does not match causing the DTC to set.
Action Taken When the DTC Sets
Shifting is still disabled until the DTC has cleared itself.
The SERVICE 4WD indicator remains illuminated for the remainder of the current ignition
cycle.
Conditions for Clearing the DTC
The transfer case shift control module clears the DTC if the condition for setting the DTC is
not currently present.
A history DTC clears after 40 consecutive warm up cycles without a fault present.
History DTCs can be cleared using a scan tool.
Reference Information
Schematic Reference
Transfer Case Control Schematics
Connector End View Reference
Component Connector End Views
Electrical Information Reference
Circuit Testing
Connector Repairs
2008 Chevrolet Silverado 1500
2008 TRANSMISSION Transfer Case - MP 3023/3024-NQH - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
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