Content .. 2921 2922 2923 2924 ..
Chevrolet Silverado / GMC Sierra. Manual - part 2923
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
Perform the motor learn procedure before normal operation will occur.
Circuit/System Testing
1. If the voltage is low check the voltage on other vehicle systems to determine if this is a
vehicle wide condition and take appropriate actions. If this is transfer case specific check
the ignition 3 feed to the transfer case control module and the ground for the transfer case
control module for proper connections.
2. If the voltage is high, this is likely a vehicle issue such as an alternator problem or the
vehicle has been hooked up improperly during a jump start.
3. After the condition is corrected perform the motor learn procedure.
Repair Procedures
Perform the Diagnostic Repair Verification after completing the diagnostic procedure.
Transfer Case High/Low Clutch Reset
DTC P2160 OR P2161
Diagnostic Instructions
Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
2008 Chevrolet Silverado 1500
2008 TRANSMISSION Transfer Case - MP 3023/3024-NQH - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
Review Strategy Based Diagnosis for an overview of the diagnostic approach.
Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptor
DTC P2160
Vehicle Speed Sensor (VSS) 2 Circuit Low Voltage
DTC P2161
Vehicle Speed Sensor (VSS) 2 Circuit Intermittent
Diagnostic Fault Information
Circuit/System Description
The vehicle speed sensor (VSS) provides vehicle speed information to the engine control module
(ECM). The VSS is a permanent magnet generator. The sensor is mounted in the transfer case
facing the rear internal gear which is splined to the output shaft assembly. As the output shaft and
internal gear rotate, the toothed rotor of the internal gear produces AC voltage as the rotor teeth
pass through the magnetic field of the sensor. The AC voltage level and the number of pulses
increase as the speed of the vehicle increases. The ECM converts the voltage to vehicle speed.
The ECM uses the output shaft speed signal to determine shift timing and torque converter clutch
(TCC) scheduling, as well as transfer case range.
Conditions for Running the DTC
P2160
No input speed sensor (ISS) DTCs P0716 or P0717.
No OSS DTCs P0722 or P0723.
No transmission fluid pressure (TFP) DTCs P1810, P1815, P1816, or P1818.
Circuit
Short to
Ground
Open/High
Resistance
Short to
Voltage
Signal
Performance
VSS Supply Voltage
P2160,
P2161
P2160, P2161
P2160,
P2161
P2161
VSS Signal
P2160,
P2161
P2160, P2161
P2160,
P2161
P2161
2008 Chevrolet Silverado 1500
2008 TRANSMISSION Transfer Case - MP 3023/3024-NQH - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
The transmission is not in PARK or NEUTRAL.
Transmission fluid temperature (TFT) is between -40° to +150°C (-40° to +302°F).
The throttle position is 8 percent or greater.
The engine torque is greater than 50 N.m (37 lb ft).
The input speed is greater than 1,500 RPM.
The TCC slip speed is at least -20 RPM.
P2161
No 1-2 Shift Solenoid Electrical DTC P0974.
No ISS DTCs P0716 or P0717.
The transmission is not in PARK or NEUTRAL.
The transmission output speed is greater than 1,400 RPM for 2 seconds or greater.
One of the following conditions exist:
The transmission input shaft speed has changed less than 500 RPM for at least 2
seconds.
The transmission output shaft speed has not increased at least 500 RPM for at least 2
seconds.
Conditions for Setting the DTC
P2160
The transfer case output shaft speed is 50 RPM or less for 4.5 seconds.
P2161
The transfer case output shaft speed drops 1,200 RPM or greater for at least 3.25 seconds.
Action Taken When the DTC Sets
DTCs P2160 and P2161 are Type B DTCs.
The TCM commands maximum line pressure.
The TCM freezes transmission adaptive functions.
The TCM calculates vehicle speed from the automatic transmission input shaft speed sensor
and commanded gear.
Conditions for Clearing the DTC
2008 Chevrolet Silverado 1500
2008 TRANSMISSION Transfer Case - MP 3023/3024-NQH - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
DTCs P2160 and P2161 are Type B DTCs.
Diagnostic Aids
Inspect the rear internal gear teeth for damage.
Visually inspect the VSS for cracks or damage.
Ensure the VSS is properly torqued to the transfer case housing.
This diagnostic relates to the VSS located in the transfer case and not the OSS located
within the transmission.
Reference Information
Schematic Reference
Transfer Case Control Schematics
Engine Controls Schematics
Connector End View Reference
Component Connector End Views
Description and Operation
Transfer Case Description and Operation
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
2008 Chevrolet Silverado 1500
2008 TRANSMISSION Transfer Case - MP 3023/3024-NQH - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &
Silverado
Content .. 2921 2922 2923 2924 ..