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Chevrolet Silverado / GMC Sierra. Manual - part 2834
DIAGNOSTIC INFORMATION AND PROCEDURES
DIAGNOSTIC CODE INDEX
DIAGNOSTIC CODE INDEX
DIAGNOSTIC STARTING POINT - TRANSFER CASE
Begin the system diagnosis with the Diagnostic System Check - Vehicle . The Diagnostic
System Check will provide the following information:
The identification of the control module or modules that command the system.
The ability of the control module or modules to communicate through the serial data circuit.
The identification of any stored diagnostic trouble codes (DTCs) and the status of the codes.
The use of the Diagnostic System Check - Vehicle will identify the correct procedure for
diagnosing the system and where the procedure is located.
DTC P2160 OR P2161
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 P2160
Vehicle Speed Sensor (VSS) 2 Circuit Low Voltage
DTC P2161
Vehicle Speed Sensor (VSS) 2 Circuit Intermittent
Diagnostic Fault Information
DTC
Description
DTC P2160 or P2161
P2160: Vehicle Speed Sensor (VSS) 2 Circuit Low Voltage
P2161: Vehicle Speed Sensor (VSS) 2 Circuit Intermittent
2008 Chevrolet Silverado 1500
2008 TRANSMISSION Transfer Case - MP 1222/1225/1226-NQG - Cab & Chassis Sierra, Cab & Chassis Silverado,
Sierra & Silverado
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.
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.
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 1222/1225/1226-NQG - Cab & Chassis Sierra, Cab & Chassis Silverado,
Sierra & Silverado
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
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
2008 Chevrolet Silverado 1500
2008 TRANSMISSION Transfer Case - MP 1222/1225/1226-NQG - Cab & Chassis Sierra, Cab & Chassis Silverado,
Sierra & Silverado
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
Circuit/System Verification
1. Raise and support the drive wheels.
2. Start and idle the engine.
3. Place the transmission in DRIVE.
4. Monitor VSS on the scan tool under engine data.
5. The VSS on the scan tool should be greater than 100 RPM.
Circuit/System Testing
1. Measure the resistance between the VSS high signal circuit and the VSS low signal circuit.
The resistance should be between 1,420-2,140 ohms.
If the value is greater than 2,140 ohms, test the VSS high signal circuit and the VSS
low signal circuit for an open.
2008 Chevrolet Silverado 1500
2008 TRANSMISSION Transfer Case - MP 1222/1225/1226-NQG - Cab & Chassis Sierra, Cab & Chassis Silverado,
Sierra & Silverado
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