Chevrolet Silverado / GMC Sierra. Service manual — part 2876

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

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.

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Transfer Case - MP 1625/1626-NQF - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &

Silverado

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.

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

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 1625/1626-NQF - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &

Silverado

(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.

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

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Transfer Case - MP 1625/1626-NQF - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &

Silverado

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

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

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Transfer Case - MP 1625/1626-NQF - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra &

Silverado