Content .. 2511 2512 2513 2514 ..
Chevrolet Silverado / GMC Sierra. Manual - part 2513
DIAGNOSTIC CODE INDEX
DTC P0502 OR P0503
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 P0502
Vehicle Speed Sensor (VSS) Circuit Low Voltage
DTC P0503
Vehicle Speed Sensor (VSS) Circuit Intermittent
Diagnostic Fault Information
Circuit/System Description
DTC
Description
DTC P0502 or P0503
P0502: Vehicle Speed Sensor (VSS) Circuit Low Voltage
P0503: Vehicle Speed Sensor (VSS) Circuit Intermittent
DTC P0806
P0806: Clutch Pedal Position (CPP) Sensor Circuit
Performance
DTC P0807 or P0808
P0807: Clutch Pedal Position (CPP) Sensor Circuit Low
Voltage
P0808: Clutch Pedal Position (CPP) Sensor Circuit High
Voltage
DTC P080A
P080A: Clutch Pedal Position (CPP) Not Learned
Circuit
Short to
Ground
Open/High
Resistance
Short to
Voltage
Signal
Performance
VSS Low Signal
-
P0502, P0503
-
-
VSS High Signal
P0502,
P0503
P0502, P0503
P0502,
P0503
-
2008 Chevrolet Silverado 1500
2008 TRANSMISSION Manual Transmission - Tremec 5-Speed (M96) - Cab & Chassis Sierra, Cab & Chassis
Silverado, Sierra & Silverado
The vehicle speed information is provided to the engine control module (ECM) by the vehicle
speed sensor (VSS). The VSS is a permanent magnet generator that is mounted to the
transmission and produces a pulsing voltage. The AC voltage amplitude and frequency increases
with vehicle speed. The ECM converts the pulsing voltage into km/h (mph). The ECM supplies
the VSS signal to the following components:
The instrument panel for speedometer and odometer operation
The cruise control module
Conditions for Running the DTC
P0502
DTC P0120, P0220 or P0503 are not set.
The TP sensor angle is more than 3.5 percent.
The engine is running.
The system voltage is 8-18V.
TFT is more than -40°C (-40°F)
The engine speed is 1,500-6,500 RPM.
Vehicle speed is less than 200 km/h (124 mph).
Engine torque is 68-8,192 N.m (50-6,042 lb ft).
The PTO is not active.
P0503
The system voltage is 8-18V.
The engine speed is 500-7,500 RPM.
Transmission out speed change is less than 146 RPM for 2 seconds.
The PTO is not active.
The OSS is at least 292 RPM for 2 seconds.
The OSS has not changed more than 146 RPM for 2 seconds.
The 4WD range has not changed within 6 seconds.
Conditions for Setting the DTC
P0502
The transmission output speed is 58 RPM or less for 5 seconds.
2008 Chevrolet Silverado 1500
2008 TRANSMISSION Manual Transmission - Tremec 5-Speed (M96) - Cab & Chassis Sierra, Cab & Chassis
Silverado, Sierra & Silverado
P0503
The transmission output speed drops 351 RPMs in less than 3 seconds.
Action Taken When the DTC Sets
P0502 and P0503 are Type B DTCs.
Conditions for Clearing the DTC
P0502 and P0503 are Type B DTCs.
Reference Information
Schematic Reference
PSD SIE TITLE Error: SIE linked to empty Cell ID 168122
Connector End View Reference
Component Connector End Views
Description and Operation
Manual Transmission 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
Special Tools
2008 Chevrolet Silverado 1500
2008 TRANSMISSION Manual Transmission - Tremec 5-Speed (M96) - Cab & Chassis Sierra, Cab & Chassis
Silverado, Sierra & Silverado
J 35616 GM-Approved Terminal Test Kit
Circuit/System Verification
1. Raise and support the drive wheels.
2. Start and idle the engine.
3. Place the transmission in second gear and release the clutch pedal.
4. Monitor VSS parameter on the scan tool. The VSS parameter should increase as the drive
wheel speed increases.
5. Operate the vehicle within the conditions for running the DTC. You may also operate the
vehicle within the conditions that are captured in the Freeze Frame/Failure Records List.
Circuit/System Testing
1. Disconnect the ECM harness connector X1.
2. Measure for 1,300-1,500 ohms at 25°C (77°F) between the VSS high signal circuit terminal
71 and the VSS low signal circuit terminal 72.
If the value is greater than 1,500 ohms test the VSS high signal circuit and the VSS
low signal circuit for an open/high resistance. If the circuits/connections test normal,
replace the vehicle speed sensor.
If the value is less than 1,300 ohms test the VSS high signal and the VSS low signal
circuits for a shorted together condition. If the circuits/connections test normal, replace
the vehicle speed sensor.
3. Measure for more than 10 ohms of resistance between the VSS high signal circuit terminal
71 and ground.
If the value is less than the specified range, repair the short to ground.
4. Measure for more than 10 ohms of resistance between the VSS low signal circuit terminal
72 and ground.
If the value is less than the specified range, repair the short to ground.
5. Reconnect the ECM connector. Disconnect the VSS connector.
6. Ignition ON, test the VSS high signal circuit terminal B for a short to voltage.
If all circuits/connections test normal, test or replace the VSS.
Repair Procedures
Perform the Diagnostic Repair Verification after completing the repair.
Vehicle Speed Sensor Replacement
2008 Chevrolet Silverado 1500
2008 TRANSMISSION Manual Transmission - Tremec 5-Speed (M96) - Cab & Chassis Sierra, Cab & Chassis
Silverado, Sierra & Silverado
Content .. 2511 2512 2513 2514 ..