2010 Cadillac CTS Sedan AWD V6-3.6L Page 1473
Repair Instructions
Perform the Diagnostic Repair Verification (See: Verification Tests) after completing the repair.
* Vehicle Speed Sensor Replacement (See: Powertrain Management/Computers and Control Systems/Sensors and Switches - Computers and
Control Systems/Vehicle Speed Sensor/Service and Repair/Tremec 6-Speed - Manual Transmission)
* Control Module References (See: Testing and Inspection/Programming and Relearning) for ECM replacement, setup and programming
P0503
DTC P0502 or P0503
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Diagnostic System
Check - Vehicle) prior to using this diagnostic procedure.
* Review Strategy Based Diagnosis (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/Strategy Based Diagnosis) for an
overview of the diagnostic approach.
* Diagnostic Procedure Instructions (See: Testing and Inspection/Initial Inspection and Diagnostic Overview/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
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掳C (-40掳F)
* The engine speed is 1,500-6,500 RPM.
* Vehicle speed is less than 200 km/h (124 mph).
* Engine torque is 68-8192 Nm (50-6,042 lb ft).
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.
Conditions for Setting the DTC
P0502
The transmission output speed is 58 RPM or less for 5 seconds.
