P0609

DTC C0055 or P0609

Circuit Description
The powertrain control module (PCM) converts the signal from the vehicle speed sensor (VSS) to a 128k pulses/mile signal. The electronic brake control module (EBCM) uses the vehicle speed signal from the PCM to calculate the rear wheel speed.

Conditions for Running the DTC

C0055
^ The ignition is ON.
^ The vehicle speed is greater than 13 km/h (8 mph).

P0609
^ The ignition is ON.
^ The vehicle is not moving.

Conditions for Setting the DTC

C0055
Any of the following occurrences may cause the DTC to set.
^ The EBCM detects an open or shorted vehicle speed signal circuit for 500 milliseconds.
^ The EBCM detects the absence of the vehicle speed signal for 5 seconds. If more than one absent wheel speed sensor signal is detected, the condition must be present for 120 seconds to set DTCs.
^ The EBCM detects an erratic vehicle speed signal for 200 milliseconds.

P0609
The PCM detects low voltage on the vehicle speed signal circuit for 45 seconds.

Action Taken When the DTC Sets
^ The EBCM disables the ABS/DRP.
^ The ABS indicator turns ON.
^ The brake warning indicator turns ON.
^ An ECE 13 response may occur.

Conditions for Clearing the DTC
The Conditions for Setting the DTC are no longer present and you use the scan tool Clear DTCs function.

Diagnostic Aids
Thoroughly inspect connections or circuitry that may cause an intermittent malfunction.

Test Description

Steps 1-8:

Steps 8-10:

The numbers below refer to the step numbers on the diagnostic table.
3. This step tests for a voltage signal from the PCM.
4. This step tests for a missing or erratic vehicle speed signal from the PCM. An assistant may be required to perform this test.