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.
DTC Descriptors
This diagnostic procedure supports the following DTCs:
| • | DTC C0055 Rear Wheel Speed Sensor (Both Wheels) Circuit |
| • | DTC P0609 Rear Wheel Speed Sensor (Both Wheels) Circuit |
Conditions for Running the DTC
C0055
Conditions for running as usual
| • | The ignition is ON. |
| • | The vehicle speed is greater than 13 km/h (8 mph). |
P0609
Conditions for running as usual
| • | 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/dynamic rear proportion (DRP). |
| • | The ABS indicator turns ON. |
| • | The brake warning indicator turns ON. |
| • | An ECE 13 response may occur. Refer to ABS Description and Operation for a complete description of ECE 13. |
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. Refer to Testing for Intermittent Conditions and Poor Connections , Connector Repairs , Testing for Electrical Intermittents , and Wiring Repairs .
Test Description
The numbers below refer to the step numbers on the diagnostic table.
-
This step tests for a voltage signal from the PCM.
-
This step tests for a missing or erratic vehicle speed signal from the PCM. An assistant may be required to perform this test.
Step | Action | Values | Yes | No |
|---|---|---|---|---|
Schematic Reference: Antilock Brake System Schematics Connector End View Reference: Antilock Brake System Connector End Views | ||||
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | |
2 |
Does the DTC set? | 13 km/h (8 mph) | Go to Step 3 | Go to Diagnostic Aids |
Does the voltage measure greater than the specified value? | 10 V | Go to Step 4 | Go to Step 7 | |
Does the voltage measure within the specified range for the entire time that the driveshaft is rotating? | 5-7 V | Go to Step 5 | Go to Step 7 | |
5 | Inspect for poor connections at the harness connector of the EBCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 10 | Go to Step 6 |
6 |
Important: Following EBCM replacement, use the scan tool to perform the Tire Size Calibration procedure. Replace the EBCM. Refer to Control Module References . Did you complete the replacement? | -- | Go to Step 10 | -- |
7 | Test the vehicle speed signal circuit for an open, a short to ground, or a short to voltage. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | -- | Go to Step 10 | Go to Step 8 |
8 | Inspect for poor connections at the harness connector of the powertrain control module (PCM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | -- | Go to Step 10 | Go to Step 9 |
9 |
Important: Perform the setup procedure for the PCM. Replace the PCM. Refer to Control Module References . Did you complete the replacement? | -- | Go to Step 10 | -- |
10 |
Does the DTC reset? | -- | Go to Step 3 | System OK |
