For 1990-2009 cars

### 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 Descriptor

This diagnostic procedure supports the following DTC:

DTC C0055 Rear Wheel Speed Sensor Circuit

### Conditions for Running the DTC

• | The ignition is ON.

• | The vehicle speed is greater than 30 km/h (19 mph).

### Conditions for Setting the DTC

• | The EBCM detects an open or shorted vehicle speed signal circuit for 200 milliseconds.

• | The EBCM detects the absence of the vehicle speed signal for one second. If more than one absent wheel speed sensor signal is detected, the condition must be present for 20 seconds to set DTCs.

• | The EBCM detects an erratic vehicle speed signal for 40 continuous or cumulative milliseconds.

### Action Taken When the DTC Sets

If equipped, the following actions occur:

• | The EBCM disables the Antilock Brake System (ABS).

• | The ABS indicator turns ON.

• | The EBCM disables the traction control switch (TCS).

• | The traction fault message is displayed.

• | The EBCM disables the dynamic rear proportion (DRP), if all wheel speed inputs have failed.

• | The brake warning indicator turns ON, if DRP is disabled.

• | The brakes message is displayed, if DRP is disabled.

• | An ECE 13 response occurs. 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.

1. This step tests for a voltage signal from the PCM.

2. 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
1 | Did you perform the Diagnostic System Check - Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 |

1. Use a scan tool in order to clear the DTCs.
2. Operate the vehicle at a speed greater than the specified value.

Does the DTC set?

30 km/h (19 mph)

Go to Step 3

Go to Diagnostic Aids

3 |

1. Turn OFF the ignition.
2. Disconnect from the electronic brake control module (EBCM), the harness connector containing the vehicle speed signal circuit.
3. Turn ON the ignition.
4. Use a DMM in order to measure the DC voltage between the vehicle speed signal circuit and a good ground.

Does the voltage measure greater than the specified value?

10 V

Go to Step 4

Go to Step 7

4 |

1. Raise and support the vehicle. Refer to Lifting and Jacking the Vehicle .
2. Place the transmission in neutral (N).
3. Setup the DMM in order to measure the DC voltage between the vehicle speed signal circuit and a good ground.
4. Slowly spin the rear wheels by hand for at least 30 seconds and while ensuring the driveshaft is rotating, observe the DMM.

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 | Replace the EBCM. Refer to Control Module References for replacement, setup, and programming. 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 | Replace the PCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | -- | Go to Step 10 | --
10 |

1. Use the scan tool in order to clear the DTCs.
2. Operate the vehicle within the Conditions for Running the DTC, as specified in the supporting text.

Does the DTC reset?

--

Go to Step 3

System OK