GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Cadillac 🢒 2006 🢒 Escalade ESV 🢒 Accessories 🢒 Navigation Systems 🢒 DTC C0235-C0237 or P0609

Circuit Description

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

DTC Descriptors

This diagnostic procedure supports the following DTCs:

    • DTC C0235 Rear Wheel Speed Signal Circuit Open
    • DTC C0236 Rear Wheel Speed Signal Missing
    • DTC C0237 Rear Wheel Speed Signal Erratic

Conditions for Running the DTC

C0235

The ignition is ON.

C0236 and C0237

    • The ignition is ON.
    • The vehicle speed is greater than 32 km/h (20 mph) when the brake is applied or 19 km/h (12 mph) when the brake is released.

P0609

    • The ignition is ON.
    • The vehicle is not moving.

Conditions for Setting the DTC

C0235

The EBCM detects low voltage on the vehicle speed signal circuit for 500 milliseconds.

C0236

The rear wheel speed signal is less than 6 km/h (4 mph) for 5 seconds, or 120 seconds in order to set multiple missing sensor signal DTCs.

C0237

The EBCM detects an erratic rear wheel speed signal for 105 milliseconds.

P0609

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

Action Taken When the DTC Sets

If equipped, the following actions occur:

    • The EBCM disables the ABS/TCS/DRP.
    • The ABS indicator turns ON.
    • The TRACTION OFF indicator turns ON.
    • The red brake warning indicator turns ON.

Conditions for Clearing the DTC
    • Repair the condition responsible for setting the DTC.
    • Use a scan tool in order to clear the DTC.
    • After the DTC is cleared and the ignition is ON, the ABS indicator may remain ON until the EBCM completes a power-up self-test. This test concludes when the vehicle reaches a speed greater than 13 km/h (8 mph) and the wheel speeds are verified by the EBCM.

Diagnostic Aids

Thoroughly inspect connections or circuitry that may cause an intermittent malfunction. Refer to the following:

    •  Testing for Electrical Intermittents
    •  Testing for Intermittent Conditions and Poor Connections
    •  Wiring Repairs
    •  Connector 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.

  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

Connector End View Reference: Antilock Brake System Connector End Views , Powertrain Control Module Connector End Views for the 4.8L, 5.3L engine and 6.0L engine or Powertrain Control Module Connector End Views for the 8.1L engine

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?

19 km/h (12 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. Set up the DMM in order to measure the DC voltage between the vehicle speed signal circuit and a good ground.
  4. Spin the rear wheels as fast as possible 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 the entire time 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 in Wiring Systems

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