GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The toothed wheel generates a voltage pulse as it moves past the wheel speed sensor (WSS). Each tooth-gap-tooth series on the wheel generates the pulses. The electronic brake control module (EBCM) uses the frequency of these pulses to determine wheel speed. The voltage generated depends on the air gap between the WSS and the toothed wheel, and on the wheel speed.

This DTC will set when the EBCM cannot identify which WSS is causing the malfunction. It is necessary to inspect all WSS and associated wiring to determine the cause of the DTC.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC C0245 Wheel Speed Sensor Malfunction

Conditions for Running the DTC

    • Vehicle speed is greater than 6 km/h (4 mph) with the brake pedal not applied
        or
    • Vehicle speed is greater than 15 km/h (9 mph) and the brake pedal is actuated.

Conditions for Setting the DTC

    • Incorrect number of teeth on the toothed wheel
    • Damaged or broken teeth on the toothed wheel
    • Discontinuity or short in the WSS wiring

Action Taken When the DTC Sets

The following actions occur:

    • The antilock brake system (ABS) is disabled.
    • The ABS warning indicator turns is ON.

Conditions for Clearing the DTC

The condition responsible for setting the DTC no longer exists and the scan tool Clear DTCs function is used.

Diagnostic Aids

DTC C0245 may be set by running the scan tool auto test if the throttle angle readings are not updating while in the data list mode. If this is the case, clear the DTCs, disconnect the scan tool, and road test the vehicle to at least 12 km/h (7 mph) to see if the DTC resets.

Inspect the toothed wheels for any large grooves, gouges, marks, etc. that might influence the tooth's signal at the WSS. Also inspect for a buildup of foreign material in the gaps between the teeth in the toothed wheel. A buildup of foreign material may cause this malfunction.

A badly worn hub/bearing assembly may cause this malfunction. The WSS-to-toothed wheel air gap may change excessively due to bearing play. If an improper rear hub assembly or front outer constant velocity joint is installed, one with a toothed wheel containing the incorrect number of teeth, this DTC can set. Be sure that the front and the rear toothed wheel have 40 teeth.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

  1. This step begins the examination of the front WSS.

  2. This step inspects for a problem with one of the front toothed rings.

  3. This step inspects the front WSS.

  4. This step inspects for shorts in a front WSS harness.

  5. This step inspects for opens in a front WSS harness.

  6. This step begins an inspection of the rear WSS.

  7. This step inspects for a problem with one of the rear toothed rings.

  8. This step inspects the rear WSS.

  9. This step inspects for shorts in a rear WSS harness.

  10. This step inspects for opens in a rear WSS harness.

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

Go to Diagnostic System Check - Vehicle

2

Visually inspect the wiring for the front wheel speed sensors (WSS).

Is there any damage?

--

Go to Step 3

Go to Step 4

3

Verify that the correct outer constant velocity (CV) joints are installed on the vehicle. The front speed rings have 47 teeth and the rear speed rings have 40 teeth.

Did you complete the action?

--

Go to Step 23

--

4

Inspect fuse EF2 in the engine fuse block.

Is fuse EF2 open?

--

Go to Step 5

Go to Step 6

5

Replace fuse EF2.

Did you complete the replacement?

--

Go to Step 23

--

6

  1. Disconnect the WSS harnesses from the WSS connectors.
  2. Measure the WSS resistance at the WSS connector terminals.

Does the resistance measure within the specified range for both WSS?

1000-1500 ohms

Go to Step 8

Go to Step 7

7

Replace the faulty WSS. Refer to Front Wheel Speed Sensor Replacement or Rear Wheel Speed Sensor Replacement .

Did you complete the replacement?

--

Go to Step 23

--

8

  1. Disconnect the electronic brake control module (EBCM) connector.
  2. Test each WSS harness for a short circuit between its wires at the harness side of the WSS connector.
  3. Test each WSS circuit for a short to ground from the harness connector terminals.

Is there any short circuit in either WSS harness?

--

Go to Step 9

Go to Step 10

9

Repair the short circuit in the wiring.

Did you complete the repair?

--

Go to Step 23

--

10

Test the continuity of the wiring in both front WSS circuits between the EBCM connector and the WSS connector on each side of the vehicle.

    • The left side uses terminals 6 and 7 at the EBCM connector.
    • The right side uses terminals 4 and 5 at the EBCM connector.

Is the continuity good for both harnesses?

--

Go to Step 12

Go to Step 11

11

Repair the open or high resistance in the front WSS harness.

Did you complete the repair?

--

Go to Step 23

--

12

  1. Visually inspect the wiring for the rear WSS.
  2. Make sure that the WSS are properly mounted and that the retaining bolts are properly tightened.

Is there any damage?

--

Go to Step 13

Go to Step 14

13

Repair or replace components as required.

Did you find and correct the condition?

--

Go to Step 23

--

14

Remove each WSS from the rear knuckles and inspect the toothed ring through the WSS mounting holes.

    • Inspect for any damaged or missing teeth.
    •  Inspect that the ring is properly positioned under the WSS.

Is there any damage or other fault with either speed ring?

--

Go to Step 15

Go to Step 16

15

Replace the rear wheel hub with the proper unit.

Did you complete the replacement?

--

Go to Step 23

--

16

  1. Disconnect the rear WSS harnesses from the WSS connectors.
  2. Measure the WSS resistance at the WSS connector terminals.

Does the resistance measure within the specified range for both WSS?

1000-1500 ohms

Go to Step 18

Go to Step 17

17

Replace the faulty WSS. Refer to Front Wheel Speed Sensor Replacement or Rear Wheel Speed Sensor Replacement .

Did you complete the replacement?

--

Go to Step 23

--

18

  1. Disconnect the EBCM connector.
  2. Test each WSS harness for a short circuit between its wires at the harness side of the WSS connector.
  3. Test each WSS harness wire for a short to ground from the connector terminals.

Is there any short circuit in either WSS harness?

--

Go to Step 19

Go to Step 20

19

Repair the short circuit in the wiring.

Did you complete the repair?

--

Go to Step 23

--

20

Test the continuity of the wiring in both rear WSS circuits between the ABS connector and the WSS connector on each side of the vehicle.

    • The left side uses terminals 8 and 9 at the ABS connector.
    • The right side uses terminals 1 and 3 at the ABS connector.

Is continuity good for both harnesses?

--

Go to Step 22

Go to Step 21

21

Repair the open or high resistance in the rear WSS harness or connector C205.

Did you complete the repair?

--

Go to Step 23

--

22

Replace the EBCM. Refer to Brake Pressure Modulator Valve Assembly Replacement .

Did you complete the replacement?

--

Go to Step 23

--

23

  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 2

System OK