GM Service Manual Online
For 1990-2009 cars only
Table 1: DTC C1232 LF Wheel Speed Sensor Circuit Open or Shorted

Object Number: 393826  Size: MF
ABS Components
Antilock Brake System Schematics
Handling Electrostatic Discharge Sensitive Parts Notice

Circuit Description

The speed sensor used on this vehicle is a multiple pole magnetic pickup. This sensor produces an AC signal that the EBCM/EBTCM uses the frequency from to calculate the wheel speed.

Conditions for Setting the DTC

The DTC can be set any time the ignition is in the ON position, and the EBCM/EBTCM senses any one of the following:

    • A open circuit is seen for 0.02 seconds.
    • A short to battery voltage is seen for 0.02 seconds.
    • A short to ground is seen for 0.02 seconds.

Action Taken When the DTC Sets

    • A malfunction DTC stores.
    • The ABS/TCS disables.
    • The ABS/TCS indicator(s) turn 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.
    • 100 ignition cycles pass with no DTC(s) detected.

Diagnostic Aids

    • It is very important that a thorough inspection of the wiring and connectors be performed. Failure to carefully and fully inspect wiring and connectors may result in misdiagnosis, causing part replacement with reappearance of the malfunction.
    • Thoroughly inspect any circuitry that may be causing the complaint for the following conditions:
       - Backed out terminals
       - Improper mating
       - Improperly formed or damaged terminals
       - Poor terminal-to-wiring connections
       - Physical damage to the wiring harness
    • The following conditions may cause an intermittent malfunction:
       - A poor connection
       - Rubbed-through wire insulation
       - A broken wire inside the insulation
    • If the customer's comments reflect that the ABS/TCS indicator is on only during moist environmental conditions (rain, snow, vehicle wash), inspect all the wheel speed sensor circuitry for signs of water intrusion. If the DTC is not current, clear all DTCs and simulate the effects of water intrusion by using the following procedure:
        1. Spray the suspected area with a five percent saltwater solution.

Add two teaspoons of salt to twelve ounces of water to make a five percent saltwater solution.

        2. Test drive the vehicle over various road surfaces (bumps, turns, etc.) above 40 km/h (25 mph) for at least 30 seconds.
        3. If the DTC returns, replace the suspected WSS or WSS harness.
    • If an intermittent malfunction exists refer to Intermittents and Poor Connections Diagnosis in Wiring Systems for further diagnosis.

Front Wheel Speed Sensor Resistance

The following table contains resistance values for the front wheel speed sensors at varying sensor temperatures for use in diagnosis. The values are approximate and should be used as a guideline for diagnosis.

Sensor Temperature (°C)

Sensor Temperature (°F)

Sensor Resistance (Ohms)

-34 to 4

-30 to 40

800 to 1100

5 to 43

41 to 110

950 to 1300

44 to 93

111 to 200

1100 to 1600

Test Description

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

  1. Checks for an open in the WSS or WSS CKT.

  2. Checks for a short to ground in the WSS CKT.

  3. Checks for a short to voltage in the WSS CKT.

  4. Checks for a short to voltage in the WSS CKT.

DTC C1232 LF Wheel Speed Sensor Circuit Open or Shorted

Step

Action

Value(s)

Yes

No

1

Was the Diagnostic System Check performed?

--

Go to Step 2

Go to Diagnostic System Check - ABS

2

  1. Inspect the WSS wiring and connectors for damage.
  2. Inspect the WSS and for looseness or damage.

Is physical damage of sensor evident?

--

Go to Step 3

Go to Step 4

3

Replace the WSS. Refer to Wheel Speed Sensor Replacement .

Is the replacement complete?

--

Go to Step 17

--

4

Inspect the jumper harness for physical damage.

Is physical damage of the jumper harness evident?

--

Go to Step 5

Go to Step 6

5

Replace the jumper harness. Refer to Wheel Speed Sensor Jumper Harness Replacement .

Is the replacement complete?

--

Go to Step 17

--

6

  1. Turn the ignition switch to the OFF position.
  2. Disconnect the EBCM/EBTCM.
  3. Install the J 39700 Universal Pinout Box using the J 39700-99 Cable Adapter to the EBCM/EBTCM harness connector only.
  4. Using J 39200 DMM, measure the resistance between terminals A9 and A10 of J 39700 Universal Pinout Box.

Is the resistance within the range specified in the value(s) column?

800-1600 ohms

Go to Step 8

Go to Step 7

7

  1. Disconnect the LF wheel speed sensor.
  2. Using J 39200 DMM, measure the resistance between terminals A and B of the Wheel Speed Sensor Connector.

Is the resistance within the range specified in the value(s) column?

800-1600 ohms

Go to Step 9

Go to Step 3

8

  1. Connect the J 39200 DMM between terminals A9 and D of J 39700 the Universal Pinout Box.
  2. Then connect the J 39200 DMM between terminals A10 and D of J 39700 the Universal Pinout Box.
  3. Measure for continuity to ground in both CKT 830 and CKT 873.

Is continuity to ground present in either CKT 830 or CKT 873?

--

Go to Step 19

Go to Step 9

9

  1. Connect a jumper wire between the LF wheel speed sensor harnesss connector B and a known good ground.
  2. Using J 39200 DMM, measure the resistance between terminals A9 and D of J 39700 Universal Pinout Box.

Is the resistance within the range specified in the value(s) column?

0-2 ohms

Go to Step 11

Go to Step 10

10

  1. Repair CKT 873 for an open or high resistance. Refer to Wiring Repairs in wiring systems.
  2. If open or high resistance is found in jumper harness, replace the jumper harness. Refer to Wheel Speed Sensor Jumper Harness Replacement .

Is the repair complete?

--

Go to Step 11

--

11

  1. Connect a jumper wire between the RF wheel speed sensor harnesss connector A and a known good ground.
  2. Using J 39200 DMM, measure the resistance between terminals A10 and D of J 39700 Universal Pinout Box.

Is the resistance within the range specified in the value(s) column?

0-2 ohms

Go to Step 13

Go to Step 12

12

  1. Repair CKT 830 for an open or high resistance. Refer to Wiring Repairs in wiring systems.
  2. If open or high resistance is found in jumper harness, replace the jumper harness. Refer to Wheel Speed Sensor Jumper Harness Replacement .

Is the repair complete?

--

Go to Step 13

--

13

  1. Turn the ignition switch to the RUN position, engine off.
  2. Using J 39200 DMM, measure the voltage between terminals A9 and D of J 39700 Universal Pinout Box.

Is the voltage within the range specified in the value(s) column?

Below 1 V

Go to Step 15

Go to Step 14

14

  1. Repair CKT 873 for a short to voltage.
  2. If short to voltage is found in jumper harness, replace the jumper harness. Refer to Wheel Speed Sensor Jumper Harness Replacement .

Is the repair complete?

--

Go to Step 15

--

15

Using J 39200 DMM, measure the voltage between terminals A10 and D of J 39700 Universal Pinout Box.

Is the voltage within the range specified in the value(s) column?

Below 1 V

Go to Step 17

Go to Step 16

16

  1. Repair CKT 830 for a short to voltage.
  2. If short to voltage is found in jumper harness, replace the jumper harness. Refer to Wheel Speed Sensor Jumper Harness Replacement .

Is the repair complete?

--

Go to Step 17

--

17

  1. Reconnect all previously disconnected components.
  2. Using a scan tool clear the DTC.
  3. Carefully drive the vehicle above 24 Km/h (15 mph) for several minutes.

Does the DTC reset as a current DTC?

--

Go to Step 18

System OK

18

Replace the EBCM/EBTCM. Refer to Electronic Brake Control Module/Electronic Brake and Track Control Module Replacement .

Is the replacement complete?

--

Go to Diagnostic System Check - ABS

--

19

  1. Repair CKT 830 or CKT 873 for a short to ground.
  2. If short to ground is found in jumper harness, replace the jumper harness. Refer to Wheel Speed Sensor Jumper Harness Replacement .

Is the repair complete?

--

Go to Step 17

--