GM Service Manual Online
For 1990-2009 cars only

Object Number: 393827  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 will set if the right front wheel speed = 0 and the other wheel speeds are greater than 8 Km/h (5 mph) for 2.5 seconds.

This DTC can only be set with the following conditions:

    • When DTC C1232 through C1235 are not set as a current DTC(s).
    • Vehicle is not in an ABS stop.
    • Brake switch is off.

Action Taken When the DTC Sets

    • A malfunction DTC stores.
    • The ABS/ETS/TCS disables.
    • The amber ABS/ETS/TCS indicator(s) turn on.

Conditions for Clearing the DTC

    • Condition for DTC is no longer present and scan tool clear DTC function is used.
    • 100 ignition cycles have passed 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.
    • An intermittent malfunction can be caused by poor connections, broken insulation, or a wire that is broken inside the insulation.
    • If an intermittent malfunction exists refer to Intermittents and Poor Connections Diagnosis in Wiring Systems.

Test Description

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

  1. Checks the resistance of the WSS.

  2. Checks if the WSS CKTs are shorted together.

DTC C1222 RF Wheel Speed Sensor Input is 0

Step

Action

Value(s)

Yes

No

1

Was the Diagnostic System Check performed?

--

Go to Step 2

Go to Diagnostic System Check - ABS

2

Did DTC C1233 set as a current or history DTC?

--

Go to DTC C1233 RF Wheel Speed Circuit Open or Shorted

Go to Step 3

3

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

Is physical damage of sensor evident?

--

Go to Step 4

Go to Step 5

4

Replace wheel speed sensor. Refer to Wheel Speed Sensor Replacement .

Is the repair complete?

--

Go to Step 11

--

5

Inspect the WSS jumper harness for physical damage.

Is physical damage to the jumper harness evident?

--

Go to Step 6

Go to Step 7

6

Replace wheel speed sensor jumper harness. Refer to Wheel Speed Sensor Jumper Harness Replacement .

Is the repair complete?

--

Go to Step 11

--

7

  1. Disconnect the WSS at the sensor pigtail.
  2. Using J 39200 DMM, measure the resistance between terminals A and B of the WSS.

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

850-1350 ohms

Go to Step 8

Go to Step 4

8

  1. With J 39200 DMM still connected, select the mV AC scale.
  2. Spin the wheel at approximately 1 revolution per second by hand while monitoring the AC output.
  3. While monitoring the AC output notice if the reading on the J 39200 DMM goes below 100 mV.

Does AC voltage fall below the range specified in the value(s) column?

100 mV

Go to Step 4

Go to Step 9

9

  1. Disconnect the EBCM/EBTCM harness connector.
  2. Install the J 39700 Universal Pinout Box using the J 39700-99 Cable Adapter to the EBCM/EBTCM harness connector only.
  3. Using J 39200 DMM, measure for continuity between terminals A7 and A8 of the J 39700 Universal Pinout Box.

s continuity present between terminals A7 and A8 of the J 39700 Universal Pinout Box?

--

Go to Step 10

Go to Step 11

10

Repair the short between CKT(s) 872 and 833. If short is found in jumper harness, replace the jumper harness assembly.

Is the repair complete?

--

Go to Step 11

--

11

  1. Reconnect all connectors.
  2. Using a scan tool, clear the DTC.
  3. Carefully test drive vehicle above 24 Km/h (15 mph) for at least 30 seconds while monitoring a scan tool.

Does DTC reset as a current DTC?

--

Go to Step 12

System OK

12

Replace 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

--