GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2004 🢒 TopKick C-Series (Conventional) C4/C5 🢒 Brakes 🢒 Air Antilock Brake System 🢒 Air Traction Off Indicator Always On

Circuit Description

The ignition 3 voltage circuit supplies 12 volts to the traction control switch. The EBCM illuminates the traction off indicator by applying voltage to the service traction control signal circuit.

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 proper operation of the traction off indicator.

    2.

  2. This step tests for proper operation of the traction switch.

    3.

  3. This step tests for proper operation of the EBCM and harness containing the service traction control active signal circuit.

Step

Action

Yes

No

Schematic Reference: Air Antilock Brake System Schematics

Connector End View Reference: Air Brake System Component Views

1

Did you perform the ABS Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Air ABS

2

  1. Turn OFF the ignition for 5 seconds.
  2. Turn ON the ignition while observing the traction off indicator.

Does the traction off indicator illuminate for 3 seconds and then turn OFF?

Go to Diagnostic Aids

Go to Step 3

3

  1. Turn OFF the ignition.
  2. Disconnect the traction control switch harness connector.
  3. Connect test lamp between the service traction control signal circuit and a good ground. Refer to Probing Electrical Connectors in Wiring Systems.
  4. Turn the ignition ON.

Does the test lamp illuminate for 3 seconds and then turn off?

Go to Step 4

Go to Step 5

4

Replace the traction control switch. Refer to Air ABS Traction Control Switch Replacement .

Did you complete the replacement?

Go to Step 8

--

5

  1. Turn OFF the ignition.
  2. Disconnect from the EBCM, the harness connector containing the service traction control signal circuit.
  3. With the test lamp still connected, turn ON the ignition.

Does the test lamp illuminate?

Go to Step 6

Go to Step 7

6

Repair short to voltage in the service traction control circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

Go to Step 8

--

7

Important: Following EBCM replacement, perform the EBCM self-configuration procedure.

Replace the EBCM. Refer to Electronic Brake Control Module Replacement .

Did you complete the replacement?

Go to Step 8

--

8
  1. Turn OFF the ignition for 5 seconds.
  2. Turn ON the ignition while observing the low traction indicator.

Does the low traction indicator illuminate for 3 seconds and then turn OFF?

System OK

Go to Step 3