GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 GMC_Truck 🢒 2005 🢒 TopKick C-Series (Crew) C4/C5 🢒 Brakes 🢒 Air Antilock Brake System 🢒 Air Low Traction Indicator Always On

Circuit Description

The ignition 3 voltage circuit supplies 12 volts to the traction control switch. The electronic brake control module (EBCM) illuminates the Low Traction indicator by applying ground to the traction control active 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
    •  Connector Repairs
    •  Wiring Repairs

Test Description

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

  1. This step tests for proper operation of the Low Traction 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 the 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 Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

  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?

Go to Diagnostic Aids

Go to Step 3

3

  1. Turn OFF the ignition.
  2. Disconnect traction control switch harness connector.
  3. Connect a test lamp between battery positive voltage and the traction control active signal circuit.
  4. Turn ON the ignition.

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

Go to Step 6

Go to Step 4

4

  1. Turn OFF the ignition.
  2. Disconnect from the electronic brake control module (EBCM), the harness connector containing the traction control active signal circuit.
  3. With the test lamp still connected, turn ON the ignition.

Does the test light illuminate?

Go to Step 5

Go to Step 7

5

Repair the short to ground in traction control active signal circuit. Refer to Wiring Repairs .

Did you complete the repair?

Go to Step 8

--

6

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

Did you complete the replacement?

Go to Step 8

--

7

Replace the EBCM. Refer to Control Module References for replacement, setup, and programming.

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