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 Traction Off Indicator Inoperative

Circuit Description

The ignition 3 voltage circuit supplies a momentary application of ground to the traction control switch. The electronic brake control module (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

For all traction control DTC resets, verify EC30 ECU configuration by turning the ignition ON and monitoring the ECU LEDs.

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 stuck open contacts in the traction switch.

    3.

  3. This step tests for stuck closed contacts in the traction switch.

    4.

  4. This step tests for an open or short to ground in the service traction control signal circuit.

    5.

  5. This step tests for an open or short to ground in the traction control switch 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 Traction Off indicator.

Does the Traction Off indicator illuminate for 3 seconds and then turn OFF?

Go to Step 4

Go to Step 3

3
  1. Turn OFF the ignition.
  2. Disconnect the traction control switch harness connector.
  3. Connect a test lamp between the service traction control signal circuit and B+.
  4. Turn ON the ignition.
  5. Press and hold the traction control switch.

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

Go to Step 7

Go to Step 9

4

Press and release the traction control switch.

Does the Traction Off indicator turn ON ?

Go to Diagnostic Aids

Go to Step 5

5

Important: Do not disconnect the traction control switch harness connector during this step.

  1. Access the traction control switch harness connector. Refer to Air ABS Traction Control Switch Replacement .
  2. Backprobe the traction control switch signal circuit with a test lamp connected to B+.
  3. Refer to Probing Electrical Connectors .
  4. While observing the Traction Off indicator, momentarily contact and release the traction control switch signal circuit with the test lamp several times.

Does the Traction Off indicator turn ON and OFF?

Go to Step 7

Go to Step 6

6

  1. Disconnect the traction switch connector harness.
  2. Connect a test lamp to B+ and probe the service traction control signal circuit. Refer to Probing Electrical Connectors .
  3. While observing the test lamp, momentarily contact and release the traction control switch signal circuit with a fused jumper wire connected to a good ground. Refer to Using Fused Jumper Wires .

Does the test lamp turn ON ?

Go to Step 7

Go to Step 9

7

Inspect for poor connections at the traction control switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs .

Did you find and correct the condition?

Go to Step 11

Go to Step 8

8

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

Did you complete the replacement?

Go to Step 12

--

9

  1. Turn OFF the ignition.
  2. Disconnect from the electronic brake control module (EBCM), the harness connector containing the service traction control signal circuit.
  3. Test the service traction control signal circuit for an open or short to ground. Refer to Circuit Testing and Wiring Repairs .

Did you find the correct condition?

Go to Step 12

Go to Step 10

10

With the EBCM harness still disconnected, test the traction control switch signal circuit for an open or short to ground. Refer to Circuit Testing and Wiring Repairs .

Did you find the correct condition?

Go to Step 12

Go to Step 11

11

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

Did you complete the replacement?

Go to Step 12

--

12
  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