GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 HUMMER 🢒 2003 🢒 H2 🢒 Brakes 🢒 Antilock Brake System 🢒 DTC B3626

Circuit Description

The TC2 mode switch is a momentary-contact switch that can be used to limit the traction control function. Each time the TC2 mode switch is pressed, the TC2 switch full traction limited status changes. When the TC2 mode switch is released, voltage on the TC2 mode switch signal circuit is approximately 12  volts. When the TC2 mode switch is pressed, voltage on the TC2 mode switch signal circuit is approximately 0.5 volts.

Conditions for Running the DTC

In order to detect a continuously low or high TC2 mode switch signal:

The ignition is ON.

OR:

In order to detect a continuously pressed TC2 mode switch:

    • The ignition is ON.
    • The engine speed is greater than 450 RPM.

Conditions for Setting the DTC

Either of the following conditions may cause DTC B3626 to set:

    • The TC2 mode switch signal is detected as excessively low or high for 200 milliseconds.
    • The TC2 mode switch is detected as pressed for 60 seconds.

Action Taken When the DTC Sets
    • The EBCM disables the traction assist.
    • The TCS LED switch telltale is disable.

Conditions for Clearing the DTC

The conditions for setting the DTC are no longer present and you use the scan tool Clear DTCs function.

Diagnostic Aids

Press and release the TC2 mode switch several times while observing the traction LED switch telltale in order to verify that the TC2 full traction limited status changes each time the switch is pressed and that DTC B3626 does not set. Using the scan tool in order to observe the Mode Switch Pressed or Released status may also be helpful in diagnosing an intermittent fault within the switch.

Thoroughly inspect connections or circuitry that may cause an intermittent malfunction. Refer to Testing for Electrical Intermittents , Testing for Intermittent Conditions and Poor Connections , Wiring Repairs and Connector Repairs in Wiring Systems.

Test Description

The number below refers to the step number on the diagnostic table.

  1. This step tests for voltage on the TC2 mode switch signal circuit indicating an unpressed TC2 mode switch.

    2.

  2. This step tests for voltage on the TC2 mode switch signal circuit indicating a pressed TC2 mode switch.

Step

Action

Values

Yes

No

Schematic Reference: Antilock Brake System Schematics

Connector End View Reference: Antilock Brake System Connector End Views

1

Did you perform the ABS Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check - ABS

2
  1. Use a scan tool in order to clear the DTCs.
  2. Turn OFF the ignition for 5 seconds.
  3. Start the engine.
  4. Observe the scan tool for up to 60 seconds in order to verify the DTC resets.

Does the DTC set?

--

Go to Step 3

Go to Diagnostic Aids

3
  1. Turn OFF the ignition.
  2. Disconnect the TC2 mode switch harness connector.
  3. Turn ON the ignition.
  4. Connect a test lamp between the IGN 1 voltage circui, IGN E fuse, and a good ground.

Does the test lamp illuminate?

--

Go to Step 4

Go to Step 11

4

  1. Turn OFF the ignition.
  2. Reconnect the TC2 mode switch harness connector.
  3. Turn ON the ignition.
  4. Backprobe the TC2 mode switch harness connector in order to connect a DMM between the TC2 mode switch signal circuit and a good ground. Refer to Probing Electrical Connectors in Wiring Systems.
  5. Measure the DC voltage on the TC2 mode switch signal circuit.

Does the TC2 mode switch signal measure with in the specified range?

12 V

Go to Step 5

Go to Step 6

5

  1. Press and hold the TC2 mode switch.
  2. Use a DMM in order to measure the DC voltage on the TC2 mode switch signal circuit.

Does the TC2 mode switch signal measure within the specified range?

0.5 V

Go to Step 7

Go to Step 13

6

Test the TC2 mode switch signal circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 14

Go to Step 12

7
  1. Turn OFF the ignition.
  2. Disconnect the wiring harness connector from the EBCM.
  3. Connect the J 39700 universal pinout box using the J 39700-530 cable adapter to the EBCM harness connector only.
  4. Turn ON the ignition.
  5. Use a DMM in order to measure the DC voltage on the TC2 mode switch signal circuit.

Does the TC2 mode switch signal measure within the specified range?

12 V

Go to Step 9

Go to Step 8

8

Repair the open in the TC2 mode switch signal circuit. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 14

--

9

Inspect for poor connections at the harness connector of the EBCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 14

Go to Step 10

10

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

Did you complete the replacement?

--

Go to Step 14

--

11

Repair the open or short to ground in the IGN 1 voltage circuit, IGN E fuse. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Step 14

--

12

Inspect for open in the TC2 switch ground circuit or poor connections at the harness connector of the TC2 mode switch. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 14

Go to Step 13

13

Replace the TC2 mode switch. Refer to Electronic Traction Control Switch Replacement

Did you complete the replacement?

--

Go to Step 14

--

14
  1. Use the scan tool in order to clear the DTCs.
  2. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text.

Does the DTC reset?

--

Go to Step 3

System OK