GM Service Manual Online
For 1990-2009 cars only

Object Number: 413328  Size: LF
ABS Components
Cell 44: Class 2, Stoplamp/BTSI Switch, and Traction Control Switch
Handling ESD Sensitive Parts Notice
Cell 10: LAMPS Fuse
(Cell 34: Power and Ground and VSS Inputs)
Cell 110: Turn Signal Flasher, Hazard Flasher, and Stoplamp/BTSI Switch
Cell 110: Turn Signal Flasher, Hazard Flasher, and Stoplamp/BTSI Switch
Cell 110: Turn Signal Flasher, Hazard Flasher, and Stoplamp/BTSI Switch
Cell 110: Turn Signal Flasher, Hazard Flasher, and Stoplamp/BTSI Switch

Circuit Description

This circuit detects an open stoplamp/BTSI switch in the non-ABS mode. The EBTCM looks for a deceleration rate that indicates braking action and requires several repeats of this detection method in order to verify this assumption. In each case, the TCS will not be available since the EBTCM detects no stoplamp/BTSI switch voltage.

Conditions for Setting the DTC

The stoplamp switch remains open for 3 deceleration cycles.

Action Taken When the DTC Sets

    • A malfunction DTC is stored.
    • The TCS is disabled.
    • The TRACTION CONTROL indicator is turned ON.
    • The ABS remains functional.

Conditions for Clearing the DTC

    • The condition for DTC is no longer present and you used scan tool Clear DTCs function.
    • The condition for DTC is no longer present and you used the On-Board Clear DTCs function.
    • The EBTCM does not detect the DTC in 50 drive cycles.

Diagnostic Aids

    • If any wheel speed sensor DTCs are present, diagnose them first. Refer to Diagnostic Trouble Code (DTC) List .
    • Thoroughly inspect the wiring and the connectors. Failure to carefully and fully inspect the wiring and the connectors may result in misdiagnosis. Misdiagnosis may cause part replacement with the reappearance of the malfunction.
    • An intermittent malfunction may be caused by a poor connection, 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.
    • This DTC may be caused by one of the following conditions:
       - An open stoplamp/BTSI switch
       - An open STOP Fuse
       - The stoplamp/BTSI switch is misadjusted.
       - Erratic wheel speeds
       - The circuit has a wiring problem, terminal corrosion, or poor connections.

Test Description

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

  1. This step checks if the stoplamp/BTSI switch and the power distribution are functional.

  2. This step checks for voltage at the EBTCM.

  3. This step checks the stoplamp/BTSI switch.

Step

Action

Value(s)

Yes

No

1

Did you perform the ABS Diagnostic System Check?

--

Go to Step 2

Go to Diagnostic System Check - ABS

2

Are any wheel speed sensor DTCs present?

--

Go to Diagnostic Trouble Code (DTC) List

Go to Step 3

3

Press the brake pedal.

Do the brake lights turn on?

--

Go to Step 4

Go to Step 7

4

  1. Turn OFF the ignition.
  2. Disconnect the EBTCM connector.
  3. Install the J 39700 universal pinout box using the J 39700-25 adapter cable to the EBTCM harness connector only.
  4. Turn ON the ignition, with the engine OFF.
  5. Press the brake pedal.
  6. Use a J 39200 DMM in order to measure the voltage at the J 39700 terminal 9.

Is the voltage within the specified range?

Battery Voltage

Go to Step 5

Go to Step 6

5

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

Did you complete the repair?

--

Go to Diagnostic System Check - ABS

--

6

Repair the open in CKT 20. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Diagnostic System Check - ABS

--

7

Inspect the underhood fuse block STOP LP Fuse.

Is the fuse good?

--

Go to Step 8

Go to Step 12

8

  1. Disconnect the stoplamp/BTSI switch connector C1.
  2. Use a J 39200 DMM in order to measure the voltage at the stoplamp/BTSI switch harness connector C1 terminal A .

Is the voltage within the specified range?

Battery Voltage

Go to Step 10

Go to Step 9

9

Repair the open in CKT 1540. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Diagnostic System Check - ABS

--

10

Connect a fused jumper wire between the stoplamp/BTSI switch harness connector C1 terminal A and terminal B.

Do the brake lamps turn on?

--

Go to Step 11

Go to Step 6

11

Adjust or repair the stoplamp/BTSI switch as necessary. Refer to Stop Lamp Switch Replacement or Stop Lamp Switch Adjustment in Hydraulic Brakes.

Did you complete the repair?

--

Go to Diagnostic System Check - ABS

--

12

  1. Replace the STOP LP Fuse in the underhood fuse block. Do not press the brake pedal.
  2. Inspect the STOP LP Fuse.

Is the fuse good?

--

Go to Step 14

Go to Step 13

13

Repair the short to ground in CKT 1540. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Diagnostic System Check - ABS

--

14

  1. Press the brake pedal.
  2. Inspect the STOP LP fuse.

Is the fuse good?

--

Go to Diagnostic System Check - ABS

Go to Step 15

15

  1. Turn OFF the ignition.
  2. Disconnect the EBTCM connector.
  3. Replace the fuse.
  4. Press the brake pedal.
  5. Inspect the STOP LP fuse.

Is the fuse good?

--

Go to Step 5

Go to Step 16

16

Repair the short to ground in CKT 20. Refer to Wiring Repairs in Wiring Systems.

Did you complete the repair?

--

Go to Diagnostic System Check - ABS

--