GM Service Manual Online
For 1990-2009 cars only

Object Number: 155212  Size: SF
ABS Components
Antilock Brake System Schematics
Power Distribution Schematics
OBD II Symbol Description Notice
Handling ESD Sensitive Parts Notice
Exterior Lights Schematics

Circuit Description

DTC C1294 determines the proper operation of the brake switch. Proper operation of the brake switch is important because the brake switch activates the ABS and inhibits the TCS when the brake switch is on. The brake switch deactivates the ABS when the brake switch is off. The following conditions always occur when the brake switch is on:

    • ABS operation is requested.
    • TCS operation is inhibited.

Conditions for Setting the DTC

DTC C1294 can set if the vehicle's speed is greater than 40 km/h (25 mph).

A malfunction exists if the brake was always on during two consecutive drive cycles.

Action Taken When the DTC Sets

    • A malfunction DTC stores.
    • ABS operation remains.
    • TCS operation is inhibited.

Conditions for Clearing the DTC

    • The condition responsible for setting the DTC no longer exists and the Scan Tool Clear DTC function is used.
    • 100 drive cycles pass with no DTC detected.

Diagnostic Aids

Use the enhanced diagnostic function of the Scan Tool in order to measure the frequency of the malfunction. Refer to the Scan Tool manual or Scan Tool Diagnostics located in this section for the procedure. Use the Data List of the Scan Tool verify proper brake switch operation. The Data List should display the brake switch as the brake is applied within 25 mm (1.0 in) of brake pedal travel.

Thoroughly inspect any circuitry that may cause the intermittent complaint for the following conditions:

    • Rubbed-through wire insulation
    • A broken wire inside the insulation
    • Backed out terminals
    • Improper mating
    • Broken locks
    • Improperly formed or damaged terminals
    • Poor terminal-to-wiring connections
    • Physical damage to the wiring harness

Important: Zero the J 39200 test leads before making any resistance measurements.

Step

Action

Value(s)

Yes

No

1

Was the Diagnostic System Check performed?

--

Go to Step 2

Go to Diagnostic System Check

2

  1. Turn the ignition switch to the OFF position.
  2. Verify that there is no pressure on the brake pedal.
  3. Observe the rear brake lamps.

Are the rear brake lamps on?

--

Go to Step 3

Go to Step 5

3

Disconnect the stoplamp switch connector C1.

Are the rear brake lamps on?

--

Go to Step 8

Go to Step 4

4

Inspect the adjustment of the stoplamp switch.

Is the stoplamp switch adjusted correctly?

--

Go to Step 10

Go to Step 9

5

  1. Disconnect the 24-way EBCM/EBTCM connector C1.
  2. Turn the ignition switch to the RUN position.
  3. , engine OFF.

  4. Use the J 39200 to measure the voltage at the 24-way EBCM/EBTCM connector C1 terminal B9.

Is the voltage equal to the specified value?

0.00V

Go to Step 6

Go to Step 8

6

  1. Turn the ignition switch to the OFF position.
  2. Inspect the 24-way EBCM/EBTCM connector C1 for the following conditions:
  3. • Terminal damage
    • Poor terminal contact
    • Terminal corrosion

Is there evidence of poor terminal contact, terminal corrosion, or damaged terminals?

--

Go to Step 11

Go to Step 7

7

  1. Reconnect the 24-way EBCM/EBTCM connector C1.
  2. Install a Scan Tool
  3. Start the engine.
  4. Test drive the vehicle, obtaining a speed at least 40 km/h (25 mph).
  5. Repeat the drive cycle, and steps 3, 4, and 5 at least two additional times.
  6. Use the Scan Tool to read the DTCs.

Does DTC C1294 set as a current DTC during the last three drive cycles?

--

Go to Step 12

Go to Step 13

8

Repair the short to voltage in CKT 17.

Is the repair complete?

--

Go to Diagnostic System Check

--

9

Adjust the stoplamp switch. Refer to Stoplamp Switch Adjustment .

Is the repair complete?

--

Go to Diagnostic System Check

--

10

Replace the stoplamp switch. Refer to Stoplamp Switch Replacement .

Is the repair complete?

--

Go to Diagnostic System Check

--

11

Replace all of the terminals and connectors that exhibit the following conditions:

    • Poor terminal contact
    • Corrosion
    • Damaged terminal(s)

Is the repair complete?

--

Go to Diagnostic System Check

--

12

Replace the EBCM/EBTCM. Refer to Electronic Brake and Traction Control Module Replacement .

Is the repair complete?

--

Go to Diagnostic System Check

--

13

The malfunction is intermittent or not present at this time.

Is a concern still present?

--

Go to Diagnostic Aids

Go to Diagnostic System Check