GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Oldsmobile 🢒 1998 🢒 Cutlass 🢒 Brakes 🢒 Hydraulic Brakes 🢒 Brake Warning Indicator Inoperative

Object Number: 445253 Size: MF
Hydraulic Brakes Components
Brake Warning System Schematics

Circuit Description

The BRAKE warning indicator has 2 functions. First, the indicator lights whenever the park brake is set. The body control module (BCM) commands the indicator on via serial data communication with the instrument cluster. Second, a switch built into the brake master cylinder reservoir signals the electronic brake control module (EBCM) if the brake fluid level drops below a safe level. The BCM then commands the indicator on via serial data communication with the instrument cluster. In addition, the indicator is commanded on when the EBCM is initially powered up (the ignition switch is turned to the ON position).

Diagnostic Aids

The following conditions activate the brake warning indicator:

    • The parking brake is applied while the ignition switch is in the ON position
    • A low fluid level in the master cylinder

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

    • Backed-out terminals
    • Improper mating
    • Broken locks
    • Improperly formed or damaged terminals
    • Faulty terminal-to-wiring connections
    • Physical damage to the wiring harness

Test Description

  1. This test determines if the malfunction is caused by the IPC.

    2.

  2. This test checks for an open in the EBCM serial data circuit.

    3.

  3. This test determines if the malfunction is caused by the brake fluid level sensor.

    4.

  4. This test checks for an open or high resistance in the brake fluid level sensor ground circuit.

    5.

  5. This test checks for an open or high resistance in the brake fluid level sensor input circuit.

    6.

  6. This test determines if the malfunction is caused by the park brake switch.

    7.

  7. This test checks for an open or high resistance in the park brake switch input circuit.

Step

Action

Value(s)

Yes

No

Important: Zero the J 39200 test leads before making any resistance measurements. Refer to the J 39200 user's manual.

1

Was the Brake Warning System Check performed?

--

Go to Step 2

Go to Brake Warning System Check

2

  1. Turn the ignition switch to the OFF position.
  2. Connect a Scan Tool .
  3. Turn the ignition switch to the RUN position.
  4. Select the Body menu then IPC on the Scan Tool .
  5. Select Special Functions then Lamp Test on the Scan Tool .
  6. Use the Scan Tool in order to turn the warning indicators ON.

Did the BRAKE warning indicator turn ON?

--

Go to Step 3

Go to Diagnostic System Check - Instrument Cluster in Instrument Panel, Gauges and Console

3

  1. Select the Chassis application on the Scan Tool .
  2. Select Data Display then ABS Data on the Scan Tool .

Is data being received from the EBCM?

--

Go to Step 4

Go to Diagnostic System Check in Antilock Brake Systems

4

Apply the parking brake.

Does the BRAKE warning indicator turn ON?

--

Go to Step 5

Go to Step 9

5

  1. Disconnect the brake fluid level sensor connector.
  2. Connect a fused jumper wire between the brake fluid level sensor connector terminals A and B.

Does the BRAKE warning indicator turn ON?

--

Go to Step 12

Go to Step 6

6

Use the J 39200 in order to measure the resistance between the brake fluid level sensor connector terminal A and ground.

Is the resistance within the specified range?

0-2 ohms

Go to Step 7

Go to Step 13

7

  1. Disconnect the EBCM connector C2.
  2. Use the J 39200 in order to measure the resistance between the EBCM connector C2 terminal B5 and the brake fluid level sensor connector terminal B.

Is the resistance within the specified range?

0-2 ohms

Go to Step 8

Go to Step 14

8
  1. Inspect the following components:
    2. • The EBCM connector C2
    • The brake fluid level sensor connector
  2. Inspect the components for the following conditions:
    3. • Poor terminal contact
    • Terminal corrosion
    • Damaged terminals

Are there signs of poor terminal contact, terminal corrosion or damaged terminals?

--

Go to Step 15

Go to Step 16

9

  1. Disconnect the park brake switch connector
  2. Connect a jumper wire between the park brake switch harness connector and ground.

Does the BRAKE warning indicator turn ON?

--

Go to Step 17

Go to Step 10

10

  1. Disconnect the IPC connector C1.
  2. Use the J 39200 in order to measure the resistance between the IPC connector C1 terminal B11 (Pontiac) or B12 (Chevrolet) and the park brake switch harness connector.

Is the resistance within the specified range?

0-2 ohms

Go to Step 11

Go to Step 18

11
  1. Inspect the following components:
    2. • The IPC connector C1
    • The park brake switch connector
  2. Inspect the components for the following conditions:
    3. • Poor terminal contact
    • Terminal corrosion
    • Damaged terminals

Are there signs of poor terminal contact, terminal corrosion or damaged terminals?

--

Go to Step 15

Go to Diagnostic System Check - Instrument Cluster in Instrument Panel, Gauges and Console

12

Replace the brake fluid level sensor. Refer to Brake Fluid Level Indicator Switch Replacement .

Is the repair complete?

--

Go to Brake Warning System Check

--

13

Repair the open or high resistance in CKT 251.

Is the repair complete?

--

Go to Brake Warning System Check

--

14

Repair the open or high resistance in CKT 849.

Is the repair complete?

--

Go to Brake Warning System Check

--

15

Replace the terminals or the connectors that exhibit the following conditions:

    • Poor terminal contact
    • Terminal corrosion
    • Damaged terminals

Is the repair complete?

--

Go to Brake Warning System Check

--

16

Replace the EBCM. Refer to Electronic Brake Control Module Replacement in Antilock Brakes.

Is the repair complete?

--

Go to Brake Warning System Check

--

17

Replace the park brake switch.

Is the repair complete?

--

Go to Brake Warning System Check

--

18

Repair open or high resistance in CKT 1134.

Is the repair complete?

--

Go to Brake Warning System Check

--