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Pinpoint Test I: DTC C1287




Anti-Lock Control

Pinpoint Tests

Pinpoint Test I: DTC C1287

Refer to Wiring Diagram Set 42, Vehicle Dynamic Systems for schematic and connector information. Diagrams By Number

Normal Operation

The active brake booster has a normally open and a normally closed pedal force switch that operates according to driver brake applications.

In the normally open position, the brake booster pedal force switch connects circuit CCA29 (GN/BU) to circuit CCA25 (VT/GY). In the normally closed position, the switch connects circuit CCA29 (GN/BU) to circuit CCA26 (BU/GY).

- DTC C1287 Brake Booster Pedal Force Switch Circuit Failure - If the ABS module detects an open, a short to voltage or a short to ground on the booster pedal force switch circuits, or if the switch input does not agree with other brake pedal inputs, DTC C1287 will be set.

This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Active brake booster
- ABS module



PINPOINT TEST I: DTC C1287

NOTICE: Use the Flex Probe Kit for all test connections to prevent damage to the wiring terminals. Do not use standard multi-meter probes.

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I1 CHECK THE DTCs FROM THE SELF-TEST


- Connect the scan tool.
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: Clear All CMDTCs.
- Enter the following diagnostic mode on the scan tool: Self Test - ABS Module .
- Retrieve and record any ABS module DTCs.
- Are any DTCs retrieved?

Yes
If DTC C1287 is retrieved GO to I2.

If any other DTC is retrieved, GO to the ABS Module DTC Chart. Diagnostic Trouble Code Tests and Associated Procedures

No
The system is operating correctly at this time.

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I2 CHECK THE BRAKE BOOSTER PEDAL FORCE SWITCH NORMALLY CLOSED POSITION


NOTE: To access C149, position the Battery Junction Box (BJB) aside.

- Ignition OFF.
- Disconnect: Active Brake Booster C149.
- Measure the resistance between active brake booster C149 pin-5 and pin-2, component side, while pressing and releasing the brake pedal.
- Is the resistance less than 5 ohms with the brake pedal released and greater than 10,000 ohms with the brake pedal applied?

Yes
GO to I3.

No
INSTALL a new active brake booster. REFER to Power Brake Assist. CLEAR the DTC. REPEAT the self-test.

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I3 CHECK THE BRAKE BOOSTER PEDAL FORCE SWITCH NORMALLY OPEN POSITION


- Measure the resistance between active brake booster C149 pin-5 and pin-1, component side, while pressing and releasing the brake pedal.
- Is the resistance greater than 10,000 ohms with the brake pedal released and less than 5 ohms with the brake pedal applied?

Yes
GO to I4.

No
INSTALL a new active brake booster. REFER to Power Brake Assist. CLEAR the DTC. REPEAT the self-test.

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I4 CHECK THE PEDAL FORCE SWITCH CIRCUITS FOR A SHORT TOGETHER


- Disconnect: ABS Module C155.
- Measure the resistance between:
- active brake booster C149-1, circuit CCA26 (BU/GY), harness side and active brake booster C149-2, circuit CCA25 (VT/GY), harness side.
- active brake booster C149-2, circuit CCA25 (VT/GY), harness side and active brake booster C149-5, circuit CCA29 (GN/BU), harness side.
- active brake booster C149-1, circuit CCA26 (BU/GY), harness side, and active brake booster C149-5, circuit CCA29 (GN/BU), harness side.




- Are the resistances greater than 10,000 ohms?

Yes
GO to I5.

No
REPAIR the affected circuit(s). CLEAR the DTCs. REPEAT the self-test.

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I5 CHECK THE PEDAL FORCE SWITCH CIRCUITS FOR A SHORT TO VOLTAGE


- Ignition ON.
- Measure the voltage between ground and:
- active brake booster C149-1, circuit CCA26 (BU/GY), harness side.
- active brake booster C149-2, circuit CCA25 (VT/GY), harness side.
- active brake booster C149-5, circuit CCA29 (GN/BU), harness side.




- Is any voltage present?

Yes
REPAIR the affected circuit(s). CLEAR the DTCs. REPEAT the self-test.

No
GO to I6.

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I6 CHECK THE PEDAL FORCE SWITCH CIRCUITS FOR A SHORT TO GROUND


- Ignition OFF.
- Measure the resistance between ground and:
- active brake booster C149-1, circuit CCA26 (BU/GY), harness side.
- active brake booster C149-2, circuit CCA25 (VT/GY), harness side.
- active brake booster C149-5, circuit CCA29 (GN/BU), harness side.




- Are the resistances greater than 10,000 ohms?

Yes
GO to I7.

No
REPAIR the affected circuit(s). CLEAR the DTCs. REPEAT the self-test.

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I7 CHECK THE PEDAL FORCE SWITCH CIRCUITS FOR AN OPEN


- Ignition OFF.
- Measure the resistance between the ABS module connector, harness side and the active brake booster connector, harness side as indicated in the following chart:









- Are the resistances less than 5 ohms?

Yes
GO to I8.

No
REPAIR the affected circuit(s) for an open. CLEAR the DTCs. REPEAT the self-test.

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I8 CHECK FOR CORRECT ABS MODULE OPERATION


- Check ABS module C155 for:
- corrosion.
- pushed-out pins.
- spread terminals.
- Connect: ABS Module C155.
- Make sure the connector seats correctly, then operate the system and verify the concern is still present.
- Is the concern still present?

Yes
INSTALL a new ABS module. REFER to Anti-Lock Brake System (ABS) Module Service and Repair. TEST the system for normal operation.

No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the self-test.

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