Pinpoint Test J: DTC C1287 - BRAKE BOOSTER PEDAL FORCE SWITCH CIRCUIT FAILURE

WARNING: This page is about a different car, the 2005 Lincoln LS. However, it is still accessible from the selected car via links, so may be relevant.

CAUTION: Use the Flex Probe Kit for all test connections to prevent damage to the wiring terminals. Do not use standard multimeter probes.

J1 CARRY OUT THE BRAKE BOOSTER RECALIBRATION PROCEDURE
- Key in ON position.
- Enter the following diagnostic mode on the diagnostic tool: Clear DTCs.
- Carry out the brake booster recalibration procedure using the diagnostic tool.
- Enter the following diagnostic mode on the diagnostic tool: Retrieve DTCs.
- Are any DTCs retrieved or does the recalibration procedure indicate a fault?
- Yes : If DTC C1287 is retrieved or the recalibration procedure indicates a fault, GO to J2.
  If any other DTC, GO to the ABS (WITH OR WITHOUT ADVANCE TRAC®/IVD) MODULE DIAGNOSTIC TROUBLE CODE (DTC) INDEX .
- No : The system is operating correctly.
J2 CHECK THE NORMALLY CLOSED RELEASE SWITCH
- Key in OFF position.
- Disconnect: Brake Booster C149.
- Measure the resistance between brake booster C149-2, component side and brake booster C149-5, component side, while applying and releasing the brake pedal.
  
  Fig 1: Measuring Resistance Between Brake Booster C149-2 And Brake Booster C149-5, Component Side
  Courtesy of FORD MOTOR CO.
- 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 J3.
- No : INSTALL a new brake booster. REFER to POWER BRAKE ACTUATION . CLEAR the DTC. RECALIBRATE the ABS module. FOLLOW the diagnostic tool directions for the calibration procedure. REFER to MODULE CONFIGURATION . REPEAT the self-test.
J3 CHECK THE NORMALLY OPEN RELEASE SWITCH
- Measure the resistance between brake booster C149-1, component side and brake booster C149-5, component side, while applying and releasing the brake pedal.
  
  Fig 2: Measuring Resistance Between Brake Booster C149-1 And Brake Booster C149-5, Component Side
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms with the brake pedal applied and greater than 10,000 ohms with the brake pedal released?
- Yes : GO to J4.
- No : INSTALL a new brake booster. REFER to POWER BRAKE ACTUATION . CLEAR the DTC. RECALIBRATE the ABS module. FOLLOW the diagnostic tool directions for the calibration procedure. REFER to MODULE CONFIGURATION . REPEAT the self-test.

J4 CHECK THE BRAKE BOOSTER CIRCUITRY FOR A SHORT TO VOLTAGE

Disconnect ABS Module C155
Key in ON position.

Measure the voltage between brake booster C149 pins, harness side and ground, as follows:

Active Brake Booster C149	Circuit
1	8-CF51 (WH/GN)
2	10-CF51 (GY/OG)
5	9-CF51 (BN/RD)

Is voltage present?

Yes : REPAIR the circuit in question. CLEAR the DTC. RECALIBRATE the ABS module. REPEAT the self-test.
No : GO to J5.

J5 CHECK THE BRAKE BOOSTER CIRCUITRY FOR A SHORT TO GROUND

Measure the resistance between brake booster C149 pins and ground as follows:

Brake Booster Pin	Circuit
1	8-CF51 (WH/GN)
2	10-CF51 (GY/OG)
5	9-CF51 (BN/GN)

Is the resistance greater than 10,000 ohms?

Yes : GO to J6.
No : REPAIR the circuit in question. CLEAR the DTC(s). REPEAT the self-test.

J6 CHECK THE BRAKE BOOSTER CIRCUITRY FOR AN OPEN

Key in OFF position.

Measure the resistance between ABS module C156 pins, harness side and brake booster C1499 pins, harness side as follows:

ABS Module C155 Pin	Brake Booster C149 Pin	Circuit
27	1	8-CF51 (WH/GN)
28	5	9-CF51 (BN/GN)
30	2	10-CF51 (GY/OG)

Are the resistances less than 5 ohms?

Yes : INSTALL a new ABS module. REFER to ANTI-LOCK BRAKE SYSTEM (ABS) MODULE in this article . REPEAT the self-test.
No : REPAIR the circuit in question. CLEAR the DTC. RECALIBRATE the ABS module. FOLLOW the diagnostic tool directions for the calibration procedure. REFER to MODULE COMMUNICATIONS NETWORK . REPEAT the self-test.