Pinpoint Test J: DTC C1287 - Brake Booster Pedal Force Switch Circuit Failure: Overview

WARNING: This page is about a different car, the 2004 Mercury Mountaineer and 2004 Ford Explorer. 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 RECALIBRATION PROCEDURE
- Key in ON position.
- Enter the following diagnostic mode on the diagnostic tool: Clear DTCs.
- Carry out the active 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 recalibration procedure indicates a fault, GO to J2.

If any other DTC, GO to the ABS MODULE DIAGNOSTIC TROUBLE CODE (DTC) INDEX .

No

The system is operating correctly.
J2 CHECK THE NORMALLY CLOSED RELEASE SWITCH
- Key in OFF position.
- Disconnect: Active Brake Booster C149.
- Measure the resistance between the active brake booster C149-2, circuit 1580 (WH/LG), component side and the active brake booster C149-5, circuit 1579 (OG/RD), component side, while pressing and releasing the brake pedal.
  
  Fig 1: Measuring Resistance Between Active Brake Booster C149-2, Circuit 1580 (WH/LG)
  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 active brake booster. REFER to BRAKE SYSTEM-GENERAL INFORMATION . CLEAR the DTCs. RECALIBRATE the ABS module. FOLLOW the diagnostic tool directions for the calibration procedure. REPEAT the self-test.
J3 CHECK THE NORMALLY OPEN RELEASE SWITCH
- Measure the resistance between the active brake booster C149-1, circuit 1581 (PK/LB), component side and the active brake booster C149-5, circuit 1579 (OG/RD), component side, while pressing and releasing the brake pedal.
  
  Fig 2: Measuring Resistance Between Active Brake Booster C149-1, Circuit 1581 (PK/LB)
  Courtesy of FORD MOTOR CO.
- 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 J4.

No

INSTALL a new active brake booster. REFER to BRAKE SYSTEM-GENERAL INFORMATION . CLEAR the DTCs. RECALIBRATE the ABS module. FOLLOW the diagnostic tool directions for the calibration procedure. REPEAT the self-test.

J4 CHECK THE ACTIVE BRAKE BOOSTER CIRCUITRY FOR A SHORT

Disconnect: ABS Module C155.

Measure the resistance between the active brake booster connector pins, harness side as follows:

CIRCUIT SPECIFICATION

Active Brake Booster Connector-Pin	Circuit
C149-1	1581 (PK/LB)
C149-2	1580 (WH/LG)
C149-5	1579 (OG/RD)

Fig 3: Measuring Resistance Between Active Brake Booster Connector Pins, Harness Side

Courtesy of FORD MOTOR CO.

Are the resistances greater than 10,000 ohms?

Yes

GO to J5.

REPAIR the circuit(s) in question. CLEAR the DTCs. RECALIBRATE the ABS module. REPEAT the self-test.

J5 CHECK THE ACTIVE BRAKE BOOSTER CIRCUITRY FOR A SHORT TO POWER

Key in ON position.

Measure the voltage between the active brake booster connector, harness side and ground as follows:

CIRCUIT SPECIFICATION

Active Brake Booster Connector-Pin	Circuit
C149-1	1581 (PK/LB)
C149-2	1580 (WH/LG)
C149-5	1579 (OG/RD)

Fig 4: Measuring Voltage Between Active Brake Booster Connector, Harness Side And Ground

Courtesy of FORD MOTOR CO.

Is any voltage present?

Yes

REPAIR the circuit(s) in question. CLEAR the DTCs. RECALIBRATE the ABS module. REPEAT the self-test.

GO to J6.

J6 CHECK THE ACTIVE BRAKE BOOSTER CIRCUITRY FOR SHORTS TO GROUND

Measure the resistance between the active brake booster connector, harness side and ground as follows:

CIRCUIT SPECIFICATION

Active Brake Booster Connector-Pin	Circuit
C149-1	1581 (PK/LB)
C149-2	1580 (WH/LG)
C149-5	1579 (OG/RD)

Fig 5: Measuring Resistance Between Active Brake Booster Connector, Harness Side And Ground

Courtesy of FORD MOTOR CO.

Are the resistances greater than 10,000 ohms?

Yes

GO to J7.

REPAIR the circuit(s) in question. CLEAR the DTCs. REPEAT the self-test.

J7 CHECK THE BRAKE BOOSTER CIRCUITRY FOR OPENS

Key in OFF position.

Measure the resistance between the ABS module connector, harness side and the active brake booster connector, harness side as follows:

CIRCUIT SPECIFICATION

ABS Module Connector-Pin	Active Brake Booster Connector-Pin	Circuit
C155-27	C149-1	1581 (PK/LB)
C155-28	C149-5	1579 (OG/RD)
C155-30	C149-2	1580 (WH/LG)

Fig 6: Measuring Resistance Between ABS Module Connector, Harness Side And Active Brake Booster Connector

Courtesy of FORD MOTOR CO.

Are the resistances less than 5 ohms?

Yes

GO to J8.

REPAIR the circuit(s) in question. CLEAR the DTCs. RECALIBRATE the ABS module. FOLLOW the diagnostic tool directions for the calibration procedure. REPEAT the self-test.

J8 CHECK FOR CORRECT ABS MODULE OPERATION
- Disconnect all ABS connectors.
- Check for:
  - corrosion
  - pushed-out pins
- Connect all ABS connectors and make sure they seat correctly.
- 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 . TEST the system for normal operation.

No

The system is operating correctly at this time. Concern may have been caused by a loose or corroded connector. CLEAR the DTCs. REPEAT the self -test.