Pinpoint Test B: DTC P1703 Or DTC P1572 - Brake On/Off Circuit Failure
WARNING: This page is about a different car, the 2005 Ford Pickup, 2005 Ford F550 Super Duty, 2005 Ford F450 Super Duty, and 2005 Ford Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.
- B1 CHECK CIRCUIT 810 (RD/LG) FOR VOLTAGE
- Key in OFF position.
- Disconnect: Powertrain Control Module (PCM) C175b.
- Key in ON position.
- Measure the voltage between the PCM C175b-8, circuit 810 (RD/LG), harness side and ground.
- Is any voltage present?
- Yes : GO to B2.
- No : GO to B5.
- B2 CHECK THE STOPLAMP SWITCH
- Key in OFF position.
- Disconnect: Stoplamp Switch C278.
- Key in ON position.
- Measure the voltage between the PCM C175b-8, circuit 810 (RD/LG), harness side and ground.
- Is any voltage present?
- Yes
: If equipped with automatic transmission, GO to B3.
If equipped with four-wheel drive (4WD) manual transmission, GO to B4.
If equipped with two-wheel drive (2WD) manual transmission, GO to B5.
- No : INSTALL a new stoplamp switch. REFER to EXTERIOR LIGHTING . CLEAR the DTCs. REPEAT the self-test.
- B3 CHECK THE BRAKE SHIFT INTERLOCK ACTUATOR
- Key in OFF position.
- Disconnect: Brake Shift Interlock C2008.
- Key in ON position.
- Measure the voltage between the PCM C175b-8, circuit 810 (RD/LG), harness side and ground.
- Is any voltage present?
- Yes
: If equipped with 2WD transmission, REPAIR circuit 810 (RD/LG). CLEAR the DTCs. REPEAT the self-test.
If equipped with 4WD transmission, GO to B4.
- No : INSTALL a new brake shift interlock actuator. REFER to AUTOMATIC TRANSAXLE/TRANSMISSION - TORQSHIFT . CLEAR the DTCs. REPEAT the self-test.
- B4 CHECK THE 4WD CONTROL MODULE
- Key in OFF position.
- Disconnect: 4WD Control Module C281a.
- Key in ON position.
- Measure the voltage between the PCM C175b-8, circuit 810 (RD/LG), harness side and ground.
- Is any voltage present?
- Yes : REPAIR circuit 810 (RD/LG). CLEAR the DTCs. REPEAT the self-test.
- No : GO to B12.
- B5 CHECK THE BRAKE PEDAL STOPLAMP SWITCH FOR CORRECT OPERATION
- While applying the brake pedal, measure the voltage between the PCM C175b-8, circuit 810 (RD/LG), harness side and ground.
- Is the voltage greater than 10 volts?
- Yes : GO to B8.
- No : GO to B6.
- B6 CHECK CIRCUIT 22 (LB/BK) FOR AN OPEN
- Key in OFF position.
- Disconnect: Stoplamp Switch C278.
- Key in ON position.
- Measure the voltage between the stoplamp switch C278-3, circuit 22 (LB/BK), harness side and ground.
- Is the voltage greater than 10 volts?
- Yes : GO to B7.
- No : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
- B7 CHECK CIRCUIT 810 (RD/LG) FOR AN OPEN
- Key in OFF position.
- Measure the resistance between the stoplamp switch C278-4, circuit 810 (RD/LG), harness side and the PCM C175b-8, circuit 810 (RD/LG), harness side.
- Is the resistance less than 5 ohms?
- Yes : INSTALL a new stoplamp switch. REFER to EXTERIOR LIGHTING . CLEAR the DTCs. REPEAT the self-test.
- No : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
- B8 CHECK THE SPEED CONTROL DEACTIVATOR SWITCH FOR CORRECT OPERATION
- While firmly applying and releasing the brake pedal, measure the voltage between the PCM C175a-65, circuit 307 (BK/YE), harness side and ground.
- Is the voltage greater than 10 volts with the brake pedal released, and 0 volts with the brake pedal firmly applied?
- Yes : GO to B13.
- No : GO to B9.
- B9 CHECK CIRCUIT 418 (DG/YE) FOR AN OPEN
- Key in OFF position.
- Disconnect: Speed Control Deactivator Switch C1025.
- Key in ON position.
- Measure the voltage between the speed control deactivator switch C1025-2, circuit 418 (DG/YE), harness side and ground.
- Is the voltage greater than 10 volts?
- Yes : GO to B10.
- No : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
- B10 CHECK CIRCUIT 307 (BK/YE) FOR A SHORT TO VOLTAGE
- Measure the voltage between the speed control deactivator switch C1025-1, circuit 307 (BK/YE), harness side and ground.
- Is any voltage present?
- Yes : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
- No : GO to B11.
- B11 CHECK CIRCUIT 307 (BK/YE) FOR AN OPEN
- Key in OFF position.
- Measure the resistance between the speed control deactivator switch C1025-1, circuit 307 (BK/YE), harness side and the PCM C175a-65, circuit 307 (BK/YE), harness side.
- Is the resistance less than 5 ohms?
- Yes : INSTALL a new brake master cylinder. REFER to HYDRAULIC BRAKE ACTUATION . CLEAR the DTCs. REPEAT the self-test.
- No : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
- B12 CHECK FOR CORRECT 4WD CONTROL MODULE OPERATION
- Disconnect all the 4WD control module connectors.
- Check for:
- corrosion
- pushed-out pins
- Connect all the 4WD control module connectors and make sure they are seated correctly.
- Operate the system and verify the concern is still present.
- Is the concern still present?
- Yes : INSTALL a new 4WD control module. REFER to FOUR- WHEEL DRIVE SYSTEMS .
- 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.
- B13 CHECK FOR CORRECT PCM OPERATION
- Disconnect all the PCM connectors.
- Check for:
- corrosion
- pushed-out pins
- Connect all the PCM connectors and make sure they are seated correctly.
- Operate the system and verify the concern is still present.
- Is the concern still present?
- Yes : INSTALL a new PCM. REFER to ELECTRONIC ENGINE CONTROLS - GASOLINE ENGINES .
- 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.