Pinpoint Test B: DTC P1703 Or DTC P1572 - Brake On/Off Circuit Failure

WARNING: This page is about a different car, the 2005 Ford RV Cutaway, 2005 Ford Econoline, 2005 Ford E450 Super Duty, and 2005 Ford Cutaway. However, it is still accessible from the selected car via links, so may be relevant.

B1 CHECK THE STOPLAMP OPERATION
- Apply and release the brake pedal while observing the stoplamps.
- Do the stoplamps operate correctly?
- Yes : GO to B2.
- No : REFER to EXTERIOR LIGHTING to continue diagnosis of the stoplamps.
B2 CHECK CIRCUIT 569 (DG) FOR AN OPEN
- Key in OFF position.
- Disconnect: Powertrain Control Module (PCM) C175b.
- Measure the voltage between the PCM C175b-8, circuit 569 (DG), harness side and ground while applying the brake pedal.
  
  Fig 1: Measuring Voltage Between Control Module Connector And Ground
  Courtesy of FORD MOTOR CO.
- Is the voltage greater than 10 volts?
- Yes : GO to B3.
- No : REPAIR the circuit. CLEAR the DTCs. TEST the system for normal operation.
B3 CHECK THE SPEED CONTROL DEACTIVATOR SWITCH FOR CORRECT OPERATION
- Disconnect: PCM C175t.
- Key in ON position.
- While firmly applying and releasing the brake pedal, measure the voltage between the PCM C175t-65, circuit 307 (BK/YE), harness side and ground.
  
  Fig 2: Checking Speed Control Deactivator Switch
  Courtesy of FORD MOTOR CO.
- Is the voltage greater than 10 volts with the brake pedal released, and 0 volts with the brake pedal firmly applied?
- Yes : GO to B7.
- No : GO to B4.
B4 CHECK CIRCUIT 547 (LG/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 pin 2, circuit 547 (LG/YE), harness side and ground.
  
  Fig 3: Measuring Voltage Between Speed Control Deactivator Switch Pin 2 And Ground
  Courtesy of FORD MOTOR CO.
- Is the voltage greater than 10 volts?
- Yes : GO to B5.
- No : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
B5 CHECK CIRCUIT 307 (BK/YE) FOR A SHORT TO VOLTAGE
- Measure the voltage between the speed control deactivator switch C277-1, circuit 307 (BK/YE), harness side and ground.
  
  Fig 4: Measuring Voltage Between Speed Control Deactivator Switch Circuit 307 And Ground
  Courtesy of FORD MOTOR CO.
- Is any voltage present?
- Yes : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
- No : GO to B6.
B6 CHECK CIRCUIT 307 (BK/YE) FOR AN OPEN
- Key in OFF position.
- Measure the resistance between the PCM C175t-65, circuit 307 (BK/YE), harness side, and the speed control deactivator switch C277-1, circuit 307 (BK/YE), harness side.
  
  Fig 5: Measuring Resistance Between Circuit 307 And Speed Control Deactivator Switch For An Open Circuit
  Courtesy of FORD MOTOR CO.
- Is the resistance less than 5 ohms?
- Yes : INSTALL a new speed control deactivator switch. REFER to SPEED CONTROL DEACTIVATOR SWITCH . CLEAR the DTCs. REPEAT the self-test.
- No : REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
B7 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.