Pinpoint Test B: DTC P0572, P0573 Or P1703
Cruise Control
Pinpoint Tests
Pinpoint Test B: DTC P0572, P0573 Or P1703
Refer to Wiring Diagram Set 31 (Fusion/Milan/MKZ, Fusion Hybrid/Milan Hybrid), Speed Control for schematic and connector information. Diagrams By Number
Normal Operation
When the brake pedal is applied, the normally open stoplamp switch closes and sends a voltage to the PCM disengaging the cruise control.
The normally closed cruise control deactivator switch (part of the stoplamp switch), opens and removes the voltage signal to the PCM when the brake pedal is applied firmly. This is a redundant cruise control deactivation signal to the PCM.
- DTC P0572 (Brake Switch A Circuit Low) - sets when the PCM senses a short to ground in the stoplamp switch circuits.
- DTC P0573 (Brake Switch A Circuit High) - sets when the PCM senses a open or a short to voltage in the stoplamp switch circuits.
- DTC P1703 (Brake Switch Out Of Self Test Range) - sets when there is an open or short in the deactivator switch circuits or when there is an open or short in the stoplamp circuits when the PCM self test is carried out.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Cruise control deactivator switch (integral to the stoplamp switch)
- ABS module
- PCM
PINPOINT TEST B: DTC P0572, P0573 OR P1703
NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.
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B1 CHECK THE OPERATION OF THE STOPLAMPS
- Ignition ON.
- Operate the stoplamps.
- Do the stoplamps operate correctly?
Yes
GO to B2.
No
REFER to Lighting and Horns to continue diagnosis of the stoplamps.
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B2 CHECK FOR ABS DTCs
- Review the recorded DTCs from the ABS self-test.
- Are any DTCs recorded?
Yes
REFER to Antilock Brakes / Traction Control Systems. REPAIR all ABS module DTCs and RETEST the cruise control.
No
For 3.5L engines, GO to B3.
Otherwise, GO to B4.
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B3 CHECK THE STOPLAMP SWITCH (BOO AND BPA) PIDs
- Enter the following diagnostic mode on the scan tool: PCM DataLogger.
- Monitor the PCM PIDs BOO (brake pedal top travel) and BPA (brake pedal bottom travel) while applying and releasing the brake pedal as follows:
- Do the PID values agree with the brake pedal position?
Yes
GO to B9.
No
For an incorrect BOO1 PID value, GO to B5.
If the BOO2 PID value reads On, GO to B7.
If the BOO2 PID value reads OFF, GO to B6.
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B4 CHECK THE STOPLAMP SWITCH (BOO1 AND BOO2) PIDs
- Enter the following diagnostic mode on the scan tool: PCM DataLogger.
- Monitor the PCM PIDs BOO1 (brake pedal top travel) and BOO2 (brake pedal bottom travel) while applying and releasing the brake pedal as follows:
- Do the PID values agree with the brake pedal position?
Yes
GO to B9.
No
For an incorrect BOO1 PID value, GO to B5.
If the BOO2 PID value reads On, GO to B7.
If the BOO2 PID value reads OFF, GO to B6.
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B5 CHECK THE STOPLAMP SWITCH CIRCUIT FOR VOLTAGE
- Ignition OFF.
- Disconnect: PCM C175b.
- Ignition ON.
- For vehicles with 2.5L and 3.0L engines, while applying the brake pedal, measure the voltage between the PCM C175b-13, circuit CCB08 (VT/WH), harness side and ground.
- For vehicles with 3.5L engines, while applying the brake pedal, measure the voltage between the PCM C175b-46, circuit CCB08 (VT/WH), harness side and ground.
- Is the voltage greater than 10 volts with the brake pedal applied and 0 volts with the brake pedal released?
Yes
GO to B9.
No
REPAIR the circuit for an open. CLEAR the DTCs. TEST the system for normal operations.
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B6 CHECK THE CRUISE CONTROL DEACTIVATOR SWITCH CIRCUIT FOR A SHORT TO VOLTAGE
- Disconnect: Stoplamp Switch C278.
- Measure the voltage between the stoplamp switch C278-3, circuit CES09 (VT/OG), harness side and ground.
- Is any voltage present?
Yes
REPAIR the circuit. CLEAR the DTCs. TEST the system for normal operations.
No
INSTALL a new stoplamp switch. CLEAR the DTCs. TEST the system for normal operations.
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B7 CHECK THE CRUISE CONTROL DEACTIVATOR SWITCH VOLTAGE SUPPLY CIRCUIT FOR AN OPEN
- Disconnect: Stoplamp Switch C278.
- Measure the voltage between the stoplamp switch C278-2, circuit CBK02 (GN), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to B8.
No
REPAIR the circuit. CLEAR the DTCs. TEST the system for normal operations.
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B8 CHECK THE CRUISE CONTROL DEACTIVATOR SWITCH CIRCUIT FOR AN OPEN
- Ignition OFF.
- Disconnect: PCM C175b.
- For vehicles with 2.5L and 3.0L engines, measure the resistance between the PCM C175b-46, circuit CES09 (VT/OG), harness side and the stoplamp switch C278-3, circuit CES09 (VT/OG), harness side.
- For vehicles with 3.5L engines, measure the resistance between the PCM C175b-47, circuit CES09 (VT/OG), harness side and the stoplamp switch C278-3, circuit CES09 (VT/OG), harness side.
- Is the resistance less than 5 ohms?
Yes
INSTALL a new stoplamp switch. CLEAR the DTCs. TEST the system for normal operations.
No
REPAIR the circuit. CLEAR the DTCs. TEST the system for normal operations.
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B9 CHECK FOR CORRECT PCM OPERATION
- Disconnect all the PCM connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the PCM 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 PCM. REFER to Computers and Control Systems. 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.
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