Pinpoint Test B: DTC P1572 OR DTC P1703
Cruise Control
Pinpoint Tests
Pinpoint Test B: DTC P1572 OR DTC P1703
Refer to Wiring Diagram Set 31, Cruise Control for schematic and connector information. Diagrams By Number
Normal Operation
When the brake pedal is applied, voltage is sent to the ABS module from the stoplamp switch. The PCM receives a serial message from the ABS module over the High Speed Controller Area Network (HS-CAN), indicating the brake pedal has been applied. The PCM releases the throttle and disable the cruise control system.
The cruise control deactivator switch interrupts the power signal to the PCM when the brake pedal is applied firmly. This is a redundant signal to the PCM.
- DTC P1572 (Brake Pedal Switch Circuit) - sets when the PCM does not sense the correct sequence of the brake pedal input signal from both the cruise control deactivator and stoplamp switches when the brake pedal is pressed and released.
- 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.
This pinpoint test is intended to diagnose the following:
- Fuse
- Wiring, terminals or connectors
- Stoplamp switch
- Cruise control deactivator switch
- PCM
PINPOINT TEST B: DTC P1572 OR DTC 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 Exterior Lighting Testing and Inspection.
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B2 CHECK THE STOPLAMP SWITCH (BOO_ABS) PID
- Enter the following diagnostic mode on the scan tool: ABS Module DataLogger.
- Monitor the ABS module PID (BOO_ABS).
- Apply and release the brake pedal.
- Does the PID values display OFF with the brake pedal released and ON with the brake pedal applied?
Yes
GO to B3.
No
REFER to Vehicle Dynamic Systems Testing and Inspection.
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B3 CHECK THE STOPLAMP SWITCH (BOO) AND BRAKE PRESSURE SWITCH (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 pressure switch) while applying and releasing the brake pedal as follows:
- Do the PID values agree with the brake pedal position?
Yes
GO to B8.
No
GO to B4.
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B4 CHECK THE CRUISE CONTROL DEACTIVATOR SWITCH FOR CORRECT OPERATION
- Ignition OFF.
- Disconnect: PCM C175b.
- While firmly applying and releasing the brake pedal, measure the voltage between the PCM C175b-9, circuit 636 (OG), 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 B8.
No
GO to B5.
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B5 CHECK THE CRUISE CONTROL DEACTIVATOR SWITCH CIRCUIT FOR AN OPEN
- Disconnect: Cruise Control Deactivator Switch C277.
- Measure the voltage between the cruise control deactivator switch C277-1, circuit 1119 (RD), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to B6.
No
REPAIR the circuit. CLEAR the DTCs. TEST the system for normal operation.
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B6 CHECK THE CRUISE CONTROL DEACTIVATOR SWITCH CIRCUIT FOR A SHORT TO VOLTAGE
- Ignition ON.
- Measure the voltage between the cruise control deactivator switch C277-2, circuit 636 (OG), harness side and ground.
- Is any voltage present?
Yes
REPAIR the circuit. CLEAR the DTCs. TEST the system for normal operation.
No
GO to B7.
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B7 CHECK THE CRUISE CONTROL DEACTIVATOR SWITCH CIRCUIT FOR AN OPEN
- Ignition OFF.
- Measure the resistance between the PCM C175b-9, circuit 636 (OG), harness side and the cruise control deactivator switch C277-2, circuit 636 (OG), harness side.
- Is the resistance less than 5 ohms?
Yes
INSTALL a new cruise control deactivator switch. REFER to Cruise Control Deactivator Switch Cruise Control Deactivator Switch. CLEAR the DTCs. TEST the system for normal operation.
No
REPAIR the circuit. CLEAR the DTCs. TEST the system for normal operation.
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B8 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 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 Service and Repair. 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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