Pinpoint Test B: DTC P1572 Or DTC P1703
Speed Control
Pinpoint Test B: DTC P1572 or DTC P1703
Refer to Wiring Diagram Set 31, Speed 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 through circuit 1651 (WH/RD). 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 will release the throttle and disable the speed control system.
The speed control deactivator switch interrupts the power signal to the PCM through circuit 636 (OG) 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 speed 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
- Speed 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 Brake Lamp. 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 Antilock Brakes / Traction Control 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 SPEED 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 CIRCUIT 1119 (RD) FOR AN OPEN
- Disconnect: Speed Control Deactivator Switch C277.
- Measure the voltage between the speed 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. REPEAT the self-test.
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B6 CHECK CIRCUIT 636 (OG) FOR A SHORT TO VOLTAGE
- Ignition ON.
- Measure the voltage between the speed control deactivator switch C277-2, circuit 636 (OG), harness side and ground.
- Is any voltage present?
Yes
REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
No
GO to B7.
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B7 CHECK CIRCUIT 636 (OG) FOR AN OPEN
- Ignition OFF.
- Measure the resistance between the speed control deactivator switch C277-2, circuit 636 (OG), harness side and the PCM C175b-9, circuit 636 (OG), harness side.
- Is the resistance less than 5 ohms?
Yes
INSTALL a new speed control deactivator switch. REFER to Speed Control Deactivator Switch Speed Control Deactivator Switch. CLEAR the DTCs. REPEAT the self-test.
No
REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
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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. 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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