Cruise Control

Cruise Control

Pinpoint Test B: DTC P0504, P0572 Or P0573

Refer to Wiring Diagram Set 31, Cruise Control for schematic and connector information [1][2]Diagrams By Number.

Normal Operation

The stoplamp switch is a single plunger 2 stage switch with 2 inputs to the PCM. When the brake pedal is applied, the first stage, which is a normally open stoplamp switch, closes and sends a voltage signal to the PCM deactivating the cruise control, if engaged. The second stage is the normally closed cruise control deactivator switch (integral to the stoplamp switch) opens and removes the ground signal to the PCM when the brake pedal is firmly applied. This is a redundant signal to the PCM. There is less than one millimeter in plunger travel between the first and second stage which the PCM monitors.

- DTC P0504 (Brake Switch A / B Correlation)- 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 P0572 (Brake Switch A Circuit Low)- sets when the PCM detects an open in the stoplamp switch signal. The PCM monitors the vehicle speed, the engine speed, the engine torque and the stoplamp BOO input during start and stop driving cycles. If the BOO input to the PCM is always off during start and stop driving cycles this DTC sets in continuous memory.

- DTC P0573 (Brake Switch A Circuit High)- sets when the PCM detects an short to voltage on the stoplamp switch signal. The PCM monitors the vehicle speed, the engine speed, the engine torque and the stoplamp BOO input during start and stop driving cycles. If the BOO input to the PCM is always on during start and stop driving cycles this DTC sets in continuous memory.

This pinpoint test is intended to diagnose the following:

- Wiring, terminals or connectors

- Cruise control deactivator switch (integral to the stoplamp switch)

- Stoplamp switch

- PCM

PINPOINT TEST B : DTC P0504, P0572 OR P0573

NOTICE: Use the correct probe adapter(s) when making measurements. Failure to use the correct probe adapter(s) may damage the connector.

NOTE: Failure to disconnect the battery when instructed will result in false resistance readings.

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.

B2 CHECK THE STOPLAMP SWITCH (BOO1) AND CRUISE CONTROL DEACTIVATOR SWITCH (BOO2) PIDs

- Enter the following diagnostic mode on the scan tool: PCM DataLogger.

- Monitor the PCM PIDs BOO1 (stoplamp switch) and BOO2 (cruise control deactivator switch) while applying and releasing the brake pedal as follows:

Brake Pedal Position BOO1 PID BOO2 PID Released Off Off Applied lightly On Off Applied firmly On On

Do the PID values agree with the brake pedal position?

Yes
GO to B7.

No
For an incorrect BOO1 PID value, GO to B3.

For an incorrect BOO2 PID value, GO to B4.

B3 CHECK THE STOPLAMP INPUT TO THE PCM

- Ignition OFF.

- Disconnect: PCM C175B.

- Ignition ON.

- While applying the brake pedal, measure the voltage between the PCM C175B-13, circuit CCB08 (VT/WH), harness side and ground.





Is the voltage greater than 10 volts with the brake pedal applied?

Yes
GO to B7.

No
REPAIR the circuit for an open. CLEAR the DTCs. TEST the system for normal operation.

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 resistance between the PCM C175B-46, circuit CE509 (YE/GN), harness side and ground.





Is the resistance less than 5 ohms with the brake pedal released, and greater than 10,000 ohms with the brake pedal firmly applied?

Yes
GO to B7.

No
GO to B5.

B5 CHECK THE CRUISE CONTROL DEACTIVATOR SWITCH GROUND CIRCUIT FOR AN OPEN

- Disconnect: Stoplamp Switch C278.

- Disconnect: Negative Battery Cable.

- Measure the resistance between the stoplamp switch C278-2, circuit GD119 (BK), harness side and ground.





Is the resistance less than 5 ohms?

Yes
GO to B6.

No
REPAIR the circuit for an open. CLEAR the DTCs. TEST the system for normal operation.

B6 CHECK THE CRUISE CONTROL DEACTIVATOR SWITCH SIGNAL CIRCUIT FOR AN OPEN

- Connect a fused jumper wire between the stoplamp switch C278-3, circuit CE509 (YE/GN) , harness side and the stoplamp switch C278-2, circuit GD119 (BK), harness side.





- Measure the resistance between the PCM C175B-46, circuit CE509 (YE/GN), harness side and ground.





Is the resistance less than 5 ohms?

Yes
INSTALL a new stoplamp switch. CLEAR the DTCs. TEST the system for normal operation.

No
REPAIR circuit CE509 (YE/GN) for an open. CLEAR the DTCs. TEST the system for normal operation.

B7 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. 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. CLEAR the DTCs. REPEAT the self-test.