Pinpoint Test B: DTC P1572 or DTC P1703
Speed Control
Pinpoint Tests
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 PCM from the stoplamp switch through circuit CCB08 (VT/WH).
The speed control deactivator switch (part of the stoplamp switch) interrupts circuit CES09 (VT/OG) removing the voltage signal to the PCM when the brake pedal is applied firmly and passes the speed control deactivator switch point. This is a redundant signal to the PCM.
- DTC P1572 (Brake Pedal Switch Circuit) - sets when the PCM does not sense the proper 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:
- Wiring, terminals or connectors
- Speed control deactivator switch (integral to the stoplamp switch)
- ABS module
- 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 to continue diagnosis of the stoplamps. Testing and Inspection
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B2 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 B8.
No
For an incorrect BOO PID value, GO to B3.
For an incorrect BPA PID value, GO to B4.
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B3 CHECK CIRCUIT CCB08 (VT/WH) FOR VOLTAGE
- Ignition OFF.
- Disconnect: PCM C175b.
- Ignition ON.
- 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?
Yes
GO to B8.
No
REPAIR the circuit for an open. CLEAR the DTCs. REPEAT the self-test.
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B4 CHECK CIRCUIT CBP49 (VT/GY) FOR AN OPEN
- Disconnect: Stoplamp Switch C278.
- Measure the voltage between the stoplamp switch C278-2, circuit CBP49 (VT/GY), harness side and ground.
- Is the voltage greater than 10 volts?
Yes
GO to B5.
No
REPAIR the circuit. CLEAR the DTCs. REPEAT the self-test.
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B5 CHECK THE STOPLAMP SWITCH
- While pressing the brake pedal firmly and releasing it. Measure the resistance between the stoplamp switch pin 2, component side and the stoplamp switch pin 3, component side.
- Is the resistance less than 5 ohms with the brake pedal released and greater than 10,000 ohms with the brake pedal applied firmly?
Yes
GO to B6.
No
INSTALL a new stoplamp switch. CLEAR the DTCs. REPEAT the self-test.
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B6 CHECK THE ABS MODULE FOR A SHORT TO VOLTAGE
- Ignition OFF.
- Disconnect: ABS Module C135.
- Ignition ON.
- 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. REPEAT the self-test.
No
GO to B7.
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B7 CHECK CIRCUIT CES09 (VT/OG) FOR AN OPEN
- Ignition OFF.
- Measure the resistance between the stoplamp switch C278-3, circuit CES09 (VT/OG), harness side and the PCM C175b-47, circuit CES09 (VT/OG), harness side.
- Is the resistance less than 5 ohms?
Yes
GO to B8.
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 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 Information. 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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