Pinpoint Test A: The Speed Control Is Inoperative
Speed Control
Pinpoint Test A: The Speed Control is Inoperative
Normal Operation
The PCM sends a signal through circuit 151 (LB/BK) to the speed control switch, which passes through the clockspring. The return signal is sent through circuit 848 (DG/OG) and the clockspring. When the brake pedal is applied, the ABS module sends a message to the PCM to deactivate the speed control if engaged.
The speed control deactivator switch interrupts circuit 1119 (RD) removing the voltage signal to the PCM when the brake pedal is firmly applied. This is a redundant signal to the PCM.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- PCM not configured for speed control
- Speed control switches
- Stoplamp switch
- Digital Transmission Range (TR) sensor
- Vehicle speed signal
- PCM
PINPOINT TEST A: THE SPEED CONTROL IS INOPERATIVE
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A1 VERIFY PCM CONFIGURATION
- Enter the following diagnostic mode on the scan tool: Programmable Parameters.
- Verify that the speed control is enabled in the PCM.
- Is the speed control enabled?
Yes
GO to A2.
No
ENABLE the speed control in the PCM using the scan tool programmable parameters menu. TEST the system for normal operation.
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A2 CHECK FOR DTCs
- Review the recorded PCM DTCs from the continuous and on-demand self-tests.
- Are any DTCs recorded?
Yes
REFER to DTC Charts. Diagnostic Trouble Code Tests and Associated Procedures
No
GO to A3.
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A3 CHECK THE VEHICLE SPEED
- Check for correct operation of the speedometer.
- Does the speedometer operate correctly?
Yes
GO to A4.
No
REFER to Instrument Panel, Gauges and Warning Indicators to continue diagnosis of the speedometer.
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A4 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 A5.
No
Go To Pinpoint Test B. Pinpoint Test B: DTC P1572 Or DTC P1703
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A5 CHECK THE SPEED CONTROL SWITCH
- Enter the following diagnostic mode on the scan tool: PCM DataLogger.
- Press each speed control switch button while monitoring the speed control switch PID (SCCS).
- Does the PID value agree with the switch position?
Yes
GO to A6.
No
If only one switch does not display the correct PID value, INSTALL a new speed control switch. REFER to Speed Control Switch Speed Control Switch. TEST the system for normal operation.
Otherwise, Go To Pinpoint Test C. Pinpoint Test C: The Speed Control Switches Do Not Operate Correctly
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A6 MONITOR THE TR PID
- Ignition ON.
- Enter the following diagnostic mode on the scan tool: PCM DataLogger.
- Monitor the PCM PID (TR).
- Select DRIVE.
- Does the PID value agree with the transmission range selector lever position?
Yes
GO to A7.
No
REFER to Transmission Control Systems. Testing and Inspection
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A7 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. If equipped with fire suppression system, GO to A8 . 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. If equipped with fire suppression system, GO to A8.
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A8 REPOWER THE FIRE SUPPRESSION SYSTEM
WARNING: If the vehicle is equipped with a fire suppression system, repower the system. For important safety warnings and procedures, refer to Fire Suppression System. Failure to follow these instructions may result in serious personal injury. Procedures
- Verify that the fire suppression system is repowered. Refer to Fire Suppression System. Procedures
- Is the fire suppression system repowered?
Yes
Fire suppression system repowering is complete.
No
REFER to Fire Suppression System. Procedures
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