Pinpoint Test A: the Speed Control Is Inoperative
Speed Control
Pinpoint Tests
Pinpoint Test A: The Speed Control Is Inoperative
Refer to Wiring Diagram Set 31, Speed Control for schematic and connector information. Diagrams By Number
Normal Operation
The PCM sends a signal through circuit 151 (LB/BK) to the speed control switches, which passes through the clockspring. The return signal is sent through circuit 848 (DG/OG) and the clockspring.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- PCM not configured for speed control
- Speed control switches
- Stoplamp signal concern
- 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
- Check for recorded PCM DTCs from the continuous and Key ON Engine OFF (KOEO) 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 STOPLAMP SWITCH INPUT TO THE PCM
- Enter the following diagnostic mode on the scan tool: PCM DataLogger.
- Monitor the PCM PID BOO while applying and releasing the brake pedal.
- Do the PIDs agree with the stoplamp switch position?
Yes
GO to A4.
No
REFER to Antilock Brakes / Traction Control Systems continue diagnosis of the ABS system. Testing and Inspection
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A4 CHECK THE VEHICLE SPEED
- Check for correct operation of the speedometer.
- Does the speedometer operate correctly?
Yes
GO to A5.
No
REFER to Instrument Panel, Gauges and Warning Indicators to continue diagnosis of the speedometer.
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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
- 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 to continue diagnosis of the digital TR sensor. Testing and Inspection
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A7 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 A8.
No
Go To Pinpoint Test b. Pinpoint Test B: DTC P1703 or DTC P1572
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A8 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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