Pinpoint Test A: The Speed Control Is Inoperative

A1 RETRIEVE THE RECORDED POWERTRAIN CONTROL MODULE (PCM) DTCs FROM BOTH THE CONTINUOUS AND ON-DEMAND SELF-TESTS
- Check for recorded PCM DTCs from the continuous and on-demand self-tests.
- Are any DTCs recorded?
- Yes : REFER to the POWERTRAIN CONTROL MODULE (PCM) DIAGNOSTIC TROUBLE CODE (DTC) INDEX to continue diagnosis.
- No : GO to A2.

A2 CHECK THE SPEED CONTROL SWITCH

Key in OFF position.
Disconnect: PCM C175b.

Measure the resistance between the PCM C175b-19, circuit 151 (LB/BK), harness side and the PCM C175b-30, circuit 848 (DG/OG), harness side while pressing the speed control buttons as follows:

SPEED CONTROL SWITCH AND RESISTANCE VALUE

Speed Control Switch	Resistance Value
OFF	Less than 5 ohms
COAST	276 - 324 ohms
SET/ACCEL	552 - 648 ohms
RESUME	1,021 - 1,199 ohms
ON	1,941 - 2,278 ohms
No switch pressed	3,965 - 4,655 ohms

Fig 1: Measuring Resistance Between PCM Connector Terminals

Courtesy of FORD MOTOR CO.

Are the speed control switch resistance values OK?

Yes : GO to A3.
No : INSTALL a new speed control switch. REFER to SPEED CONTROL SWITCH . TEST the system for normal operation.

A3 CHECK THE DIGITAL TRANSMISSION RANGE (TR) SENSOR
- Connect: PCM C175b.
- Apply the parking brake.
- Key in ON position.
- Enter the following diagnostic mode on the diagnostic tool: PCM Digital Transmission Range (TR) Sensor PID.
- Monitor the digital TR sensor PID.
- Select DRIVE.
- Does the PID value agree with the transmission range selector lever position?
- Yes : GO to A4.
- No : REFER to AUTOMATIC TRANSAXLE/TRANSMISSION - 4R70W/4R75W or AUTOMATIC TRANSAXLE/TRANSMISSION - TORQSHIFT to continue diagnosis of the digital TR sensor.
A4 CHECK THE DIGITAL TR SENSOR FOR CORRECT ALIGNMENT
- Check the digital TR sensor alignment. Refer to AUTOMATIC TRANSAXLE/TRANSMISSION - 4R70W/4R75W or AUTOMATIC TRANSAXLE/TRANSMISSION - TORQSHIFT .
- Is the digital TR sensor aligned correctly?
- Yes : GO to A5.
- No : ADJUST the digital TR sensor. REFER to AUTOMATIC TRANSAXLE/TRANSMISSION - 4R70W/4R75W or AUTOMATIC TRANSAXLE/TRANSMISSION - TORQSHIFT . TEST the system for normal operation.
A5 CHECK THE BRAKE WARNING INDICATOR
- Key in ON position.
- While observing the brake warning indicator, apply and release the parking brake.
- Does the brake warning indicator operate correctly?
- Yes : GO to A6.
- No : REFER to INSTRUMENT CLUSTER to continue diagnosis of the brake warning indicator.
A6 CHECK THE VEHICLE SPEED
NOTE: This step may require an assistant.
- Enter the following diagnostic mode on the diagnostic tool: Anti-lock Brake System (ABS) Wheel Speed PID.
- Monitor and record the ABS module wheel speed PID while driving the vehicle at 48 km/h (30 mph) as indicated on the speedometer.
- Enter the following diagnostic mode on the diagnostic tool: PCM Vehicle Speed PID.
- Monitor and record the PCM vehicle speed PID while driving the vehicle at 48 km/h (30 mph).
- Does the speed indicated by the ABS module wheel speed PID match the PCM vehicle speed PID?
- Yes : GO to A7.
- No : See INTRODUCTION - GASOLINE and/or INTRODUCTION -- 6.0L DIESEL articles to diagnose the output shaft sensor (OSS) signal.
A7 CHECK FOR CORRECT PCM OPERATION
- Disconnect all the PCM connectors.
- Check for:
  - corrosion
  - 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. REFER to ELECTRONIC ENGINE CONTROLS - GASOLINE ENGINES . CLEAR the DTCs. REPEAT the self-test.
- No : The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.