Pinpoint Test A: The Speed Control Is Inoperative: Testing

A1 CHECK FOR DTCs
- Review the recorded DTCs from the powertrain control module (PCM) self-test.
- Are any DTCs recorded?
- Yes : REFER to the POWERTRAIN CONTROL MODULE DIAGNOSTIC TROUBLE CODE INDEX .
- No : GO to A2.

A2 CHECK THE SPEED CONTROL SWITCH

Disconnect: PCM C175b.

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

SPEED CONTROL SWITCH RESISTANCE REFERENCE

Speed Control Switch	Resistance Value
OFF	Less than 5 ohms
CANCEL	110 - 130 ohms
SET-	276 - 324 ohms
SET+	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 . CLEAR the DTCs. REPEAT the self-test.

A3 MONITOR THE TRANSMISSION RANGE PID
- Connect: PCM C175b.
- Key in ON position.
- Enter the following diagnostic mode on the diagnostic tool: PID Data Monitor and Record.
- Monitor the transmission range 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 - CVT or AUTOMATIC TRANSAXLE - 6 SPEED .
A4 CHECK THE PARKING BRAKE WARNING INDICATOR
- Key in ON position.
- While observing the parking brake warning indicator, apply and release the parking brake.
- Does the parking brake warning indicator operate correctly?
- Yes : GO to A5.
- No : REFER to INSTRUMENT CLUSTER to diagnose the parking brake warning indicator.
A5 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 A6.
- No : REFER to the INTRODUCTION - GASOLINE article to diagnose the output shaft sensor (OSS) signal.
A6 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 . 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. CLEAR the DTCs. REPEAT the self-test.