Pinpoint Test A: The Speed Control Is Inoperative

WARNING: This page is about a different car, the 2006 Mercury Montego, 2006 Ford Freestyle, and 2006 Ford Five Hundred. However, it is still accessible from the selected car via links, so may be relevant.

A1 CHECK FOR DTCs
- Review the recorded DTCs from the PCM self-test.
- Are any DTCs recorded?
Yes: REFER to the POWERTRAIN CONTROL MODULE (PCM) DIAGNOSTIC TROUBLE CODE (DTC) INDEX table.

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 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 C175b-19, Circuit 848 (DG/OG), Harness Side & PCM C175b-30, Circuit 151 (LB/BK) & Harness Side

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 scan 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 to continue diagnosis of the digital TR sensor.
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 scan 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 scan tool: PCM Vehicle Speed PID.
- Monitor and record the PCM vehicle speed PID while driving the vehicle at 48 km/h (30 mph) as indicated on the speedometer.
- 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 (OSS) sensor 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 INSTALLATION . 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.