Pinpoint Test F: The Speed Control Does Not Disengage When The Clutch Is Applied Diesel Vehicles

WARNING: This page is about a different car, the 2006 Ford Pickup, 2006 Ford F550 Super Duty, 2006 Ford F450 Super Duty, and 2006 Ford Cab & Chassis. However, it is still accessible from the selected car via links, so may be relevant.

F1 CHECK THE CPP SWITCH OUTPUT
- Disconnect: PCM C1381a.
- Measure the voltage between the PCM C1318a-36, circuit 306 (TN/LB), harness side and ground.
  
  Fig 1: Checking CPP Switch Output
  Courtesy of FORD MOTOR CO.
- Is the voltage greater than 10 volts with the clutch pedal released, and less than 1 volt with the clutch pedal pressed?
Yes : Go to F3.

No : Go to F2.
F2 CHECK CIRCUIT 306 (TN/LB) FOR A SHORT TO VOLTAGE
- Disconnect: CPP Switch C257.
- Measure the voltage between the PCM C1318a-36, circuit 306 (TN/LB), harness side and ground.
  
  Fig 2: Checking Circuit 306 (TN/LB) For Short To Voltage
  Courtesy of FORD MOTOR CO.
- Is any voltage present?
Yes : REPAIR the circuit. TEST the system for normal operation.

No : INSTALL a new CPP switch. TEST the system for normal operation.
F3 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 .

No : The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.