What is the Technical definition of CPS ?
Cam Position Sensor . Since a diesel engine does not have a true ignition system, the Cam Position Sensor reads the revolutions of the Camshaft and signals to the ECM that the engine is truly running and to keep the fuel flow going. When the CPS goes bad, the computer does not receive a signal from the CPS and shuts the truck down. The symptoms can be intermittant and give some time to replace or immediate and the truck is dead right now.
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Failure Symptoms :
One sign of a failed Cam Position Sensor is that your Tach will not move on an extended cranking of the engine Short cranking, on a good CPS will not register either. If you have an Auxiliary Powertrain Control Module (APCM) on your vehicle, it may not register RPM's either. The Tach receives its signal from the Cam Position Sensor. Without the CPS signal the tach won't work.
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Before Replacing your CPS make these checks-
Is fuel getting to the fuel bowl? Is fuel filer clean?
Do you have recommended oil level in engine? Low oil will affect high pressure oil pump and fuel delivery.
Do you have a chip on the truck? If so disconnect battery, remove chip and clean connections and reconnect.
Check the cranking voltage of your Batteries. If low, the battery can still turn the engine over but does not have enough power to fire the injection control module or keep the glow plugs hot.
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In 2002 and later 7.3L Diesels, Ford changed how the TACH gets its signal from the computer controller so the "No TACH Movement during Extended Cranking" indicator will probably not work for you. However, if the truck was running and you notice the Tach fall to zero, suspect the CPS.


To install the new CPS:
you will need a 10mm wrench or a 10mm socket on a 3" extension, a flathead screw-driver and a replacement CPS will do the trick.

Locate the CPS.
Under the passenger side of the truck. It is located on the engine block at about 10 o'clock behind the front crankshaft pulley. Uunplug the wiring harness, loosen and remove the 10mm bolt, and gently pry the old CPS out with the flat screwdriver.

Note:
If your vehicle has the ambulance package you may find an alternator in the way while looking for the CPS. The Ambulance Package has dual alternators. The CPS may not be as easy to see and harder to get too, but it’s still in the same place.

Installation:
The opposite of removal. After installation, start the vehicle and you should have a operating engine!
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