How To Test The Camshaft Position Sensor (1997-1999 Ford 4.6L, 5.4L)

The cam sensor on your 4.6L or 5.4L Ford pick up (or SUV) is a variable reluctance type sensor that has two wires coming out of its connector.

In plain English, this means that this type of cam sensor can easily be tested with a multimeter in Volts AC mode.

You don't need a scan tool to test the Ford 4.6L, 5.4L camshaft position sensor (although a scan tool does come in handy to read the diagnostic trouble codes).

The aim of this tutorial is to walk you thru' the whole thing step by step.

Here are the contents of this article at a quick glance:

  1. Important Tips And Suggestions.
  2. Symptoms of BAD Ford Cam Sensor.
  3. How Does The Crank Sensor Work?
  4. TEST 1: Verifying The Cam Signal.
  5. Where To Buy The Cam Sensor And Save.
  6. More Ford 4.6L, 5.4L Tutorials.

En Español You can find this tutorial in Spanish here: Sensor de la Posición del Árbol de Levas (1997-1999 Ford 4.6L, 5.4L) (at: autotecnico-online.com).

Important Tips And Suggestions

TIP 1: The cam sensor is located on the timing chain cover. More specifically, it's located right near where the timing chain cover meets the left (driver side) valve cover. The second image in the image viewer points to its location.

TIP 2: If your vehicle doesn't start, then it's very important that your Ford's battery is fully charged for the cam sensor test. The battery must have enough reserve power to crank the engine easily for several seconds.

TIP 3: The cam sensor test described in this tutorial is done with the engine cranking/running. Take all necessary safety precautions, use common sense and think safety all of the time working around a cranking/running engine.

Symptoms Of A BAD Ford Cam Sensor

It's been my experience that a bad cam sensor usually doesn't cause a no start condition. Usually the vehicle runs but with the check engine light (CEL) anouncing a cam sensor trouble code... but not always.

In some cases a bad cam sensor will cause the engine to stall or not start at all. Here are some more specific symptoms:

  1. Trouble codes lighting the check engine light up:
    1. P0340: Camshaft Position Sensor Circuit Malfunction.
  2. Engine takes a long time to start.
  3. Engine stalls after starting.
  4. Rough idle.

In all cases, when the cam sensor fails... the PCM will light up the check engine light and store a cam sensor code to further confirm the problem.

How Does The Cam Sensor Work?

How To Test The Camshaft Position Sensor (1997-1999 Ford 4.6L, 5.4L)

The powertrain control module (PCM) uses the cam sensor signal to find out the camshaft's position and to determine when piston #1 is at top dead center (TDC) on its compression stroke.

The powertrain control module also uses the cam sensor to synchronize the firing of your Ford's fuel injectors.

If your 4.6L and 5.4L V8 with coil-on-plug (COP) ignition coils, the powertrain control module also uses the cam sensor to fire them in the correct firing order.

Here are some more specifics of the camshaft position sensor:

The 4.6L, 5.4L cam sensor is a two wire variable reluctance sensor. What this means is that:


  1. It doesn't need an external power source of ground source (like in a 3 wire type Hall Effect sensor).
  2. The cam sensor creates its own signal (AC Volt signal).
    1. The DK GRN (dark green) wire connects to powertrain control module (PCM) connector pin 85 and delivers the cam position signal info.
    2. The LT BLU (light blue) wire connects to the PCM's connector pin 91. This wire provides the cam sensor with ground.
  3. Once the engine starts to crank, the cam sensor produces an analog volt (AC) signal.
  4. The PCM, once it gets the cam sensor signal:
    1. The PCM fires the fuel injectors sequentially and in the correct firing order.
    2. If your pickup (or SUV) is COP ignition coil equipped, the PCM fires the ignition coils in the correct firing order.
  5. So, with both fuel and spark being fed to each engine cylinder, the engine in your Ford (or SUV) starts.

OK, let's get this show on the road and get started with the cam sensor test in the next page...