You really need to measure it at the input to the PCM from everything I've read. And it makes sense to do that to compensate for the voltage drop in the wire between point A and B. What I don't understand is why we don't read it at the ECM on the block which controls engine function. Maybe someday I'll figure that part out. Or maybe it is just a convenient place to read it.
This is how I did it:
With the key on, engine off you need to probe the apps wire to see where your voltage is currently set at.
The best location to probe the wire is on the PCM (power control module) which is located off the passenger side of the firewall.
• You want the C1 connector, this is the connector closest to the engine,
• You want the orange wire with the dark blue tracer which is pin # 23
• Voltage should read somewhere around 0.5 volts,
• At this point the voltage reading does not matter, it just has to be accurately written down for later reference.
*** TURN THE IGNITION OFF ON THE TRUCK ***
Resetting the APPS Sensor cont. page 2
(Accelerator Pedal Position Sensor)
2nd generation 24 valve trucks only.
• The apps sensor is located slightly above and a little to the left of the injection pump.
• Remove the black plastic cover that is located by your injection pump.
The two screws that are holding it are plastic, do not put any downward pressure on them or you will never get them off.
• Un do the 6 - 10 mm headed bolts that hold the bracketry in place.
(DO NOT REMOVE THE CABLES)
You will notice the apps is on the back of the bracketry that you just removed, it is held in place by 2 - 20 bit screws. These screws have a little bit of locktite on them so make sure you have a good socket and gently give a little tap with a hammer before attempting to loosen. Be very careful these screws strip very easily and you only get one shot at them.
• On the apps you will find a white tag that gives you the information on what the apps adjustment should be.
• After loosening the screws you can rotate the apps both clockwise and counter clockwise to get the adjustment you need.
• The reading you took at the beginning of the process on pin # 23 should match the white tag on your apps, if not adjust accordingly.
