Engine/Transmission (1998.5 - 2002) how to test APPS to verify if good or bad

[JamesSimpson]

Like the title says Is there any way to do this. Im thinking it may be bad ontop of the possible vp44. I would rather look at the small parts first then drop 1500 or so on the vp44

 

[Gary - K7GLD]

I've taken all the external measurements possible with a digital and analog multimeter, and have never found any significant differences in readings that would seem to identify a bad one, or the cause for it's specific failure. Largest single reason for APPS failures would seem to be the loss of proper operation of the internal rotating "wipers" on the rheostat portion.



This usually shows itself with erratic throttle application as speed is increased, or a "dead spot" at one or more specific points when the throttle is applied - usually at cruising speeds, since that is where the APPS inner contacts spend most of their time and most wear occurs.



At this point, substitution with a new, or known good APPS seems to be the only reliable test.



Here's a pointer to my past thread on the inner workings of an APPS, with instructions on a possible way to clean up internal contacts to restore proper operation - but I gotta tell you, these APPS units are cheap junk, with lots of potential failure points!



http://turbodieselregister.com/forums/showthread.php?t=99611

 

[JamesSimpson]

Could a failed APPS give you a false 216 code?

 

[Jeff Knight]

I had the 0216 code when I got the dead pedal. The dealer replaced the lift pump and the APPS. They said a bad APPS can cause the codes I had. The truck has been fine since. Time will tell. Jeff

 

[rivercat]

I gotta tell you, these APPS units are cheap junk, with lots of potential failure points!

Well said GARY, Ya know Its one thing to have a cheap part on the truck that needs more frequent changing then most light bulbs, but is another thing when its $350+ to change ! !

Let me add that they are never in stock anywhere local so you have to drive the bucking truck for 2-3days while you wait for it