Dead pedal

Trapper

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Joined
Aug 5, 2006
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2,878
Any ever get a dead pedal at low speed off roading there 24v. It happen to me a few times today. Got home ok. Checked the plugs to the APPS and the VP pump. Everything checked out ok even went to the auto parts store for them to pull any codes. I know the check engine light came on a few times and stayed on. But when I got home it was ok. I even swapped out the fuel system relay in the fuel box. I will be checking my engine harness carefully this week. Any other suggestions. I have plenty of fuel from my Glacier pump. 12 to 18 psi.
 
FWIW first thing easiest thing disconnect both negative terminals on batts. Turn key leave key on walk away for 15-20 minutes. Turn key off reconnect negative terminals and see what happens. These vp.trucks are throttle by wire if you will and this process should reset those electrical gremlins. This does not always work your APPS can be out of adjustment voltage wise as far to operate correctly.
 
You can adjust it slightly to get it back to spec range. The set voltage on every apps has a sticker on it with numbers being factory voltage its gotta be close you can probably look up apps adjustment procedure on here and find it all.
 
I've been retreading the vp diagnoses info from BlueChip also. I hope it's something simple. I might just p pump it if the vp goes south. I need reliability in the desert.
 
An easy thing to do would be to find a buddy with the same truck and swap APPS. See if the problem follows the APPS to his/her truck or stays with yours. If it stay with yours, probably the ECM. That can be swapped to if you find a truck very similar to yours. It is most likely one of the two. If it is the VP, you'll get codes "most" of the time. ECM's on drugs have been knows to be jerks and not throw codes when they go bezerk. I chased a gremlin in my '02 for months.
 
My 01 had intermittent dead pedal when I first bought it a few years ago. No codes were present. Adjusted the APPS to spec and it never happened again. Adjust it to spec. Do a recal and see what happens. Potentiometers can develop a dead spot. Typically they develop where the contact rides most of the time (constant pedal at highway speed). If that happens then adjusting it will not cure the problem.

Just as Jory said the VP dying TYPICALLY will throw a code P0216 or numerous others.
 
Typically they develop where the contact rides most of the time (constant pedal at highway speed).

Exackary where mine crapped out. Same thing goes for the fuel tank sensor. Don't always fill up to 1/4 tank every time. Fill all the way up and use it all the way down. It will make it last longer. [/side note but same principle]
 
Exackary where mine crapped out. Same thing goes for the fuel tank sensor. Don't always fill up to 1/4 tank every time. Fill all the way up and use it all the way down. It will make it last longer. [/side note but same principle]

I hope that's what mine is doing. It did it a few times this morning but got me to work.
 
If you have any kind of display where you can watch your APPS %, get out in the middle of nowhere. Start off and ramp it up as slow as you can. Note the % where is craps out. If you keep pushing it down, it should clear back up. Do this several times. If you have consistent trouble from say 13-17% every time, then your APPS is probably fish food.
 
I'm going to hook up a volt meter when I get home. I was tired yesterday.
 
I logged mine when I got a used one from a guy here. I slammed the pedal up and down and up and down then went up and down real slow. It should be smooth.

APPSLog.jpg


Some reading:

http://www.competitiondiesel.com/forums/showthread.php?t=130278&highlight=test+apps

http://www.competitiondiesel.com/forums/showthread.php?t=23376&highlight=test+apps

I also made a harness with pig tails that connects to an APPS to bench test it. I powered it with a DC power supply and used a DMM. I can't seem to find a picture or schematic of it. I can probably find it tonight if you need a pin-out for it.
 
And there is this if you haven't already found or seen it:

RESETTING THE APPS SENSOR.
(ACCELERATOR PEDAL POSITION SENSOR)
2ND GENERATION 24 VALVE TRUCKS ONLY.

LIST OF TOOLS NEEDED

DIGITAL VOLT METER
# 20 TORQUE BIT SOCKET
# 1 PHILLIPS
# 10 MM SOCKET

Proper service and repair procedures are vital to ensure personal safety of those performing the repairs. Standard safety procedures and precautions should be followed at all times to eliminate the personal injury or improper service, which could damage the vehicle or compromise its safety.
Although this material has been prepared with the intent to provide reliable information, no liability is assumed in reliance of this material.

It has come to my attention that a lot of people think by disconnecting & re-connecting the batteries and stepping on the throttle it is going to reset the apps, no, that is not correct. It is impossible to adjust your apps if you do not know where it is supposed to be set at. That is why you need the voltmeter.

This is the procedure I use to re-set the apps.

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.
 
well jory...we aint all got a datalogger on our dd dontcha know....

can ya git me one tho?
 
i bet i can scrounge up a coon or 2

jus tell the op his vp is toast..we all know it is..we just hate to admit it
 
I chased gremlins until the APPS, ECM and VP were replaced. Just tryin' to save him some trouble. ;)
 
LOL The ol VP is dead game. I am pretty sure the "other forum" has ruined VP trucks for a lot of people. I honestly like a good running VP truck with mild mods but if you ever google any issues you would think a burnt out license plate light means the VP is dying....
 
Mine used to crap out between 40-43 mph and every time I used cruise control. So if it happened at the same peddle position when off roadin, I would point at the APPS
 
Good info there the info I put up solved my problem,glad others chimed in
 
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