Erratic throttle with p2121

Hey guys,

My 07 has been acting up for awhile now and its progresively getting worse. Now the only code that pulls up is P2121 which is the app/tps. I stopped at the dealer and it's only 120 bucks for the whole peddle assembly and I've could have swarn that I've seen them a lot more then that so my only question is, is that the only thing that would be the cause of the code? Or do I need to be ordering something else?

Thanks for your help,
Austin

Ive had the same code popping up for awhile now, I've put in 3 peddle assemblies and no change. Its very frusterating and never know when it will do it. Sometimes its 2-3 times a day and then it will b fine for hundreds of miles. Sorry I was no help just looking for some answers as well.

When you replace it there is a process that you must go thru to teach the ECM that a new device has been changed. I am at work and can't remember what it is, but the service manual will explain it. It is something like turn key, don't start, depress the go pedal 3 times to the floor and turn ignition off.

sixspeed said:

When you replace it there is a process that you must go thru to teach the ECM that a new device has been changed. I am at work and can't remember what it is, but the service manual will explain it. It is something like turn key, don't start, depress the go pedal 3 times to the floor and turn ignition off.

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I have heard of doing this, but I wasn't completely sure on what it was. I got my new peddle assembly but haven't installed it yet. I'll mess with it later on today.

If anyone else can chime in with the procedure that would be great.

Thanks,
Austin

guys look up my posts...

trust me it is a ***** to do this thing, turned out mine was a wire that had made ground... ive been there and done this before.. just clicky on me and search.. i promise it will be worth your while..

p2121 apps comm error.. know it well...
p2122 know it as well..

I think I may have gotten lucky. Went to dinner last night and my check engine went off so I went ahead and pulled the battery cables off and swapped it out and haven had any trouble with it yet.

So hopefully since the light was of it reset it's self and I won't have to deal with the sequence that you have to go through to reset it. But I'll keep you guys updated.

But I will say this the truck really feels like it shifts a lot better so far which i don't know if that sensor could change that or not.

Ok, I hammered down one day coming to work and the check engine light came back on again and the throttle starting acting up again...

Does anyone know the sequence your supposed to go through to reset the tps/apps sensor?

Thanks,
Austin

To reset IIRC, Key on, press pedal slowly to floor and depress slowly, key off.
Crank up and drive.

Subd

guys believe me on this


THE DISCLAMER IS.. i have a very well documented thread on DTR about these issues with these PITA codes... Below is a small summary of what to check and how my mechanic and I solved the issues with these codes.. THIS iS NOT A COMMON PROBLEM ON COMP D, so forgive me for bringing another site into the picture.. BUT FWIW this aint cummins forum either.. so heres some honest to god advise now that i have time...

start with the basics on this.. first of all, make sure that your battery cables are clean and can be and tightened the way that they should be, also make sure that your batteries are completely charged and in good standings...

nextly check all of your grounds and make sure that you have nothing exposed. there is a super problematic wire that is right by the AC compressor on the right hand side that tends to rub through and cause hellashious problems electrically,

I do believe that wire is orange in color, (at least it is on my 05) I found that problem, and taped that wire up, and used wireloom on my truck and my fathers and have not had wiring problems since. I cleaned the PCM connections and made sure that the connections from the harness to the PCM were tight.. ...

I wound up cleaning those out with compressed air in a can and also wound up double and triple checking all of the connections up by the firewall... Those things on a bad road can come loose and really cause some problems.... As a matter of fact, one of those prongs was not making a full contact on the connection to the ECM and was causing some problems..

the connections to the ecm could be air blown, checked for connectivity, and bend the small prongs with GREAT delicacy and some really tiny needlenose pliers, and reconnected to ensure a proper connection, and zip tied for good measure... we did this with the batteries unplugged for well over an hour...

A TPS reset was never the problem, with bad connections it just wont work no matter what you chose to do, cant overcome a bad wire right? I went through three TPS's which IIRC are on national back order, and not one solved the problem...

Also from recent experience.. one domino effect can have a code on another, SOOOO if you have a FC code, P0483 or P0480, guess what, it might be screwing with your ecm and cause those erratic issues as well.. how do i know? been there and done that, RECENTLY too as you can see in my other recent thread...

finally if you have done all of the above, and you have a means to clear DTCs.. clear them out, that will always remove the doubt in your mind as to if it was done right or not...

hope this helps...

I found this on another forum...

When I get back from vacation I'm going to go ahead and try this and see what happens.

Here ya go

APPS Reset Procedure
This procedure has shown to help 24 valve ISB engines. It is basically teaching the fly by wire accelerator on these trucks to reread the position of the pedal and it's limits. Most complaints this will help with is poor acceleration, improper shifting, bucking in 5 and 6 speeds. Has been known to increase fuel mileage in some instances.

1. Set parking brake
2. Disconnect negative battery cables on both batteries
3. Turn ignition key to run(to drain any remaining capacitors)
4. Let truck sit for 30 minutes( this is the recommended minimum)
5. Return ignition to OFF position
6. Reconnect both batteries and secure, not a timed event
7. Turn key to run position(not start) and depress accelerator pedal slowly all the way to the floor
8. Allow pedal to return to top position slowly
9. Turn ignition switch OFF
10.Release parking brake

buddy..

try the reset out, but with all due respect, i HOPE it solves your problem, but what you seem to have did not solve (in my experience) with the above procedure...

TxDiesel007 said:

buddy..

try the reset out, but with all due respect, i HOPE it solves your problem, but what you seem to have did not solve (in my experience) with the above procedure...

Click to expand...

I am going to start looking for bad wires, I think your right with a bad wire somewhere because mine is starting to get worse and worse with that code and its starting to pop up a few more codes like throttle valve stuck open and I had another one but cant remember what it was.

I will check right around the ac compressor and see if I can find a problem.

Where are some of the problematic grounds located at also?

Thanks,
Austin

any and all grounds

should be checked, cleaned and wireloomed just to avoid these problems in general. Start with the very basics.. and also make sure your batteries are in tip top shape.. re read what i posted above... and take your time.. would not hurt to check your connections at the transmission either... and also please bear with me on this..

IF you have a P0483, DO NOT rule out the fan clutch... that damn thing causes more problems with our trucks than what it is worth.. remember one code can domino on another..

FWIW a buddy of mine was having similar issues with his... and it was also connections at the ECM.. not a good contact... his was an 04.5 tho... compressed air, a good clean up, zip ties, and voila...

sounds stupid but it has worked for two trucks..

Well I'm going to bump this up and say that I know what wire is causing it but just have to trace it down.

For anyone wanting to know if you just have the code P2121 it is:

12. (K167) APPS 1 RETURN CIRCUIT SHORTED TO OTHER CIRCUITS- and is a brown w/yellow stripe wire. Its right in the middle of the ecm plug. But I have traced it for about 30 mins and couldn't find any bad spots yet because it goes everywhere.