StevenAg03

i have been having this problem with my truck ever since i got it last janurary, however as of lately, it is actually becoming a problem.

back when i first got the truck in Jan of 07, i noticed that after driving with the cruise control on for some time, idle would be up around 1000rpm and the exhaust brake wouldnt work. about 9 months ago i was driving from Houston to dallas. i took my exit in ennis and when i came to a stop at the light the idle was around 1100-1200. as soon as i let the clutch out, i got a CEL and had no throttle response. checked the codes with my superchips and had P0121. This is a voltage to low code. i cleared the code and when i started the truck back up, everything was good to go. havent had any problems for the last 9 months. then as i was driving to work monday morning, i lost all throttle and the CEL came on. this time i was driving with the cruise on and going 65ish. pulled over and repeated the process above. the difference this time is that it happened while i was driving down the highway.

this morning as i was "evacuating" houston i drove through college station to pick my fiance up. when i exited the highway and pushed in the clutch at the light, idle was ~1200 rpm. i took off through the light and shortly there after no throttle and p0121. cleared the codes and off i went. about 45 minutes later (near North Zulch), it happened again. the difference the last time it happened is that i hadnt been using the cruise for a good 20 minutes.

now with the code and some common sense, one would say that the APPS is the likely candidate. however, the only common theme between all situations is that the cruise had been in use.

to test my theory out, i drove from North Zulch to Enis (hour and a half) without cruise. no problems what so ever. when i stopped in enis idle was normal 800-900 rpm. i decided since i was somewhat close to home, i would try the cruise and see what the results were. i used it for all of about 20 miles. sure enough, as soon as i turned it off and came to a stop, idle was around 1100 rpm. i did not get a CEL and no throttle this time though.

i think the issue may be that the cruise is giving some feedback, even when turned off. it is sporatic though. sometimes, after using the cruise, idle will return to normal, but most of the time it wont.

can someone please help me out or give me places to check? i dont want to keep thinking it is a problem with the cruise and be stranded on my way back with a bad APPS.

PLEASE HELP....

Busboy

The cruise control won't give you "no throttle response". I'd be looking for a Timbo APPS replacement.

StevenAg03

not to discount your knowledge, but i dont understand why it works perfectly when not using the cruise and has problems when cruise is used...

SWC

I had the same problem after using the cruise the Pacbrake not engaging. I ended up bypassing the ecm to get the exhaust brake to engage. The engine idle speed was close to normal slightly higher. I lived with this for 4 years. The dead peddle symptoms did not occur very often until about 1 year ago. I did buy the Dodge APPS. Problem solved.
I would follow Busboy's advice on checking out the Timbo APPS. Dodge loves their APPS very dearly and charges accordingly. Timbo's APPS is very reasonably priced and will probably last longer. Timbo's APPS was not available when I replaced mine. There is a long thread on TDR discussing how the APPS works and Timbo and several others working together to find a reasonable solution.
Stan

Busboy

No problem The cruise control servo only repositions the throttle quadrant, the APPS decides what response or signal to send to the VP. Like SWC says the TIMBO APPS is well documented on here and will be MY next replacement. Good luck!

StevenAg03

i have been doing some more research and everything has led me to your conclusion.

i have been in contact with timbo and will soon be ordering one from him.

THANKS FOR THE REPLIES...

Flsnowman

I have the same problem with the exhaust bake not engaging. I have had the APPS replaced and the injector pump (that was under warranty, luckly). And I still have problems with the EB not engaging when the curise contorl is used. If I am not using CC the EB works fine. My last trip to the deal I was told "You are not suppose to use the EB with the CC on." The reasoning given to me was "the EB triggers the CC to disengage like the service brakes". I don't buy any of it, why is the RPMS at 1000? Dealer couldn't give me an answer, suggested that when I figured it out let them know so they could instruct thier tech. I think there APPS is poorly designed just like thier stock lift pump.

johnh

the strange thing is when my APPS went, the only time i could drive without the engine giong to idle was with the CC engaged

nickg

I'm going to have to dig deeper, cause as far as I can tell , either your foot or the cruise actuator physically moves the APPS (unlike a GM 6.5 which does not use the APPS when the CC is on), I cant see how if your throttle dont work how the CC can???????

SWC

nickg, I believe that the 2nd Gen 24 valve cruise control is electronic. I assume it is in the ECM.
I do not understand how activating the cruise control starts the problem with the ECM not reading a closed throttle from the APPS. That is the problem that I saw before I replaced my APPS. I delayed replacing my APPS until I started experiencing more frequent throttle dead pedal situations.
Stan

nickg

Stan
I have not had time to dig thru the manual...but my 01 has a vacuum operated cruise control actuator that has a cable that moves the APPS, I'm 99.99% sure that if you loose vacuum the cruise will not work, and if thats the case then the cruise does not bypass the APPS.
...but then again I've been wrong about things in the past

SWC

Nick, I am wondering if what you are referring to as the cruise control cable is a cable that is tied into the automatic transmission shifting.
When I replaced the APPS on my truck the repair manual referred to a second cable that attaches to the arm that the throttle cable attaches to. I believe this cable is used to shift the automatic tranny down when given full throttle.
I don't have the shop manual here beside me so I can't give you the right name for that cable.
Maybe someone who knows these 2nd gens better can give better advise.
flsnowman if you still following this thread I did bypass the ECM for activating my Pacbrake when the ECM would not read a closed throttle from the APPS. If you are interested I can give you more details.
Stan

jfpointer

The original poster would have completely electric cruise control in his '02 with 6 speed, at least according to my FSM. Not vacuum-controlled at all.

johnh

on mine if i have no vacuum i have no cruise

CapnRam

Over the last couple of weeks i have lost my CC, it will engage then as soon as a load is put on it, it kicks off, i dont have any dead pedal problems, nor the high idle, just the CC not working now, i have a 99, so is this a vaccum problem or is this electronic? Thanks for any info..

Capn