Check engine light, goofy throttle, codes

[ARenaissanceishMAn]

Hey all, I have a 2001 24v and a few months ago i started noticing the throttle acting weird / revving up and letting off on its own a tiny bit when cruising around 55mph, I would then put it on cruise control and wouldn't notice it. Then the other day I noticed after driving on the highway/ with cruise control I'd get off to get fuel and the truck would be idling high around 1k until I shut it off and re start then it would be fine. Finally on the trip home I was running 70mph with cruise control on and the cruise control cut off and the throttle went unresponsive and threw a check engine light. I did the key thing to get the codes on the dash and got p0500,p1693,p0121,p0523,p0602. I'm running a Smarty and from my uneducated google knowledge I'm assuming I have a bad apps and if I replace it I should be good to go. My question for all of you is, is my assumption of  having a bad apps correct, is there anything else I should look into from those codes. Also if I do need a apps where should I buy it. My brother inlaw is a self employed mechanic and seems to get parts cheaper if thats a consideration, i'm pretty sure thats just threw people he has accounts with though such as orileys, napa places like that. All your help and knowledge would be appreciated. Thank you.

Edited April 22, 2017 by ARenaissanceishMAn

[deehammer]

Sounds like an APPS to me. Run through the P0121 code troubleshooting on the Article tab it should pin point the APPS. If u do replace it go with a Timbo. I think they are $165 or so. Easy to install and calibrate

[dripley]

 I would add that it would be good to clear the codes and see if any do come back. If you have nothing to check codes with it would be advisable to get one. The key trick is not always reliable to get your codes. 

 I too have been experiencing some surging over that past year and a half or so including a dead peddle on 2 or 3 occasions. I had APPS codes and the diagnostics told me it was bad. Now I already had a Timbo so was a little surprised but never the less bought a new one. It did not fix my problem. Mine never did occur while the cruise was set. Do you know what kind of APSS you have?

 Do you have fly by wire cruise or does it run off the vacuum system? The fly by wire bypasses the APPS, another reason I believed mine was a APPS issue. If you have a manual trans yours is probably fly by wire. The easiest way to tell is the throttle pedal will not move down after the cruise is set. Since yours did it thru the cruise maybe yours is not fly by wire.

 Thru working on this problem and any other time I had to disconnect the batteries to work on the truck I began noticing that it seemed any time I disconnected the batteries the surging would go away. Maybe for a week sometimes more it would be surge free. Not sure if this was really working I redid some of my electrical connections on a couple of occasions and sure enough this helped and I was surge free for 5 or six weeks. I had also noticed the tops of my batteries were pretty dirty and I took my volt meter and could read a fair amount of voltage across the tops. So I cleaned them up really good. I have now been surge free for over 2 months. 

 Now being as electrically challenged as I am, I am not sure what is happening. Kind of flying by the seat of my pants for now. I know disconnecting the batteries does not reset any computer as some say. I do know bad grounds a hot connections can cause funny issues with these trucks.