gwbrehm

I've had a APPS issue for several years now on my 2004 dodge 3500 and it only occurs when its cold outside. My truck begins surging but not gently, it feels like someone stomped on the accelerator and then luckily almost right away the APPS throws two codes and gives me a dead pedal. I coast to the side of the road clear the codes reset the pedal only to have it repeat this for about 10-15 minutes until the truck is warmed up. Once the engine warms up and I clear the codes it runs fine the rest of the day.

I have reset the APPS several times, cleaned the battery terminals, replaced the batteries, cleaned the chassis and motor ground connections with no luck. Since it only occurs during warm-up I began to suspect the intake heater grid so, I disconnected the power to the grid heater and the problem went away (so far). I have read that these trucks work fine without the heater in milder climates, but, I would like to get to the bottom of this and make a permanent fix without just throwing money at it. My best guess is that it is a ground issue either through the grid relay or the ECM but not sure. I'm hoping that someone here may have dealt with this in the past and could offer some guidance. Thanks in advance for any input

SuperGewl

What codes do you get? Follow the diagnostic trouble shooting for them to get to the bottem of it. You may need a new ECU.

gwbrehm

I get P2121 & P2123, but, only when its cold. All summer long it works perfect and once the truck warms up and I clear the codes it works fine. I've reset the voltage on the APPS, but, since it works fine the rest of the time I have ruled it out as the problem. I was considering the ECM, I run the truck stock and it has 102,000 miles. Thanks

Grit Dog

Not sure the grid heater should affect the APPS unless it's in the ECM like you suggested.
My buddies '03 APPS went out, and it was giving him trouble (and codes) for sometime before the truck was constantly a dead pedal. When that happened, I reset the voltage, it would work fine for a few stomps on the throttle then dead/codes again. I'm sure it's a safety feature that kill the throttle to prevent it from taking off on you.
If memorey serves, he was getting 2121 and 2122 codes, but they're all related to APPS failure.
I'd be comfortable in spending the $ to replace the APPS. You can get them significantly cheaper than the dealer at a Cummins shop and not a difficult repair.

gwbrehm

I thought the same thing about the APPS, but, what doesn't make sense to me is that it works perfect in warm weather and now that the grid heater is disconnected I'm not having any more problems. I don't think its the grid heater either, but, it appears that the voltage draw from the heater is somehow causing excess voltage to effect the APPS. If it was a year round issue it sure would be a lot easier to diagnose, it's got me stumped.

gwbrehm

My problem came back with the grid heater disconnected so I broke down and picked a replacement APPS from Timbo. Honestly I didn't think it would fix my problem, but, to my surprise everything appears to be working normally.

Blown Away

I'm having the same problem. My truck is a 2004 600ho with smarty jr. I had it set to the 2nd setting which I belive is tow. The truck runs great in the summer, no problems and plenty of power. When winter rolls around with the colder temps I noticed that during warm-up the high Idle works fine the first time then it starts hunting and occasionally revs to about 1/2 throttle by itself. I've been driving down the road and get a dead throttle then all of the sudden it takes off and I havr to stomp on the binders. I finally decided itds too dangerous to run like that so I went back to the stock setting using the smatyty jr, now it sems to be fine, but I really need the power back. Any recomendations? What is the APPS? Can it be re-set or does it need to e reoplaced?

Thanks

gwbrehm

That was my problem exactly, kind of scary when it decides to take off by itself in traffic. Mine continually got worse and more dangerous. I started out by resetting the voltage on my APPS (Accelerator Pedal Position Sensor) and it worked for a while but eventually it didn't make any difference. If you do a search on this forum for resetting the APPS you will find a step by step procedure to reset the voltage. This only works for the early 04's with the APPS under the hood. Late 04's have the APPS inside the cab behind the accelerator pedal. Over the last several years I have tried everything I could think of to correct the problem on my truck. I run my truck stock so I'm not familiar with how the smarty affects the APPS. Replacing the APPS is what finally corrected my problem and my advise would be to replace it. There is a guy on these forums named TIMBO that markets his version of the APPS, he sells his for around $160 which is a lot cheaper than the $485 price tag from the dealer. Here's his web site:

http://www.dodgecumminsapps.com/index.html

Good Luck