Hello everyone,

 

New to the forum here, have a 2000 Dodge 24 valve. I’m a mechanic by trade, bought the the truck off one of our customers. He had this issue towards the end of his ownership, truck would surge during idle and the odd time would throw APPS code but he could still drive it. 
 

The trucks had a couple different APPS sensors, OEM and aftermarket. When I bought the truck last summer I did a ton of upgrades/maintenance, starter, alternator, 2 new batteries, FASS and sump, fuel pressure gauge and a bunch of other things non related to the problem. I did all the APPS testing between sensor and ECM and everything checked out. 
 

After doing the timbo APPS my issues seemed to go away (the alternator change was around this time too). We have a truck bed camper and went on a couple long trips with no issues. I don’t drive it much in the winter but again when I did, no issues. The start of this year also had no issues, and then things slowly started to creep back. I’d be sitting at a stop light and truck would kick up a bit, started becoming more frequent, and now it’s dead pedalling again, I’ll take off for work in the morning, I’ll be trying to come to a stop and RPMS will stay high, then 2 minutes later CEL comes on and no throttle. Takes me a while to get into the system with my scanner, I’ll clear it and I can drive but will either rev real high right away and trip the light or it’ll throw it a minute down the road again. But then if I work through it enough times, and the truck warms up enough I can get going with no issues. I can go somewhere, shut the truck off, go in somewhere and drive all the way home, again no issues. But if the trucks cold or sitting for days it’ll give me issues.

 

I checked for AC noise and am getting 0.127V, is this possibly an alternator gone bad? Like I said I replaced it last year with the timbo and was good for awhile but now a year later dealing with the same problems. Just want to make sure I’m not missing something here. Seems weird to me that it goes away when the truck warms up. Any insight would be greatly appreciated! 

Well, that's a bummer!  Any codes?

 

You could hook up a scanner and monitor the throttle position on the display.  Drive the truck and when the symptoms occur at idle, see if the per cent of throttle changes on the display, or if it remains steady as it should. 

 

I think that you may still be getting an electrical interference of some kind.  I don't know much about the ECM operation, but I think the ECM has the capability to monitor and weed out false signals.  However, if too many false signals are being sensed in a specific amount of time, the ECM may consider the signals to be valid.  The APPS provides one of those signals.  It may be worth a try to leave the ignition switch in the "Run" position and slowly depress the throttle to the floor one time and release.  Turn the ignition switch off and then start the engine.  This is not a fix, but if there is electrical interference with the APPS, then the symptoms may disappear for awhile.  This may help to diagnose what is really going on.

 

- John

On 8/24/2024 at 9:46 PM, Tractorman said:

Well, that's a bummer!  Any codes?

 

You could hook up a scanner and monitor the throttle position on the display.  Drive the truck and when the symptoms occur at idle, see if the per cent of throttle changes on the display, or if it remains steady as it should. 

 

I think that you may still be getting an electrical interference of some kind.  I don't know much about the ECM operation, but I think the ECM has the capability to monitor and weed out false signals.  However, if too many false signals are being sensed in a specific amount of time, the ECM may consider the signals to be valid.  The APPS provides one of those signals.  It may be worth a try to leave the ignition switch in the "Run" position and slowly depress the throttle to the floor one time and release.  Turn the ignition switch off and then start the engine.  This is not a fix, but if there is electrical interference with the APPS, then the symptoms may disappear for awhile.  This may help to diagnose what is really going on.

 

- John

Hey John,

 

Thanks for the reply, was away for a bit and then was driving my TDI Jetta, have been driving the truck, the pedal reset seemed to work for a couple days. Then it started acting up again, now that it’s happening on almost every single drive I’m going to check the throttle position on the scanner while it’s doing it. But it seems to be getting worse. 
 

It’ll be revving high when I’m trying to come to a stop, doing it at idle or even while cruising it’ll surge up and then come back down. Saturday I fired the truck up and it went straight to 2k RPMs, shut it off and turned it back on and it was fine, kicked up a bit leaving but like before once up to temp it’s USUALLY okay, it has done it the odd time once warm but it’s rare. 
 

It’ll throw a code still but won’t dead pedal, it throws a P0222 Idle validation signal code. A weird thing I noticed if I plug my mini scanner in it takes forever to get all the monitors to run, but the CEL just disappears when you plug it into the OBD. No issues with snap on scanner. 
 

Is it possible I have an injector issue or oil issue causing it to idle up like it has been? 

2 hours ago, DunnerCummins24 said:

It’ll throw a code still but won’t dead pedal, it throws a P0222 Idle validation signal code.

 

P0222 (M) Idle Validation Signals Both Low Problem detected with idle validation circuits within APPS.

 

I would definitely find out why you are getting this code.  If the ECM does not get a signal for idle validation, then the engine rpms will not go to idle.  Which APPS are you using now - OEM or TImbo?  Either way, you could try adjusting the mechanical stop where the APPS is located in the engine compartment.  Back it off an extra distance to ensure the throttle will activate the idle validation switch that is built into the APPS.

 

2 hours ago, DunnerCummins24 said:

Is it possible I have an injector issue or oil issue causing it to idle up like it has been?

 

I seriously doubt that.  An injector misfiring would likely cause a miss or a timing knock.  Engine oil feeding a cylinder wouldn't allow the engine to shut off immediately when you switched off the ignition.

 

I think the P0222 in telling you something.  Double check all of the pin conditions in the connector to the APPS. 

 

- John

22 hours ago, Tractorman said:

 

P0222 (M) Idle Validation Signals Both Low Problem detected with idle validation circuits within APPS.

 

I would definitely find out why you are getting this code.  If the ECM does not get a signal for idle validation, then the engine rpms will not go to idle.  Which APPS are you using now - OEM or TImbo?  Either way, you could try adjusting the mechanical stop where the APPS is located in the engine compartment.  Back it off an extra distance to ensure the throttle will activate the idle validation switch that is built into the APPS.

Thanks for the info John! 
 

I have the timbo APPS, do you think it would be worth back probing the green wire and adjusting the set screw? I know the previous owner had an issue with the set screw backing itself out but this is an entirely different assembly than what he had when that happened. 
 

On 9/16/2024 at 5:30 PM, DunnerCummins24 said:

Then it started acting up again, now that it’s happening on almost every single drive I’m going to check the throttle position on the scanner while it’s doing it

 

I would do this step, first.  It would be good to know whether or not a false signal is being generated at idle.

 

Since the DTC states, "Idle Validation Signals Both Low Problem detected with idle validation circuits within APPS", I would double check the wiring condition and connections from the ECM to the APPS - and, maybe try another APPS, if you have one available.

 

Also, I believe that you said you did the W-T wiring modification.  If so, re-check your work regarding Splice #165 - the ground for the APPS, ECM, and other sensors.

 

- John

 

 

 

Edited September 18, 2024Sep 18 by Tractorman