High idle when AC fan kicks on. Possibly APPS pedal?

R

Resolute_weldin

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So I moved my batteries from under the hood to in the bed. All connections cleaned and grounded to frame. Batteries wired straight to starter and from starter to fuse box. Truck sat unhooked for over a month. When I turn the AC on the truck idles up to about 1300rpm. I can see because of my programmer that the TPS is going to 4-6% when the idle goes up. So what could be causing the apps to see voltage when the fan is turned on?
 
The first thing that comes to mind is the cold weather high idle, it'd have to be confusing the iat sensor. I don't know if that would change the apps reading though, because it's done between the ecm and pump.

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Could a pump going bad cause this kind of problem? With my programmer I can see IAT readings and everything. It isn't cold here in Texas ATM.
 
So I tried something on a whim remembering that the truck will idle without the apps plugged in, I unplugged the apps and all of my symptoms are gone. Truck idles and doesn't change when lights are turned on, fan, brakes, etc. This would point to bad apps?
 
I would guess it would point to noise on a line somewhere. If it didn't do it before, and did it right after, I wouldn't think your APPS went out during the battery swap.....unless I'm reading it wrong....or you shorted something while doing the swap and it fried the APPS. The APPS is simply a potentiometer with a few switches for high idle in it. It really is a dumb sensor. So, this happened the first time you started the truck after it setting for a month just after you did the swap?
 
I've dorked with the APPS several times on the old truck. I swore there was an internal schematic of it....but I can't seem to find it. I'll keep looking.

Edit: Posting the connector pin-out in case you need it.

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More junk to spark thought.....

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When the APPS hits bottom, it tells the ECM when it is at "idle." If the AC turns the high idle on, you either have a wiring issue or something else is triggering the cold weather mode.
 

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I wonder if running a direct ground from the apps to the battery would tell you anything? Dodge apparently doesn't know how to shield wires so noise in the grounds will cause weird stuff. For example, my alternator being worn out would cause my a/c to switch off lol.

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