APPS information

Rollin Coal

Rollin Coal

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Oct 25, 2008
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I've been wanting to ditch my APPS for a while now, and I think its about time to do it.

Im going to most likely make a pedal mounted TPS, but i may make something that mounts to the firewall and uses a small cable.

Heres what I gathered so far.

APPS has 6 wires

APPS 5v Supply
APPS Signal
APPS Ground

IV Off Idle
IV Idle
IV Ground

2 completely separate circuits, starting with the APPS

Supply - 5v supply that all the sensors get
Signal - From what I've read the ECM is looking for ~0.5v (idle) to 3.5v (wot)
the idle voltage is COMPLETELY dependent on the apps, it can be 0.3, 0.7, more, less, in between, whatever. So does the ECM have a high and low limitation for the idle voltage? I'm sure if it sees no volts, or very low it throws a code. Also, where is full fueling going to come into play, 3.5v, or can it be pushed past, will 4v trick the computer or just trip a code? I assume the Idle Verification side of the APPS exists because of the varying idle voltage.

This side is simple, ground Off Idle pin any time the accelerator moves off idle, and ground the Idle pin at idle. A SPDT momentary switch should accomplish this fine, but I'm wondering if telling the ECM that the truck is Off Idle, while actually at Idle would allow for a home made high idle. If it does, I may just put a switch on the dash for that. Are there any known negative effects of telling the ECM that the truck is off idle while the truck is idling?
 
It's ugly. LOL honestly though I wish I could get rid of mine. One more piece of clutter under the hood.
 
Rollin Coal said:
Signal - From what I've read the ECM is looking for ~0.5v (idle) to 3.5v (wot)
the idle voltage is COMPLETELY dependent on the apps, it can be 0.3, 0.7, more, less, in between, whatever. So does the ECM have a high and low limitation for the idle voltage? yes I'm sure if it sees no volts, or very low it throws a code. yes Also, where is full fueling going to come into play, 3.5v, or can it be pushed past, will 4v trick the computer or just trip a code? yes I assume the Idle Verification side of the APPS exists because of the varying idle voltage. and to prevent the condition of added resistance to the harness through wear and tear, making the engine accelerate

This side is simple, ground Off Idle pin any time the accelerator moves off idle, and ground the Idle pin at idle. A SPDT momentary switch should accomplish this fine, but I'm wondering if telling the ECM that the truck is Off Idle, while actually at Idle would allow for a home made high idle. If it does, I may just put a switch on the dash for that. Are there any known negative effects of telling the ECM that the truck is off idle while the truck is idling? You'll have to also add some resistance to the throttle position at the same time to make the Rev's come up. You'll probably have to play around with it a while to get it exactly where you want it.
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I think im going to have a pretty cool little set up for this. Ill post back once i make something
 
Is it basically a potentiometer?
How many "wipers" does it have?
 
How about a pedal unit out of a semi? Be cheap from a junkyard, then hack it up. I imagine the values might be a match depending on the motor it had.
 
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