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post #1 of 2 Old 01-12-2009, 09:26 AM Thread Starter Fanatic
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aic controller

ok can someone help me understand this all?[QUOTE][/QURob Milnes explains the benefits of an Auxiliary Idle Controller (AIC) and explains how to build a cheap alternative to the factory AIC.

1999-2004 $10/$15 Auxiliary Idle Controller (AIC)
This modification will allow you to manually set and adjust the idle speed of your 1999-2004 7.3L Power Stroke without spending $400-600 for the factory AIC. The $15 AIC option will add a indicator light to let you know the AIC is on. The 1999+ trucks will high idle automatically during the colder months when the oil is cold, but an AIC is handy for:
avoiding wet stacking, caused by idling after the post turbo EGT falls below 275 degrees
getting full power out of the AC during pit stops
jump-starting another vehicle without having to sit in the truck
impressing your friends with your awesome electrical know-how
It should not be used as a low speed cruise control for safety reasons. Neither the $10 or the $15 will disengage if the brakes are applied. If there is enough interest, I will design an AIC that can only be used when the parking brake is set.

Why you might want to buy the Ford AIC
It can automatically put your truck into high idle when the parking brake is applied
It has a digital display
It will hold an exact RPM. The $10/$15 will vary speed slightly as the engine warms/cools
It has a warrenty
more info
If you're still with me, here's how to build your own.

Time required
About 1-2 hours

Items needed:
R1 potentiometer with linear taper (see Table 1 for values)
R2 potentiometer with linear taper (see Table 1 for values)
2 knobs for above potentiometers
Double pole, single throw (DPST) switch
16 guage wires (4 colors: red, green, brown, grey)
Electrical tape
Heat shrink tubing
Values for R1 & R2 potentiometers 1999-2002 7.3 L 2003 7.3 L 2003 6.0 L 2004 6.0 L
R1 5K 50K ? ?
R2 5K 10K ? ?

NOTE: This article is still a work in progress, so if you have done this to your truck please send me the R1 and R2 values you used.
When I installed my AIC on my 2003 7.3L, I found it needs vastly differnt R1 and R2 values than anything posted out there. I have the feeling that the 6.0 L's would need different values as well.
Extra items for $15 AIC:
LED and holder
1N4004 Diode
680 ohm resistor
16 guage wire (red, black)
Tools required:
slot screwdriver
wire strippers
Soldering iron and solder
adjustable wrench
allen key
hack saw
drill, dremel tool, etc as required to mount controls
$10 AIC procedure
Figure 1

$10 AIC diagram
Locate the accelerator pedal and remove the 3 fasteners to remove it.
Locate the wires with the following colors in the wiring harness connected to the pedal:
Red w/ yellow tracer
Red w/ green tracer
Brown w/ white tracer
Grey w/ white tracer
Strip and solder approximately 2' (or more depending on where you want to mount the controls) of the following wires to the above wires:
Connect the yellow and green leads to one pole of the DPST switch (so that the yellow and green leads are electrically connected when the switch is on). Check with the multimeter.
Open fuse panel access cover on the driver's side
Connect the brown lead to the left terminal of the R1 potentiometer. Connect more brown wire to the center terminal of the R1 potentiometer.
Cut off excess post on the R1 potentiometer and mount it behind the fuse panel access cover. Install the knob with an allen key.
Connect the brown lead from the center of the R1 potentiometer to the other pole of the DPST switch.
Run a grey lead from the last terminal of the DPST switch to the left terminal of the R2 potentiometer.
Connect the grey lead from the accelerator pedal to the center terminal of the R2 potentiometer.
Ensure that all connections are not grounded or touching.
With the mulimeter, set the R1 potentiometer to half and the R2 potentiometer to 0 ohms.
Set the DPST switch to off.
Test and Tune
Start the truck and allow to idle for 1 min. Flip the DPST switch to on. Adjust the R1 potentiometer until idle speed is approximately 1100-1200 rpm. The full range of the R2 potentiometer should change the idle speed ~ 100 rpm. Once you are satisfied with the idle speed and range of adjustment, tape down the knob on the R1 potentiometer. Flip the DPST to off. Idle speed should return to 600-700 rpm.

final installation
Mount the DPST switch and R2 potentiometer as desired
Reinstall accelerator pedal
Heat shrink and/or tape all electrical connections and zip tie loose wires
Reinstall fuse panel access cover
Grab a cold one and admire your work
Take a picture of your install and email it to me!
$15 AIC procedure
This version adds an LED indicator that lights up with the AIC is in use.

Figure 2

$15 AIC diagram
Follow steps 1-13 of the $10 AIC procedure.
Cut the green lead wire 1-2" from the DPST switch.
Solder the red lead and the anode (+) of the diode to the green lead coming from the DPST switch (double check this step)
Solder the Cathode (-) of the diode to the remaining green lead.
Solder the red lead to the (+) terminal of the LED
Solder the black wire to the (-) terminal of the LED
Connect this black lead to ground
Test and tune per $10 AIC
Use the LED holder to mount the LED during the final installation phase.


Wet Stacking = occurs in diesel engines run with little or no load for an extended period of time. Cylinder walls become cold and unburnt fuel will accumulate on them. This will cause damage if done often enough.
Thanks to DixieDiesel for the idea.

ok first what is a r1 potentiometer with linear taper and r2 potentiometer and where do get it?lol dpst switch?led and holder? want to do the mod but need to know the parts to get lol
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post #2 of 2 Old 01-12-2009, 04:54 PM Thread Starter Fanatic
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come on no one knows this??
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