Homemade High Idle Control
 

If I could determine the resistance of the accelerator pedal at around 1000 rpms, couldn't I rig up that resistance and switch it on in the accelerator pedal circuit to make the truck go to high idle? Any flaws in my thinking?

These are instructions for the obs, it might work for yours

AuxiliaryIdleController

AIC MOD

by Sparky
Ok to start off with you will have to go to Radio Shack or similar store and get some parts.

Single Pole Single Throw Switch. Radio Shack pt# 275-612
5K Linear Taper Potentiometer. Radio Shack pt# 271-1714
Linear PART # for the 2K is Radio Shack pt# 900-8587
2 Single Pole Double Throw Auto Relays Radio Shack pt# 900-2391
2 Wiring Harness Plugs Radio Shack pt# 900-2396
18 Gauge Wire
SOLDER
Wire Ties
Butt Connectors
Soldering Gun
Safety Glasses

STEP 1 Switches

Find a power source that is with the key.
Run a wire from there to one side of the switch.
From the other side of the switch run a wire to the coil terminal of both relays
From the other side coil terminals on the relays run a wire to the parking break switch wire. (There is only one wire on the parking brake.)

STEP 2 Idle Validation Switch (IVS)

As you look at the throttle pedal you will see a switch on the left side with 2 wires going to it. The wires are taped together carefully un-tape them so you can work with the wires. I used a razor knife to cut the tape, but be careful not to cut the wires. (There should be a red/orange with and a brown wire, unless they changed the color code of these wires.)

Cut the red/orange wire leaving plenty on the switch side so that you can splice onto it. The red/orange wire that is going into the wire bundle needs to get hooked to the common side of one of the relays.

The other red/orange (the one attached to the IVS) goes to the NORMALLY CLOSED CONTACT (NC) of the relay. Now take a wire from the NORMALLY OPEN CONTACT (NO) and run it over to the brown wire by the IVS, you will just tap onto this wire so you don’t need to cut it. Just take some of the insulation off and solder it on, then tape her back up.

STEP 3 The other Relay and the Throttle Position Sensor (TPS)

Throttle Position Sensor (TPS) is located on top of the pedal and has 3 wires going to it. Remove the tape to expose the wires. (There should be a brown/white wire and a gray/white wire.)

Cut the brown/white wire, leaving enough to work with by the switch. Hook the end up that goes back into the wire bundle to the common side of the other relay.

Take the side that goes to the switch and hook it to the NORMALLY CLOSED CONTACT (NC) of the relay.

Take a wire from the NORMALLY OPEN CONTACT (NO) of the relay and go to the left terminal on the POT.

Now take a wire from the center terminal of the POT and tap it into the gray/white wire.

Tape up all the bare wires and enjoy

Man! I love this site! This info is what i questioned about 6 months ago.
Thanks ForemanES

Very cool, this thread needs to be posted for all to see somewhere.

Awesome. Thanks You mentioned 'obs' what is that.

OBS= Old Body Style. The 1994-1997 powerstrokes were considered "Old Body Style"

On the 01's the wire colors have changed. PM me with an email address and i can send you a schematic of the 1 and 2 plug varieties of the pedal connector.

On the IVS it looks like the Red orange is now red/yellow stripe and the brown is now red with light green stripe

On the TPS unless the have moved the wires the colors are the same

Thanks amiller93 for jumping in and "updating" the wire color. I figured it would be close to the same thing. I have to give you guys the site this came from, even if it is for the older trucks. There is A LOT of info on there and some might help you guys out with cheap mod instructions. (click here)

Anybody Tried this yet ???

How to activate the High idle function on a 2004 Powerstroke.


This will increase the engine idle speed to 1200rpm as long as the transmission is in Park or Neutral and your foot is not on the brake pedal.

This info is valid for 2004 Powerstrokes with the automatic transmission. I'm not sure if the manual transmission PCM's have the PTO idle up function software installed.

This procedure connects two body harness wires together with a switch. When the switch is activated battery power from one wire is sent to the PTO control wire telling the PCM to raise the idle speed to 1200rpm.

Here is what you do.

Look up under the dash between the steering column and the parking brake pedal. You will find a wiring harness behind the parking brake handle with a bunch of wires coming out of the harness that have the ends sealed off with charcoal?? colored heat shrink tubing.

If your not sure what you are looking at, look at the three wiring harnesses that come through the firewall to the left of the steering column shaft into the passenger compartment. The top harness is big, the middle harness is smaller than the top harness and the last harness closest to the floor is smaller still. The wire you are looking for comes out of the the middle harness where the harness routes up to the dash directly behind the parking brake handle.

One of these wires will be Light Blue with a Yellow stripe. This is the PTO function wire from the PCM. Placing battery power (battery positive) on this wire will command the PCM to raise the idle speed to 1200rpm as long as the transmission is in Park or Neutral and the service brake is released, meaning your foot is not on the brake pedal and the brake lights are not activated.

The other wire you are looking for is a White wire with a Light Blue stripe. This one is also easy to find. While looking under the dash direct your attention to the black OBD II datalink connector mounted to the lower part of the dash to the right of the steering column. This connector is what a service tech uses to hook up a scan tool which is needed to communicate with the vehicle PCM in order to check engine sensor data, engine trouble codes and to REFLASH your PCM.

Anyway, look at this black connector and follow the wiring harness from the plug back up and inside the dash. Along the harness not too far up from the plug you will find the White wire with a Light Blue stripe included in the bundle of wires but the wire just stops short of the connector. Yes the wire does not plug into any one of the ports of the datalink connector.

This White wire with a Light Blue stipe is your positive battery source wire that you will connect to the Light Blue with a Yellow stripe PTO wire through a switch.

Purchase some wire, a switch that has a illuminating paddle switch lever and some female crimp connectors and some butt connectors.

Use the wire and butt connectors to extend these vehicle wires so you can mount the switch under the dash to the right of the OBD II datalink connector. Crimp the female crimp connectors on the end of each wire so the wires could plug into the male terminals of the switch.

So far you have used two wires connected to the switch. The illuminating paddle switch has three terminals. The last terminal is a ground connection that is used so that when the switch is turned on the switch paddle illuminates.

it look easier then making a aux. idle control from but i tried it and it wouldnt work :( lol

The 04 is a 6 leaker, totally different motor and PCM than a 7.3.

When he says "wire bundle" is that the bundle going through the fire wall?

"Cut the red/orange wire leaving plenty on the switch side so that you can splice onto it. The red/orange wire that is going into the wire bundle needs to get hooked to the common side of one of the relays."

I just signed up so if I do something wrong here I hope the administrators will forgive me. I see this is an old thread & it was linked to me by a member of thedieselstop.
I have some schematics for a DIY, AIC that I am wanting more information about. I have read just about ALL the other posts/instructions and find NONE of them to be as detailed as mine are. But I still have questions and would NEVER hook it up or advise anyone else to until ALL the questions are answered and OTHER people that are smarter than myself have input into what I have designed. I hope it's O.K to insert a link to the thread on the other site as it has my schematics photos and other thoughts & information in the thread. Just not the answers I am seeking to make a confident decision about going through with the project. By the way, You can do this for $20 or less in parts. That's why I "don't just buy the ready made Ford AIC's ($300 to $600) or any made by others ($79.99)!
Maybe someone on here can shoot the breeze with me on the merits of this design/project and not get all hung up on "why not just buy one" or "it (might) fry your PCM". It either WILL or it Won't. Let's figure it out together and not play guessing games! Here is the link. I hope that is allowed here. It's late and I just don't have time to read all the rules. DDT

Maybe if I ask about AIC in another way... - Page 2 - Diesel Forum - TheDieselStop.com

You might be able to combine MY schematics from the other site I linked to with the directions in post #2 above. I have also read that post & it seems like it is either describing my plans exactly or very close. The point is....A picture is worth a thousand words. I think my schematic would compliment those instructions very well.
Just take a look. Then you will be able to (see) how there are TWO (separate) circuits & how the relays flip/flop between them when activated.
But there are vehicle year and wire color codes to be considered, as well as any changes to PCM's and voltage/resistance values.
I would be very careful until (we) have some questions cleared up.
here is some (basic) info as I understand it....
There are TWO switches (well one switch & one sensor) that must be delt with here. The IVS (Idle validation switch) & the TPS (throttle position sensor).
The IVS is easy. It's just a switch. On/Off. BUT know it is a 12 volt switch!
So you cut the OEM wire as per my schematics and redirect the RETURN 12 volt signal wire through the RELAY (as per my schematic). Obviously the relay's need a 12 volt supply line to operate. Simply find a (key on) 12 volt line to wire to a on/off switch and to one side of the relays coil terminals. On the IVS switch you can also jump a wire over to give the required 12 volts to the other terminal on the relay for when the AIC is activated. DO NOT JUMP 12 VOLTS on the TPS relay!!!
The TPS is fed a 5 VOLT supply from the PCM and uses voltages between ZERO and 4.875. SEE SCHEMATIC for TPS.
So the IVS is EASY!
For the TPS (there are 3 wires) (you might want to Google Potentiometers if you don't know anything about them). You will want to tap a line into the OEM 5 volt feed from the PCM to the TPS. (Color codes are going to vary with year & make of vehicle). So this is where either someone will have to chime in or you will need to assure yourself which of the 3 wires is 5 volts inbound to the TPS. This tapped wire will be directed through the potentiometers and will then be directed to the second relay being used for the TPS. (SEE SCHEMATIC). One of the other of the 3 wires on the TPS is the RETURN wire to the PCM that has a variable voltage as you push & release the throttle pedal up and down. This one will be cut and redirected through the relays "normally closed" terminals. (SEE SCHEMATIC). Then another wire will return back to where you just cut and finish the return path back to the PCM.
In other words....You have simply cut the return to PCM wire (leaving two loose ends). You redirected the wire coming out of the TPS through to one of the terminals on the relay. (inside the relay THAT terminal is "normally closed" or "making contact with terminal #30. (SEE SCHEMATIC). You now connect a wire from #30 back to the only other wire hanging loose that you just cut. That is the one back to the PCM. This is all being done so when the relays are NOT activated, The voltage of both the IVS & TPS will be doing EXACTLY the same thing they did before you cut & rerouted them. They just now do it through the relays. You could stop here and never finish the job & no harm done!
The only questions left now are about EXACTLY what the resistance & voltage values YOUR make & model year vehicle expect to see through the TPS. This is where choosing the proper Pots. and how they should be wired becomes a question (at least for me). There is a "chart" on line here somewhere that gives the values for a 2008 superduty. From my reading of it.....It seems IDLE is achieved when there is an OPEN CIRCUIT. That would mean that when the throttle pedal is in the full back (Idle position), The 5 volt supply wire INTO the TPS is not being directed through or making any contact inside the TPS to allow any voltage to exit on the RETURN wire back to the PCM. So IDLE= OPEN CIRCUIT.
Then as the throttle pedal is just beginning to be depressed, electrical contact (continuity) is made inside the TPS and a voltage is sent through the RETURN line to the PCM. (probably the center wire). According to the 2008 year diesel chart that I have seen, that voltage varies between 0 to 4.4875 volts.
This is what you need to "trick" the PCM (return line) into through your pots.
But since we are only wanting to adjust for a high idle and NOT WOT, we are only trying to duplicate the low end of the range. From the chart it would seem that the "low end" is the one with the lowest voltage through the return line and therefore the highest resistance to achieve that low voltage.
Again, A question would be......IS idle achieved at OPEN CIRCUIT or ZERO voltage return to PCM???
Unfortunately I did not include a photo or link to the chart I keep mentioning in my linked thread on the (other) site. I don't think it would be hard to find.
I hope this along with the schematics helps others AND I hope more importantly OTHERS will correct anything that is WRONG with this design or information.
These ARE NOT instructions of what you should do. This is an explanation of how (I) believe a DIY, AIC can be made following (my) schematics.
ALL CONSTRUCTIVE INPUT IS WELCOME & DESIRED! DDT

I believe I have put this out there before. *WARNING*

We hardly ever speak of our mistakes. I've make a thousand or so in 30 years.

But, I had a neighbor about 10 years ago who begged me to do this to his 99. I tried to get him to buy a DP Chip with it programmed. He said he didn't have the money... bla...bla..bla.

He brought me the instructions and all the parts.

I was very reluctant but, his persistence clouded my better judgement.

I get the entire thig wired. Works great. Had everything loose before final assembly. My daughter had come out to tell me dinner was ready. It "spooked me" while I was holding the relay and I let it go; touched ground or another wire somewhere along the way swinging.

BOTTOM LINE: I bought an $500 PCM. Actually, I had a PCM and just flashed it at work. It was a take-off. But, still I'm out of pocket because I didn't have it to do another job along the line somewhere I'm sure.

That's why I put the *WARNING* at the top.

If anybody wants to go with the OE solution, looked into this a few months ago and seems the AIC module came *way* down in price. Still a good bit more expensive than a DIY solution, but it should simply plug-in. IIRC there are two varieties to the AIC where one also controls the RPM's based on voltage needs in addition to the PTO setting.