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She Don't Smoke!
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OBD-I High Idle Setup Guide
For use on 1994-1995 6.5L Trucks
(For 1996+ OBDII Trucks Click Here)

This mod will come in handy for faster warm-ups in cold weather and if you idle your vehicle a lot. People say if a Diesel engine idles for long periods of time under 1,000 rpm it could possibly wash down the cylinder walls. The high idle will raise rpms to approximately 1100 rpms.

Parts Needed:
  • Computer Pin Terminals [OEM #12089649]
  • Approximately 16ga wire or bigger and connectors [$5 for a small spool]
  • Add a Wire Fuse Tap [$7 - Advance Auto - 5080114 (BP/HHH) ]
  • Rocker or Toggle Switch [$5-10 part store]
Step 1:
Remove Dash Bezel
You can remove the dash bezel by dropping steering column as low as it will go, putting gear shifter in 1st (on automatics), and pulling the cup holder out a little bit. After that pull at a corner and pull all the way around the bezel. The only thing that holds the bezel on are the clips.
Once all the clips are lose you can unplug the headlight switch, cargo switch, and 4x4 switch (if equipped).




Step 2:
Getting to the Computer
Open up your glovebox and empty it out. Once that is done, push in the tab on each side (see picture). After the top is loose, drop the box a little bit more and pull out. You will now see the computer on the right side.




Step 3:
Installing Switch
Chose a place to install your switch (see pictures for mine). Be careful when you drill your hole for the switch. Its basically a one shot deal, because if you mess it up its going to be there and you can't really hide it.
After the hole is made, install the switch in your dash.



Step 4:
Wiring the Switch
Using the fuse tap kit, plug into a fuse that only has power when the key is on (I used the radio fuse for this) and run the wire to the switch. Next you will want to take enough wire to run from the switch to the computer with a little slack (see picture where i routed mine). Connect wire to switch and run along inside the dash and to the computer behind the glovebox.




Note: When using a switch that has a light in it, if you want the switch to light when in use you will have to ground the switch as well.


Step 5:
Connecting to Computer
Once you have ran the wire to the computer, strip the end of the wire and connect the terminal pin for the computer. Next, remove the center pink 24pin connector by squeezing the lock tabs and pulling.

Remove the lock on Row A on the top part of the connector. Place the wire with the terminal pin into slot A6. After you complete that remember to put the pin lock back in place and then connect the connector back into the computer.



Step 6:
Finishing Up
Once you think you have everything hooked up how you think it should be. Place your dash bezel up where it should go and connect the wires (including your new high idle switch). Start your truck and test the high idle. If it works, then go ahead and clip your bezel back into the dash and install your glovebox. If it doesn't work you will need to make sure all your connections are good and that you are getting 12v to the switch and with the switch on you are getting 12v to the pin terminal.

Some more Pictures:




Note: Always be careful when probing any wires going to or from the computer!
Note: From what I know, OBDI trucks do not shut off High Idle when brake is depressed or truck is in gear.
 

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I know the dash is different on a '94, is the computer plug still the same?
 

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She Don't Smoke!
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Discussion Starter #3

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Good write up, It is pretty much the same for the 94's just diff dash setup.

You Are right, the high idle does not disengage when the brake is pressed or put into gear.
 

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woohoo Thank you! more goodies to put on the dash :D:D:D
 

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Great write-up Mike, bought time we had one for the OBD-I guys!!
 

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Bout time we have a OBD1 high idle how to :D:p:

Good job Mikey.

Edit: Great minds thinking alike Matt? Lol
 

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hello this might be a stupid question but will this work on a 93 it has the mechanical ip and if no is there a way to do it on it
 

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thanks green i was waitting for some to put that on here know i can get my done
 

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She Don't Smoke!
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Discussion Starter #11
hello this might be a stupid question but will this work on a 93 it has the mechanical ip and if no is there a way to do it on it
This will not work on '93 trucks. Not sure if there is a way to do it either.
 

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If the '93 is anything like my '86 you can... just put 12v to the plunger solinoid on the IP that is used for cold starts. I'm not sure what it's called. :(

Bill
 

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Green Machine, what do you mean by wash down the cylinders if you let the truck idle for a while. I know people who just let them run for a while and this seems to be the norm, expecially for warmup. Thanks.

Jim
 

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She Don't Smoke!
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Green Machine, what do you mean by wash down the cylinders if you let the truck idle for a while. I know people who just let them run for a while and this seems to be the norm, expecially for warmup. Thanks.

Jim
I'm talking about letting the truck idle for hours at a time. Most warmup periods during the winter for our trucks should be 3-10 minutes. I let mine sit and run for 3-5 on really cold days. down to about 35 i let sit only for a couple minutes and drive easily through town and by the time i get out of town its up to about 180.
 

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i have a 95, and i have wanted to do this for a while, do i have to run to the fuse box? or can i just splice into it from one of my radio power wires near the deck? i got enough wires in the fuse area from a previous owner, and i dont like that method just wondering if i can do that instead. Also i dont know where to get the pins for the computer, is there an alternative way of splicing into that too? or is this generally the only way?
 

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I got my pins at the "recycled parts store". I cut a plug with wires from a parted out truck. I still have 10 or 15 left. If you PM me I could send you one for free.
 

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She Don't Smoke!
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Discussion Starter #18
i have a 95, and i have wanted to do this for a while, do i have to run to the fuse box? or can i just splice into it from one of my radio power wires near the deck? i got enough wires in the fuse area from a previous owner, and i dont like that method just wondering if i can do that instead. Also i dont know where to get the pins for the computer, is there an alternative way of splicing into that too? or is this generally the only way?
You don't "have" to run to the fuse box. But like any manufacturer they don't "recommend" splicing into other wires. But if you splice into the radio wire, just add a fuse the high idle wire for extra protection ;). From what I know you have to use the pins for the PCM so you get a good connection at the computer.
 

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You don't "have" to run to the fuse box. But like any manufacturer they don't "recommend" splicing into other wires. But if you splice into the radio wire, just add a fuse the high idle wire for extra protection ;). From what I know you have to use the pins for the PCM so you get a good connection at the computer.
alright yeah, its always good to put fuses in, i have two radio harnesses ( one for old alpine deck and one for my new deck, works fine) and i got two fuses in there so i can tie into of of them, will work alright i think, and i am gonna try and get those pins then. Thanks for the help everyone though! this is a great forum on these trucks! Very impressed!
 

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Thanks for the How to pictorial with pictures...it made the job that much faster for me to do. I did it on my 95 and it works great!!
Only thing is that it doesnt kick down the idle when pushing on the break pedal and/or putting it into gear....I can live with that.
 
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