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High Idle Version 2

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I have been looking around at all the million ways you can do this and I came up with another way that seems pretty spiffy. Here's what I have come up with.

First off, in the cab you need 3 single pole single throw switches, which are the simplest form of a switch you can get.

Here is a pic of one.

Posted Image

You install all of those, and hook one side of each switch to a good ground inside the cab. Now run the other side of each switch all outside into the engine bay. One switch will fool the coolant, one switch will turn on high idle, and one will turn on 3 cyl idle. The positive side of each relay is "always on" positive, so you can jumper from one relay to the next. The negative is the switched part.

Now you need 3 relays. The ones I found are as common as pocket lint so are $2 a piece.

These are the ones you need. http://www.parts-express.com/pe/showdetl.cfm?partnumber=330-073&source=googleps

Any auto parts store should have them.

Alright so the contacts on the relays look like this. Labeled exactly the same.

Posted Image

To make the ECT fooler, this is how it is wired.

Posted Image

To do the high idle and 3 cyl relays you do it like this. You might think it goes through the IAT sensor and the 56k resistor when you turn it to 3cyl idle, well it does, but as far as I can tell, 56k or more will do the same thing. So the 56k and the IAT sensor resistance will add up, but produce the same effect.

Posted Image

This way you should only have 3 wires leaving the cab since you should be jumping ground from a place inside the cab. You put the relays somewhere outside the cab like next to the ECM.

So the operation is like this. You hit the ECT switch and now it thinks it is 123F. If you hit the high idle switch it fools IAT into thinking its 28F. If you hit the 3cyl switch it fools it into thinking it is 13F or below since it adds IAT sensor into the equation on that switch. the IAT foolers must only be on separately. If you turn them both on, it will add up all the resistors and do 3cyl.

This means there is no IAT fooler switch or high idle mode switch. There is only a switch for high idle that you turn on or off, and a switch for 3cyl which you turn on or off. The relays are wired so that the normally closed position is the stock position, so if the relays mess up, it will be just like stock. It is also good because they don't need any power to be remain closed. Only when they energize do they switch to the resistors.

The only long wires you should have are the 3 from the switches and the 1 positive wire. You jumper the positive to the other 2 relays. If you mount the relays by the ECM anyways, that will make a short trip to it and you can even splice into the ECT/IAT wires as they go into the ECM.

Operation

Cold Engine Start (Coolant <140°F - Outside Temp > 32*F)

Turn on the high idle switch. Now start your engine. With in about 2 minutes the high idle should start. Once the high idle starts turn off the high idle switch and allow the ECM to monitor the IAT temperatures. As the engine warms up to 170°F it will cancel on its own and idle normally from that point on.

Cold Engine Start (Coolant <140°F - Outside Temp < 32*F)

Turn on the 3 cyl switch. Now start your engine. With in about 2 minutes the high idle should start once it get to 1,200 PRM's the 3 cylinder mode with begin. Once the high idle starts turn off the 3 cyl switch and allow the ECM to monitor the IAT temperatures. As the engine warms up to 170°F it will cancel on its own and idle normally from that point on.

Warm Engine Start (Coolant 140°F-170°F)

You can start the high software with a warm engine. At this point you need to use both the ECT switch and high idle or 3cyl switch. Select the proper idle switch for your weather conditions as in cold start procedure. Once the high idle starts turn off the foolers and allow the ECM to monitor both ECT & IAT temperatures. As the engine warms up to 170°F it will cancel on its own and idle normally from that point on.

Forced High Idle

Turn on both the ECT fooler and the high idle switch. Start the engine and allow the high idle to start. Once the high idle starts turn off the high idle switch but leave the ECT fooler on. This will allow a forced high idle that never ends. To cancel it just turn off the ECT fooler and it will cancel.

So what do you guys think? I can't test out my idea until I decide to get a 24V :lmao:

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Hey,

That would probably work, but you would have to have the three relays under the hood or somewhere and they aren't the smallest and cleanest to mount up in my opinion. I like having the three switch set-up personally with box mounted under the dash that contains everything and can be disconnected in about a minute. That's my thoughts, but it is a cool idea!:thumbup2:

In case you don't understand what I mean here is my set-up:

Posted Image

Posted Image

Thanks,

Winslow

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There is no way I would put that in the cab. I said it would be best to mount it by the ecm, next to the air filter maybe. I hate wires going in and out of the cab, that's why I did this design to go from 8 wires down to 3. Also made it a little simpler since you don't have to turn the IAT fooler on then pick a idle mode. Wish I could build it and take a pic of the end result. Guess I could but it wouldn't do anything but maybe turn the grids on lol.Yeah I read "box mounted under the dash that contains everything" and figured that must have been the setup you were using. Very clean :thumbup2:

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There is no way I would put that in the cab. I said it would be best to mount it by the ecm, next to the air filter maybe. I hate wires going in and out of the cab, that's why I did this design to go from 8 wires down to 3. Also made it a little simpler since you don't have to turn the IAT fooler on then pick a idle mode. Wish I could build it and take a pic of the end result. Guess I could but it wouldn't do anything but maybe turn the grids on lol.

Yeah I read "box mounted under the dash that contains everything" and figured that must have been the setup you were using. Very clean :thumbup2:

Hey,

I understand about the wires, you'll still have wires under the hood that will have to go to the sensors. That's just my thoughts, that's all. I don't have to "pick an idle mode". I just leave the center switch up which is 6 cylinder or if I want 3 cly, I flip the switch down. Pretty simple I thought? All my wires are contained in the two harnesses and are heat shrink wrapped for cleanliness and ease of installation/ removal. It isn't too hard to run them through the firewall, essp. with the bullet connectors left off until inside the truck.:thumbup2:

Yeah I didn't figure you would put the relays inside the cab, but you would have to have them under the hood and I don't like any more clutter than we've already got. Mounted down by the ECM would be okay, but it would be a PITA to install/ remove imo!!:shrug:

And thanks for the compliments on mine; I'm trying to market them for sale as of right now. Just so you know, I'm not trying to bash your set-up, just provide some constructive criticism about it!!:tease:

Mine inside the cab:

Posted Image

Posted Image

Posted Image

Thanks,

Winslow

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I just realized I could use a single pole double throw center off and eliminate a switch, then that would also eliminate people turning both on at once. If both are turned on it would 3cyl idle. It would add the IAT and both resistors so would probably end up saying like -50F lol. But the SPDT would eliminate any issues.Prowelder, I get what your saying. I'd like to make it just to see how much of a mess it ends up being. I do have the wires and sensors so I *could* do it, but it's pointless on mine :lol: I might do it though!

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I hate to say it but found another flaw... I've been studying the connections and there is a crossing of the IAT sensor with the ECM leads... :nono: On your 3 cylinder relay you pulling your signal from the IAT instead of the ECM...:ahhh: So it would but IAT + the resistor 56K ohm...:rolleyes:

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I hate to say it but found another flaw... I've been studying the connections and there is a crossing of the IAT sensor with the ECM leads... :nono: On your 3 cylinder relay you pulling your signal from the IAT instead of the ECM...:ahhh: So it would but IAT + the resistor 56K ohm...:rolleyes:

You mean on 3cyl idle the IAT and 56k are in series? Like I said in my notes...:rolleyes: I said it would add them up and give you even more resistance since it is 56K + IAT but would give the same effect since it will just read as being even colder. All you are doing is getting under the threshold, I don't see why it would need to be an exact 56K.

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You mean on 3cyl idle the IAT and 56k are in series? Like I said in my notes...:rolleyes: I said it would add them up and give you even more resistance since it is 56K + IAT but would give the same effect since it will just read as being even colder. All you are doing is getting under the threshold, I don't see why it would need to be an exact 56K.

Hey, My worry would be the computer thinking it is too cold and throwing a code. Not sure if it would or not, but that would most likely show a pretty cold temp!:stuned: Later, Winslow

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ah the general motors 5 pin relay the answer to all the great wiring problems in the world. :2cents:

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i heard of a single switch high idle from some else. he's been slow to post a diagram, but i did gleen that he uses 3 dpdt relays, and a dpdt switch. i've been thinking about how it would work off and on, to try and figure it out, but if someone has any ideas, just hop on in. thanks guys

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i heard of a single switch high idle from some else. he's been slow to post a diagram, but i did gleen that he uses 3 dpdt relays, and a dpdt switch.

i've been thinking about how it would work off and on, to try and figure it out, but if someone has any ideas, just hop on in.

thanks guys

Been trying to figure it out. No matter how you do it, you end up with half the features of Mike's design. I'd like to figure out exactly what this DPDT switch did and if it had a center off. The fact is, you can only do 2 of the following things with one switch as far as I can tell:

[*]Forced High Idle

[*]3 Cyl Idle

[*]High Idle

[*]Ability to turn IAT off and leave ECT on

The forced high idle is something you can't do with one switch if you still want 3cyl idle. Not safely anyways. You have to turn the ECT back on so it doesn't end up overheating.

I also have no idea why he needed 3. You can do any of the 2 things that he would be able to do with 2 of those DPDT relays.

If you can get more info, I could figure out more of what he did. But I think no matter what, the setup is limited in functionality and/or safety features. What good is forced high idle if it will overheat when your not looking..

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i hope it's okay to paste this here, here is what he wrote:

Sorry guys. I've been getting buried with questions about it. The short story is it utilizes three DPDT relays and a DPDT Center Off switch in the cab. The switch just energizes different relays depending on the position. The center off releases all the relays so it can read the sensors instead of the resistors. It also fails to the off position so if something does go wrong, the truck operates in stock form. Also dosen't keep the relays energized while the truck is off to eliminate current drain, and wear on the relays. I promise I will get a formal drawing completed. Posted Image

I can start high idle or 3cyl high idle at any time. I can start the truck in stock form and flip the switch and it will go to high ilde or 3cyl high idle. I can do this as many times as I want. With my turbo timer on my Edge set to 300 I can also use it as a secure idle method when going into a store or something. Set the high idle let it get going and it will keep the EGT's above 300. I can pull the key and walk away. If somebody gets in and hits the brake or accelerator the truck dies.

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i hope it's okay to paste this here, here is what he wrote:

Sorry guys. I've been getting buried with questions about it. The short story is it utilizes three DPDT relays and a DPDT Center Off switch in the cab. The switch just energizes different relays depending on the position. The center off releases all the relays so it can read the sensors instead of the resistors. It also fails to the off position so if something does go wrong, the truck operates in stock form. Also dosen't keep the relays energized while the truck is off to eliminate current drain, and wear on the relays. I promise I will get a formal drawing completed. Posted Image

I can start high idle or 3cyl high idle at any time. I can start the truck in stock form and flip the switch and it will go to high ilde or 3cyl high idle. I can do this as many times as I want. With my turbo timer on my Edge set to 300 I can also use it as a secure idle method when going into a store or something. Set the high idle let it get going and it will keep the EGT's above 300. I can pull the key and walk away. If somebody gets in and hits the brake or accelerator the truck dies.

So it seems like it will turn high idle on or 3cyl any time, and temp. This leads me to believe that the switch in either position runs both the ECT and IAT foolers at the same time. I am not sure Forced High Idle has to have the IAT turned off or what the purpose of that is. I thought Mike turned the ECT fooler off to monitor engine temps but I guess it is IAT fooler he turns off. Nevertheless, it would work, I think, I just don't see why he needs so many fancy relays. I will wire it up and show you how I think he did it. I believe he uses the ECT resistor for both sides of the switch in conjunction with either the 3cyl or high idle resistor. So it fools the IAT and ECT if the switch is flipped in either direction, but uses different idle resistor.

--- Update to the previous post...

Here is how I think it was wired, though I still think he way overdid the relays. I took it down to the bare minimum.

The switch selection on "Other" is exactly the same as this one except the 56k resistor is a 39k one..

Posted Image

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i found a dp3t on-on-on switch looking at a catalog at work (it has been around for years and i never looked at it before). if i'm thinking right, could that switch work safely with a single switch high idle? the pic is small, but it seems to have twelve terminals on it.

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i found a dp3t on-on-on switch looking at a catalog at work (it has been around for years and i never looked at it before). if i'm thinking right, could that switch work safely with a single switch high idle? the pic is small, but it seems to have twelve terminals on it.

Yeah you just need the relays. Mike's way doesn't involve relays so there is a little bit less work/wiring. Yeah it has 12 terminals. 2 are for the coil and the rest run relays and such.

--- Update to the previous post...

If you can't see my schematic very good that is actually a scaled down picture. The full size one is here: http://www.mopar1973man.com//isx97/Other/HighIdle3.jpg

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but doesn't the dp3t make relays unessary? one side of the switch is "old load", and the other side is "new load"? since there are three "throws" that takes care of all three situations with the ect and iat, right? i might have to pick up that switch and put the multimeter to it. so fool ect in both cases by crossing to both sides, and fool iat separatelyi've never dealt with such a complex switch. and it isn't the right switch, it will sit in my spare electronics drawer for something else i guess. super fast response, i'm sitting drinkin' and am answerin again already! lol

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but doesn't the dp3t make relays unessary? one side of the switch is "old load", and the other side is "new load"? since there are three "throws" that takes care of all three situations with the ect and iat, right? i might have to pick up that switch and put the multimeter to it.

so fool ect in both cases by crossing to both sides, and fool iat separately

i've never dealt with such a complex switch. and it isn't the right switch, it will sit in my spare electronics drawer for something else i guess.

super fast response, i'm sitting drinkin' and am answerin again already! lol

Do you want all the features? I will have to look at it a little more and see if you can get by without relays, never thought about doing it without them, relays are just too fun for me to ignore :lol:

--- Update to the previous post...

You have one of these switches? Should connect like this anyways.

Posted Image

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if i can, it would be great, even if there were some caveats. i really am sold on the single switch, and without relays would take the cake! you know? simple and sweet, an improvement on the oringal. the perfect place for one switch in my truck that would be out of the way but still handy is in that garage door opener thing in the overhead console. my truck is too old and primitave to have the overhead display, lol. and i've modded all the other places i've seen people put them (stick, dash). i always told myself i'd take care of this mod before it got cold, but now it's almost too late again, this is my second winter with this beast.

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if i can, it would be great, even if there were some caveats. i really am sold on the single switch, and without relays would take the cake! you know? simple and sweet, an improvement on the oringal. the perfect place for one switch in my truck that would be out of the way but still handy is in that garage door opener thing in the overhead console. my truck is too old and primitave to have the overhead display, lol. and i've modded all the other places i've seen people put them (stick, dash). i always told myself i'd take care of this mod before it got cold, but now it's almost too late again, this is my second winter with this beast.

It would be easy to do a single switch. Just solder on a 39k resister to and the four wires for the IAT harness and you would have a single switch high idle.:thumbup2:

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Get a pic or something of the switch you have. I want to be sure of what I am working with. I will see what I can figure out since you want all the features.Single switch high idle is easy but all the features make it a little harder.

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Get a pic or something of the switch you have. I want to be sure of what I am working with. I will see what I can figure out since you want all the features. Single switch high idle is easy but all the features make it a little harder.

Yeah that's true, but in my opinion, just not practical.:surrender:

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