I think your probably talking about relay. You can hook up a relay to open a circuit when voltage is applied to it. I guess I would need to know exactly what your looking to do inorder to give you an answer.

 

Yeah...i can see the relay working fine. BUT once you take your foot off the brake, the High Idle would start back up. I guess what i want to do is have a brake over-ride like the crusie control. You set the idle and if you hit the brake it shuts it off until you hit the button to turn it back on (Not when you take your foot off the brake)

I guess like a conditional switch of sorts. It works when you push the button to turn it on, and then shuts off when you tap the brake until you push the button to turn the system back on.

 

It would basically be like the 3 relay TC switch. It would work with 2 additional relays if I have it setup in my mind right. Take a look at the 3 relay mstery switch and youll see what I mean.

 

I was thinking this was put this in the cab and made to be an adjustable idle controller. This makes more sense to me now, it is an electronic controller for a fixed idle position.

 

OK....posting it here since we mentioned it......

 

I may need more time to look at this to translate into what i want to do with it...but i don’t see how this would give me an override when the brake is depressed unless getting a sustaining voltage to keep the relay in the off position. The ECM in this schematic has some weight on how the system works (UNLESS you totally bypass it with the manual override switch).....again....ill look at it some more.....

I don’t know....I might be shooting in the dark here and trying to overcomplicate a simple thing.......i just wondered if there was an easy way to make it work the way i wanted to with out reinventing the wheel! haha...

 

I do not have time at the moment to figure it out, but it would not be difficult to get a tap of the break pedal to interrupt the "on" circuit of the high idle.

I guess I will head back to Radio Shack and pick up the parts I need. I think I am going to use an illuminated switch vs. a switch with a separate LED.

 

After reading all this thread and flagrantly stealing the work that subdieselmech and cspotrun did I took their plan and made one myself today. I took the shopping list to my local radio shack which had everything except for a red led, I subbed an orange one that had the same specs, and I used a smaller box. 4x2x1. Which is a tight squeez but I wanted to mount it inside and that fit the spot I wanted for it better.

Well after a few hours of work I have to say it works as advertised! My only problems were my led for some reason would not allow enough amperage to fire up the relay. I did try reversing the wires but to no avail. It would light up just not work the relay. So I jumped around that, relay now works fine, light not so much though. Also I assumed wrongly the position the pot should be when I fired my truck up and it went to wot then idle and set a check engine light. After clearing the light and setting my pot to the other extreme. It works great!

Still need to mount it and not sure if I want to try to fix or figure out my led problem yet, but I have a working adjustable high idle switch. Thanks to all you guys here.

 

Just tap ("Tee") the LED onto the ground supply wire for the relay and hard wire the other end to a 12V+ Source. Tad more wire but should fix your issue and run the light just fine. Basically take it out of series .

 

What I would really like is to have a green led that lights when the system is off, like when the key is on but the switch is off, and a red led when I have activated the system. Any ideas on accomplishing that?

 

An up date on the high idler system. I figured out how to put another led to have a light on when the key is on but idler system is off and it changes to a different color led when I switch it on. I also figured out that by switching the two db/wht wire and the blk/ylw wire you can change the rotation of your pot.

Now more importantly, it does work for as a fast idler for warm up purposes. It will not work as desgned here for a cruise control. The reason being, for some reason it sets a check engine light whenever you go above 1500 rpms or so for TP circuit out of range.

I have tried to figure out why, I read voltage at the sensor signal wire and worked the accel pedal then switched the box on and and read out the voltage on same wire. The box goes from .30v to about .90 and with it switched off the signal goes from about .36 to 3.77 at wot. So the box is obviously not going out of that range on the high end. The pcm does not seem to care that the signal is that much lower with the box on however.

I also noticed that in operation you have almost a third of the travel of the pot before it starts raising the idle. I thought that is was because I had longer wires by putting the box inside the cab and I also installed an inline connector. So I recorded the voltage at idle with box switched off then switched the box on and dialed it up till voltage was the same then marked that spot on dial. I took the box out and adjusted my 2k resistor untill I had resistance that matched it with dial set to idle stop. I ended up with about 1.56k replaceing the 2k from the plans.

Oddly when I reinstalled the box it still worked exactly the same. It was the same amount of rotation till it matched what the signal voltage is from the truck.

Anyway my findings are that it will definatley work as a idle bump to help warm the cab but as it is designed here it would not work for a poor mans cruise control nor would it be very marketable to sell as I know if I paid any real amount of money for this and it worked as imprecisely as it does I would be dissappointed. That being said however I am grateful for the designing and calculations that Subdielselmech and Cspotrun did here and am satisfied with my results.

 

Do you think that the MIL was set because we are not addressing the Idle Switch leads? Meaning the PCM still thinks the pedal is 0% and then you start to add voltage and once it hits a certain point, it pops the code? Maybe this range was built in for the PTO operations? Just tossing out guesses here. BUT who’s not to say that if we can isolate the APPS from the circuit completely and direct all the function to the POT and relays, why wont it function just as the pedal does with out the codes? Just some thoughts here.....

 

That's exactly why it sets a code. This design does not address the idle switches. It works as Dan wants it to as a cruise control. But with the extended wires I couldn't get WOT. I think the reason is two fold.
1. The addition of the two 1k ohm resistors basically takes up 2k of overhead.
2. The added resistance of adding wire to get the box in the cab.

The 2k of resistance overhead can be thought of like this. You have 10k of varible resistance and 2 k of built in resistance. To get the voltage drop from 5 volts to .5, 12k of resistance is needed. So with the 2k of built in resistance you take away the ability to move from 5 volts to .5. you know have the ability to move from roughly 4.25 volts to .5 volts.
Anyways if the weather holds again for the weekend. I'll get pics up of the box, its innards, and the final underhood install.

 

The idle switch leads are just an on off deal? Correct? SO one could tie in another relay to brake this contact when the high idle is turned on so you have full range of the POT without any MIL's? All you would need is another:

12VDC/10A DPDT Plug-in Relay
Model: 275-218 | Catalog #: 275-218

Right?

 

I agree that it makes sense the code is being set because the pcm still thinks the pedal is at rest or idle. Not sure if the idle verification switches are just on or off though to make a guess as to whether or not they could be tricked with another relay but that is an idea.

I am not sure what You mean, Cspot run though. You obviously have much more electronics knowledge than I, But realizing I was adding resistance by extending my wires and also by adding an inline connector. I adjusted the 2k resistance your plan called for. I first built it with the 2k then plugged it in and read out voltage the pcm was seeing at idle box on and box off. I then checked my resistance when the dial was set to that point and subtracted the difference. Which is why I now have 1.56k of resistor added into the signal wire from my box instead of the original 2k.

So what am I missing or did wrong?

Also were you able to run your engine almost up to wot with yours Cspotrun? I could only get a little higher than 1500 before it kicked its code and pcm took over dropping the rpms back to idle. It would not respond to either the box or the pedal till I restarted the engine. I do have the ability to read codes and it set a tp out of range code. I have cleared it and it does not return unless I go over 1500 or so rpms.