04.5-05 LLY Performance Discussion of Chevy and GMC Trucks with LLY Duramax Turbo Diesel Engines Related To Performance And Longevity

High Idle

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  #1  
Old 02-01-2009, 10:59 AM
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Default High Idle

Anyone install a high idle kit on their LLY. I am looking to make my own based on the http://www.gmupfitter.com/publicat/bull/bull71.pdf publication and just wondering if anyone has done this. If so, looking for some help.

I am trying to make the mod and hide it. I am also working on a hidden kit that will allow to turn on the fog lights (switched of course for the option) when the low beams are on. I have already modded the low beams so that they come on when the high's are on, but will be upgrading this to a switched setup.

I did the low/high combo mod when the truck was 6 months old (the fog lights still go off). You should have heard the tech who worked on my truck at the steeler. He could not figure out what the f&*^ was in the fuse block. Just a diode and a couple of modded relays did the trick. If you want pictures, let me know and I will post. I will also post the completed switched options when finished if anyone wants them.
 
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Old 02-01-2009, 12:42 PM
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the diodes in the fuse box is pretty nice, some pics would be nice. i cant do that with my truck, it has a different electrical system in it
 
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Old 02-01-2009, 12:48 PM
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you can do it like this..

High Idle Speed Enable and Disable


To enable or disable the high idle system perform the following procedure:

  • Turn the ignition ON with the engine OFF.
  • Depress the accelerator pedal to the floor and hold down.
  • While the accelerator pedal is depressed, depress the brake pedal 3 times in less than 8 seconds.
  • Release the accelerator pedal.
  • Start the engine.
When the procedure is followed the engine idle speed will slowly increased to the calibrated high idle speed. This is 1200 RPM for Light duty, and 1500 RPM for medium duty trucks.

The idle speed will return to normal if any of the following conditions occur:

  • There is brake, clutch, or throttle input from the driver.
  • The automatic transmission is shifted out of Park or Neutral.
  • The air temperature is more than 0 °C (32 °F).
  • The engine coolant temperature (ECT) is more than 68 °C (154 °F) The vehicle speed exceeds 0 MPH (0 km/h).
The high idle system will reactivate automatically when the following conditions occur:

  • The engine has been idling for more than 30 seconds.
  • The transmission is placed in Park or Neutral.
  • The vehicle speed is 0 MPH (0 km/h).
  • The ambient air temperature is less than 0 °C (32 °F).
  • The ECT is less than 68 °C (154 °F)
  • The brake, clutch and throttle pedals are not depressed.

Elevated Idle Description for LLY Duramax
 
  #4  
Old 02-01-2009, 01:12 PM
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Default Pic of Diode installed

Here is a picture of the diode and the result. As long as the headlight system runs off of relay's, you can do the same thing. What this does, is to activate the low beam relay off the signal for the high beam. This way, there are no extra relay's, wires, fuses, and connections to deal with. Keeps it looking clean under the hood.

As for the High Idle. I am looking for the PTO High Idle. Anyone done that mod yet without using the GM part????
 
Attached Thumbnails High Idle-p2010849.jpg   High Idle-p2010850.jpg  
  #5  
Old 02-01-2009, 01:25 PM
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damn that a big ol diode, i only used the 4001's and jumped the 85 terminals
 
  #6  
Old 02-01-2009, 08:56 PM
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That is a 6A diode that I had. I am going to change it with a smaller one when I redo my wiring.

Right now I am trying to get the PTO High idle to work without installing the GM switch. I would like to keep the PTO high idle hidden.
 
  #7  
Old 02-04-2009, 07:37 PM
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The LLY's have High Idle programable in the DIC.
 
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Old 02-04-2009, 09:46 PM
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I am going for the PTO high idle not the cold weather high idle.

I found the pins at the local steeler. He told me they are $5 each (what a load of crap) as there is no charge code for the pins. I will try to get it up and running this weekend, but I only have a limited time as I have to travel for work on Sunday.
 
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