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Elevated idle not working

15K views 15 replies 8 participants last post by  Matt G 
#1 ·
I turned on the elevated idle a few weeks ago. My trucks been sitting for a full day and it’s 29 degrees out. Went outside and started the truck. Coolant temp was 39 degrees and outside temp 29 but no high idle kicked on. Am I missing something ? 2011 LML
 
#2 ·
What do you mean "turned on the elevated idle?
Normally you don't have to do anything- if its cold enough it will ramp up the idle speed after a small period of time.
Later in the post you mentioned "high idle"". Two different things- high idle is an option, elevated idle is on all dmax's except maybe the first ones.
 
#3 ·
Elevated idle can be turned on & off. High Idle is different than elevated idle. Revs up to a higher RPM and initiated by pressing the parking brake and the cruise control buttons (at least on my yr model truck). How long did you let the truck idle for? I have my elevated idle tuned on my truck and it has yet to turn on this year as well. Most of the time its cranked in the garage but a few times at work it hasn't come one. Been waiting for it to get colder and park it outside for the night to see if it works.
 
#4 ·
mines kicked on at least a half dozen times already.
 
#6 · (Edited)
GM's instructions really added to the confusion by the way they describe the warm-up feature:

Cut and paste from 2011 manual:

Elevated Idle

The engine has a cold temperature high idle feature which elevates the engine idle speed from base idle to 1050 rpm for pickup models or 1200 rpm for van models when outside temperatures are below 0°C (32°F), and the engine coolant
temperature is below 65°C (150°F).

This feature enhances heater performance by raising the engine coolant temperature faster.

This feature can be turned on or off using the DIC buttons. If the vehicle is not equipped with DIC buttons, do the following to turn this feature on or off:
1. Turn the ignition to ON/RUN, with the vehicle off.
2. Press the accelerator pedal to the floor and hold while quickly pressing the brake pedal three times in less than eight seconds.
3. Release the accelerator pedal and start the engine.

When the engine is started, it will slowly ramp up to the high idle speed after a delay of a few seconds up to approximately
two minutes.

For this method to work properly there must be no throttle or brake pedal faults.



The engine idle speed will return to normal once the following conditions are met:
. Once engine coolant temperature reaches 65°C (150°F).
. Air intake temperature reaches 0°C (32°F).

The high idle speed will be temporarily interrupted and the engine speed will return to normal if any of the following conditions occur:
. The brake pedal is applied.
. The accelerator pedal is pressed.
. The transmission is shifted out of P (Park) or N (Neutral).
. Vehicle speed is detected.

Once these inputs are removed, the engine idle speed will slowly ramp back up to high idle after the normal delay, if the conditions for engine coolant temperature and air intake temperature are still met.



There are separate instructions for the optional Fast/High Idle feature that is operated with the cruise buttons.
 
#8 ·
I activated the elevated idle as stated above by pressing the gas pedal and hitting the brake 3 times and it came up in my DIC that it was activated. The other morning it was 29* and the engine was ice cold. I started the truck and it idled for 10 min at 7-800 rpm until I drove off.
 
#12 ·
Once it's been enabled, you shouldn't ever need to 'turn it on' again. When conditions are met it will turn on -- makes it so if remote starting it's not necessary to go out to truck to have 'elevated idle operate'.

Elevated idle should be about 1050 rpm.

There are a bunch of reasons the ecm will raise the idle speed to other levels - charging, hvac etc.

If the necessary conditions are not met, it does nothing, so no reason to turn it off. (at least I've never heard one).
 
#10 ·
Probably going to have to take it to the dealer for help with this. I suspect the ecm will have to be looked at
 
#11 ·
Vermont here, my elevated idle was working great until recently. Although it would shut off at 120° rather than the mentioned 150°. Around the time the elevated idle stopped working, I noticed the oil pressure sender is pegged at 120lbs. Havent gotten the new one in yet, so idk if thats the culprit to elevated idle not working... but I suspect so.
 
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