Question About D-max

Sir Dan · July 15, 2007

So may dad just got a 2007.5 Silverado 2500 LTZ D-Max. The dealer told my dad not to let the engine idle for more than 20 minutes or he'd have to bring the truck in for some kind of computer reset or something. What's this about? Not being able to idle this thing especially in the winter time is almost unacceptable!

s-ten · July 16, 2007

Never heard of that before, but you are right about it being unacceptable to not be able to idle a diesel in the winter. Sounds to me either the dealer did not know what they were talking about or your dad misunderstood them.

I am interested in finding out more about this.

dwweber · July 16, 2007

I thought the '07 D-max had an option for a 'Fast Idle'. I remember seeing a setting for it when I was looking at the '07s. The dealer told me it was for warming the truck up during the winter or when using a PTO/high electrical loads.

Check the owners manual, if it doesn't give the same warning... then the dealer was either wrong or misquoted.

Sir Dan · July 16, 2007

No fast idle option. I checked that out in the manual right away. My buddy has an '05 D-max and he does have the fast idle option. The more I think about it, the dealer has got to be wrong on this or Dad misunderstood something. Thanks for the input on this guys!

superbee · July 16, 2007

I have fast Idle on my 06. I'm surprised to hear there isn't one on the new ones. That stinks. The extended idling issue may have something to do with the Particulate filter on the exhaust. I'm just guessing. Dealers are notorious for being wrong.

GMTRUCKTECH · July 17, 2007

READ THIS

Manual High Idle System Description

High Idle System

The diesel engine has a high idle system to improve the warm-up time of the engine in cold weather conditions. This system allows the engine control module (ECM) to increase the idle speed above the normal calibrated value. The ECM increases the idle speed using the following adjustments:

• The fuel injection timing is changed.

• The fuel injection quantity is changed.

• The turbocharger vane position is commanded closed. The vane position will be farther closed than any other normal operating condition.

The instrument panel will indicate the high idle system is active one of two ways:

• The driver information center (DIC) will indicate an active high idle system on light duty trucks.

• An indicator lamp will flash on medium duty trucks.

• The manual high idle feature comes enabled from the factory. The Elevated Idle function in the scan tool will disable or enable this feature. If the engine does not increase to the calibrated high idle speed after the procedure is performed, use the scan tool to verify the Elevated Idle speed feature is enabled.

High Idle Speed Enable and Disable

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

<LI type=1>Turn the ignition ON, with the engine OFF. <LI type=1>Depress the accelerator pedal to the floor and hold down. <LI type=1>While the accelerator pedal is depressed, depress the brake pedal 3 times in less than 8 seconds. <LI type=1>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 1,200 RPM for light duty, and 1,500 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 7°C (45°F).

• The engine coolant temperature (ECT) is more than 68°C (154°F).

• The vehicle speed exceeds 0 km/h (0 mph).

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 km/h (0 mph).

• The ambient air temperature is less than 3°C (37°F).

• The ECT is less than 68°C (154°F).

• The brake, clutch and throttle pedals are not depressed.

Sir Dan · July 18, 2007

Thanks alot for this info! It's disappointing that the dealer didn't go over all this with Dad especially knowing it was his first oil burner. Still have to check about the limiting the idle time to under 20 minutes thing....

Thanks again!

JunkTruck · August 6, 2007

So may dad just got a 2007.5 Silverado 2500 LTZ D-Max. The dealer told my dad not to let the engine idle for more than 20 minutes or he'd have to bring the truck in for some kind of computer reset or something. What's this about? Not being able to idle this thing especially in the winter time is almost unacceptable!

It has to do with the DPF. The filter will clog and a manual regeneration will have to done by the dealer. Read the owners manual. It will tell you all about the emmisions stuff.

Bobslob · August 6, 2007

Yep it's the DPF, stupid tree huggers

SoylentGreen · September 21, 2007

So may dad just got a 2007.5 Silverado 2500 LTZ D-Max. The dealer told my dad not to let the engine idle for more than 20 minutes or he'd have to bring the truck in for some kind of computer reset or something. What's this about? Not being able to idle this thing especially in the winter time is almost unacceptable!

You might be getting confused with the remote start run times. The remote start will run for 10 minutes and then turn off, but you can get another 10 minutes by pressing the button again before the first 10 minutes is up. But the book say's it will only idle for a total of 20 minutes if you do this. Then you would have to start it by the key.