High Idle

[Scarecrow]

Had my truck flashed years ago by Dodge for the high/3 cyl idle, but has never worked. Truck is a 98.5 3500 5spd with Edge EZ, living in northern MN the temps get down to -20 and lower routinely. Replaced the IAT sensor and still nothing, anyone got any ideas what the problem is? 

[Me78569]

Review the TSB it covers what conditions must be met to go into high idle.  

 

 

[Scarecrow]

Okay, so as I read this, the high idle will only work with a automatic?

 

[Me78569]

Per the article

 

Quote

Once enabled, idle speed will slowly ramp up from 800 rpm to 1200 rpm when all of the following conditions are met:

1. Intake Manifold Temperature less than 0°C (32°F) and,
2. Coolant Temp is less than 60°C (140°F) and,
3. The Transmission is in Neutral or Park and,
4. The Service Brake pedal is not depressed and,
5. Throttle = 0% and,
6. Vehicle Speed = 0 mph

 

 

Works with Auto or manual. 

 

Verify all the conditions are met on a sensor level, 

 

IE verify tps reads %0 at idle state

Verify your brake switch sensor is good

Verify your nuetral safety switch is good.

verify your truck reads 0 mph while stopped.

[Tractorman]

2 hours ago, Scarecrow said:

anyone got any ideas what the problem is?

 

Many people don't set park brakes.  If you are one who does not set the park brake, you are likely to have your foot resting on the service brake pedal while you are starting the engine.  That is will probably cancel the high idle feature.

 

I found this out myself accidently.

 

- John

[Scarecrow]

Okay, From the top.

Not sure how to verify tps is at 0%, idles at about 750-800 rpm

No brake lights on or foot on brake when starting

Manual trans, no neutral safety switch

Speedo reads 0

 

Just trying to figure this out, high idle/ 3 cyl idle would be really nice when it's -30

 

 

[Me78569]

you need to read the sensor data using a scan tool. 

 

 

 

The most likely thing is either the APPS reading > %0 at idle or that the dealer did not actually enable it.

 

Edited January 23, 2020 by Me78569

[Scarecrow]

Will I have to unplug the Edge to have it flashed?

[Me78569]

no,

 

But test the above before you take it in again.

[Tractorman]

7 hours ago, Scarecrow said:

Just trying to figure this out, high idle/ 3 cyl idle would be really nice when it's -30

 

Just be prepared mentally if your engine goes to 3 cylinder idle at thirty below zero.  The first time (and only time) that mine went to 3 cylinder idle, I thought the engine threw a rod bearing from the racket it made.  And that was at 18 degrees above zero.

 

I make sure that I step on the brake pedal when I start the engine in cold weather.  I use the exhaust brake for faster engine warmup.  Much quieter.

 

- John

[Royal Squire]

Moparmans high idle switch is very handy. I use it often. 

[wil440]

Boy am I glad we don't get 30 below here in the uk, only been just below zero maybe 5 or 6 times here this winter, one benefit of living on a small island right in the path of the gulf stream, but it can rain for England ?

[IBMobile]

2 hours ago, wil440 said:

only been just below zero maybe 5 or 6 times here this winter,

Is that zero celsius or Fahrenheit?

[wil440]

1 hour ago, IBMobile said:

Is that zero celsius or Fahrenheit?

Celsius. I haven't used 1/2 a can of deicer yet ☺  but as we are surrounded by water our coldest time is feb and march, takes longer for the sea to warm so the boffins say

[Scarecrow]

I was thinking about Mike's switch for a while now, but want to check  my tps and flash to be sure that's not the problem. As I understand Mike's switch to work the high idle has to be enable. The MPG feature would be great as winters up here tend to be long and cold. The real fun is to have a cold snap in Oct, and get caught with B20 in the tanks!