One question. What is that for?

 

Mine high idles in really cold weather. Our mornings have been in the high 20s. Once I start my truck and let it idle for a couple of minutes, the idle RPM will go up to about 1200 rpms until I touch the brake pedal or the skinny pedal. So to answer your question, it helps warm up the engine in super cold weather.

 

accelerates engine warmup, and on the newer 6.7L trucks it helps prevent the DPF from getting plugged up from excessive idling.

2nd gen 24v's like mine have two high idle modes. 6-cyl high idle, and 3-cyl high idle.

6-cyl high idle comes in automatically when IAT sensor readings are below 32*F
3-cyl high idle comes in automatically when IAT sensor readings are below 15*F


both work similar.. both require coolant temp to be under 125*F to start high idle and both shut off automatically at over 170*F coolant temp.

both idle normal for 1 minute then ramp up rpm to 1200rpm.

6-cyl mode holds 1200rpm. 3-cyl mode revs to 1200rpm and then cuts out the front 3 cylinders and runs on only the back 3 cylinders and maintains 1200rpm which causes EGTs to more than double because the engine created an artificial load on itself. warms up twice as fast.

only the 24v VP44 trucks have the 3-cyl high idle option. common rails do NOT have this option.

also 2nd gen 24v's must have the high idle option enabled in the ECU as Dodge has it disabled from the factory. must either have a dealer enable it by flashing the ECM, or use a smarty S-03 programmer to enable it.

 

Well said jigabop!

 

Mine is deleted so I just use it to warm it up.

 

Hi Im new to the diesel thing, I have a 2000 3500 Dually and was wondering how do I determin if I have a common rail or a VP44....and I guess my second question would be what is the diffrence
thanks

 

common rails started in 2003.
yours is a VP44 pump.

that's the simple answer.