Question 08 High Idle Mod

I just completed the high idle mod to my F-350. Can the truck be reprogramed to not to have the parking brake engaged to enable the High Idle Mod? Also can the RPM be changed from 900 RPM to 1200RPM? I used the BCPSW input. I did not want to use the PTO input as to keep the torque conveter from locking up. I will only be using it for the cold weather. Thanks!

im not at all familiar with it, but you may be able to put a switchable bypass on the park brake switch to supply a fake "brake on" signal.

can you link us on how you did this? i would be interested in this to.

It is easy!

I hooked upfitter switch #3 blunt cut wire (VT/GN) to the BCP SW blunt cut wire to the PCM (VT/BN). These wires are under the dash and to the left of the stering wheel. The attachment should help you locate them. I used the BCP Sw input versus the PTO input as to not have the torque converter locked up during the high idle. Just set the parking brake and flip the switch and the engine should go to 900 RPM. Maybe someone can help with a program change to eliminate the parking brake and also raise the RPM's a bit more. Good Luck!

When you hooked up to the battery charge wire it will change the idle depending on the load on the battery, obviousely higher load means higher rpm, and lower idle for smaller load on the charging system. i've seen the rpms from 900-1500. usually right after a cold start or when the a/c is on its around 1200, saw 1500 on a cold start this am until the batteries were sufficient the idle dropped down to around 1200. As for eliminating the park brake i'm not sure how to do that.

I just did that to mine. Your right it was very simple. When I first flipped the switch the idle went up to 1200rpm for about a minute then it dropped down to 900 rpm. I wish I would have done this last year. Thanks again!

I guess my batteries were fully charged when I tested the mod. I guess that 900 rpm is enough to keep the engine from wet stacking and keep the turbo's spinning fast enough. Thanks!

I just completed this mod. Really easy with the pics, thanks Jeffro.

Just for clarification?

I'm probably gonna sound like the newb that I am as far as diesels go... but what exactly are you guys using this high-idle mod for? Is it for accessory power and/or for those cold morning starts?

If it's for the cold morning starts, that leads me to another question or two: I was under the impression that a prolonged idle was bad for the 08's thanks to the evil DPF? If you're not supposed to let it idle- wouldn't this mod cause even more problems? Also, how can you defrost a completely frozen truck in the morning if you're not supposed to let it run long enough to get rid of the ice? This issue has always bothered me about the 08's.

Didn't mean to try and thread-jack, just wanted to ask a few questions before trying this mod myself. By the way, GREAT info and illustrations!!

You are right. Excessive idling is bad for it. When the truck is first started, it will idle up after 130 seconds when it is cold. The high idle mod is used for really cold weather to help keep the engine warm and to burn the fuel better while idling. Sometimes you have to idle it to keep warm. It can be handy for jump starting other vehicles. In Mississippi you probably do not have much problems with cold weather.