This is my first attempt at a DIY write up so bear with me.
There is a good write up on this on Kennedy Diesel's page (Kennedy Diesel
) that involves running the PTO enable to a toggle switch, another method is to run the wire from the ECM in to the brake switch at hook it up to the green and white wire on the brake switch. My write up does the same thing as running the wire to the brake switch because it ties into the same circuit, but you only have to run the wire from the ECM to the underhood fuse block.
The high idle is achieved through a PTO enable circuit inside the ECM. When hooked to a 12v source, the high idle can be controlled from the cruise control switch. Turning the switch to "standby" will bump the idle to 850rpm. Pushing the "set" button will take the idle to 1250rpm, and hitting the "resume" function will take the idle to 1700rpm. I hooked my PTO enable to the "A/T Shift Lock Control Switch Supply Voltage" circuit that runs from the B/U lamp fuse in the underhood fuseblock to the stop lamp switch. Hooking the PTO enable to this circuit works for the high idle because it takes away the 12v source when the brake pedal is applied and the truck is in gear. You will need :
- About 3 feet of 20 - 22 gauge wire
- LB7 ECM terminal part # 12084912 (can get them at dealership parts department)
- Terminal crimpers
- 10mm socket
- 7mm socket
- Various sized hook tools and flathead screwdrivers
- Small hook tool or equivalent tool to poke through rubber gasket at ECM connector
- Wire strippers and crimpers
- Electrical tape
- Heat shrink butt connector
- Heat source to shrink the heat shrink Step one :
Disconnect both batteries to avoid smoking any modules. Step two :
Disconnect the TCM by removing the two 10mm bolts that hold the cover to the radiator support. Disconnect the connectors fromt the TCM and set it out of the way. Step three :
Remove the ECM cover and remove the ECM from the mounting bracket (see pic). Next, unbolt both connectors from the ECM. Remove ECM and set it aside. Pull blue connector up towards you to make room to work (blue connector has blue covers on terminals and is the inside connector on the ECM, closest to the power steering pump). Step four :
Remove the wire cover on the outside of the connector to access the back of the connector. Step five :
Using terminal crimpers, crimp the ECM terminal to the end of your wire. Step six :
Puncture the yellow rubber gasket in the back of the ECM connector at terminal # 71 (terminal 71 is the PTO enable pin in the ECM) using a small pick tool, safety pin, needle. Take the terminal and wire that you crimped in the last step and insert it into the back of the ECM connector(you should be able to feel it "click" into place in the connector). Look through the blue terminal protector to make sure the terminal went in all the way. Step seven :
Cut through the tape that holds the wire loom onto the harness and route the wire towards the underhood fuse block. Step eight :
remove the underhood fuse block cover. Look for a looped green and black wire in the harness that comes off of the fuse block
Cut the gr/bl wire at the top of the loop and strip both ends.
Strip the end of the wire that you ran from the ECM. Take one side of the wire from the fuseblock and twist the stripped end together with the wire you ran from the ECM. Take the butt connector and put the wire from the fuseblock twisted with the ECM wire, put it into one side and crimp the butt connector. Put the other side of the gr/bl wire in the other side of the butt connector and crimp it down.
Use a heat gun or butane torch to seal the butt connector with the heat shrink tubing. Go back through and tape up the wire loom that you ran the wire through for a clean look. Step nine :
Reinstall the ECM, TCM and all covers that were taken off. Reconnect the batteries. Start the truck and turn the cruise control to standby, the idle should bump up to around 850rpm. Push the set button at the end of the turn signal switch and the idle should jump to around 1250rpm. Slide the cruise switch to resume and the idle should go to about 1700rpm.
This is a pretty nice mod and is great for cold weather to get the truck up to operating temperature faster. It shouldnt take more than 45 minutes to do start to finish.
Here is a video i took working the high idle through all the settings
If I missed anything or anyone needs more info on how to do this please let me know and I will add it. '03-'04 LB7's :
The same ECM terminal is used along with the same circuit, but the circuit for the shift lock controls comes out of a different terminal in the underhood fuseblock. The wire is the same color (green/black) as the '01-'02's but comes from terminal A8 in connector 1 of the fuseblock and gets its power from the 10A BTSI fuse.