Center Differential Lock Pin 7 Mod
Dan Busey and Spencer Bybee
DO NOT DO THIS MODIFICATION IF YOU DO NOT HAVE A CENTER DIFFERENTIAL LOCK SWITCH INSTALLED
Remove the dead pedal and the left front sill plate.
In the left kick panel you will find a Silver metal box. That is the ABS ECU.
Remove it, and behind you will find a black plastic relay about the size of a cigarette pack. It says "transmission control relay" on it. That's what you are after. The EWD calls it the "center diff lock relay", same thing.
Unplug the harness from it and take a terminal pick and remove the black wire with blue tracer from pin#7.
Insulate the bare terminal to suit and then put everything else back where you found it.
If you have the low 4 position switch at the transfer case unplugged, crawl under there and reconnect that as well.
What you have just accomplished is you have interrupted the signal from the transfer case that tells the lock ECU that you went to low range but you are still sending a signal to the transmission ECU telling it that you ARE in low range. Therefore the transmission will shift in the correct low range pattern. In addition you now have true manual control over center diff locking. It only locks when you tell it to without regard to transfer range selection.