2wd Low on F150...

[Musclford]

Anyone do this on an F150?

Doesn't sound like it's as easy as just clipping the wire like the Super Duty's

Naturally this guy went a bit overboard, but with you having to ground the wire instead of opening it.. perhaps it's the best way.....
Musclford

From the F150 Forums...


"Low Range 2WD Mod.

What it really does is allow me to disconnect the front hubs using a switch on the dash. Now I can use "Low Range 2WD" to move my camper around my yard and on steep campsites even when I'm on a hard surface road, with no drivetrain bind. I may also use it on steep rocky trails where I want the low range speed and control but don't need the front wheels to be pulling or the drivetrain to be binding.

Here's what I did:

First I put a switch in the dash with power feed from the cigarette lighter wire (because it was easy). Power from the switch runs through a wire to the engine compartment. I installed a waterproof 5-pin relay next to the existing "4X4 Center Axle Disconnect Solenoid" on the firewall near the battery. The "4X4 Center Axle Disconnect Solenoid" is really a hub-control solenoid-operated vacuum switch, which I'll call the 4X4 Relay (since its shorter!). I then cut the red wire that leads to the 4X4 Relay, and wired in my new relay as follows:

Pin 30 - to red wire running to existing 4X4 Relay
Pin 87A (Normally Closed connection) - to red wire running into wiring harness (runs to the PCM)
Pin 87 (Normally Open connection) - to local ground on the firewall
Pin 85 - hot wire from my new switch
Pin 86 - to local ground on firewall

When my switch is ON, the red wire from the 4X4 Relay is grounded to the body, and the wire to the PCM is disconnected. This activates the 4X4 Relay and disconnects the hubs. When my switch is ON in 4WD HI the dash indicator does not come on for some reason, but the front driveshaft is engaged although the hubs are unlocked, so I don't have 4X4. When my switch is ON in 4WD LO the dash indicator does come on, low range is engaged, and the front driveshaft is engaged, but the hubs are unlocked, which gives me 2WD LO.

When my switch is OFF, the red wire from the 4X4 Relay is connected to the red wire to the wiring harness, as before, and the PCM can ground the connection to unlock the hubs or unground it to engage them, as normal. So 4WD HI and 4WD LO both work exactly as before when my switch is OFF.

One note - I didn't try it, but I think a "quick and dirty" way to do this same mod would be to use a "quik-tap" wire tap on the red wire and run a lead to the battery ground post, either with a switch or just clamping it on when desired. I wanted the switch inside the cab, and I wanted the PCM to be disconnected from the circuit when I was activating the 4X4 Relay, just to be sure I couldn't hurt the PCM somehow, so I went with the fancy complicated method."