Upfitter Switches on a Ford 6.0L

Posted by ID Speed on 2023 Jan 24th

Upfitter Switches on a Ford 6.0L

2005-2007 Ford Super Duty Upfitter Switches:

The Ford Upfitter Switches are optional instrument panel mount switches (Option Code 66S) (see

Photo 1) that control passenger side mounted relays. These relays power four blunt cut wires that

can be found beneath the steering column and behind the passenger compartment fuse panel

also called the Central Junction Box (CJB). The wires are part of the harness connected to the “K”

connector (C270K) on the back of the CJB (see Attachment II & III). The four wires are as follows

(see Photo 3):

Switches Circuit Color Fuse
Aux 1 1936 Orange/Light Green 30 Amp
Aux 2 1933 Orange 30 Amp
Aux 3 1934 Orange/Yellow 10 Amp
Aux 4 1935 Orange/Light Blue 10 Amp

To find the wires:

1. Remove the fuse panel trim cover below the steering column.

2. Remove the four fasteners holding the CJB.

3. Lower the CJB without disconnecting any connectors.

4. Locate connector “K” (see Attachment II & III) on the back of the CJB and the harness

connected to it.

5. Locate the four blunt cut wires with shrink wrap on the harness connected to the “K” connector

(See Photo

Operating Procedure:

The Upfitter Switches are operational when the ignition key is in the run position (see Attachment

I). The Upfitter Switches cannot be utilized in any other operational mode. The power to the

switches is relay controlled and was designed to operate in the “run” mode to reduce the

possibility of draining the battery(ies).

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