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Tow Mode Not Possible on PIU

bt1987

Active Member
Joined
June 8, 2018
Messages
56
Reaction score
1
City, State
Columbus, OH
Year, Model & Trim Level
2014 Ford PIU
Hey all, I know that several folks, myself included, have wondered whether Tow/Haul mode can be added to the PIU. I can say with 100% certainty that Tow/Haul mode is unavailable on 2015 and older model PIUs.

On the 2011-2015 Explorers, if the vehicle did not have the center stack switches below the headlight switch, removing the trim panel exposes a wiring harness which plugs into the center stack switches. This enables Tow/Haul mode on even the most basic model Explorers.

On the 2012-2015 PIU, there is no wiring harness behind this trim panel. None of the wiring is pre installed for any of the features that go to the center stack switches, including Tow/Haul mode.

A study of the wiring diagrams for these model year PIUs shows some interesting information. Tow/Haul mode starts at C2280B pin 3, then splits off. One wire runs to the momentary Tow button, and then directly to the PCM, C175T, pin 31. The other wire runs to the Brake Shift Interlock and the Grade Assist button. The output of the Grade Assist momentary button feeds back into the wire to the PCM, C175T, pin 31.

The Low Gear button in the PIU starts at C2280B pin 7, then runs to the Low Gear switch, then from the switch it goes directly to the PCM, C175T, pin 31.

I figured that the vehicle logic system would determine the difference between a momentary 12 volt connection between C2280B pin 3 and the transmission, or C2280B pin 7 and the transmission, as the two are fed by separate fuses. Well, I was wrong. I went and created my own jumper. I plugged a wire into the empty cavity of C2280B pin 3, and then took another wire, and attached it into the backside of the steering column connector which is the output of the Low Gear switch, since the output of either the Tow/Haul or Low Gear switches feeds directly to the same PCM pin. I placed my vehicle in Drive, and touched the two wires together. Each momentary touch from pin 3 also activates Low Gear.

This means that "Low Gear" programming for the PIU is different than Low Gear programming for a retail, floor shift Explorer.

Has anyone else been able to enable Tow/Haul mode? My research indicates it is simply not possible.
 






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