I'm building a 77 Supercab on top of a 99 Superduty Frame, for those interested you can check out my thread "How Small is a Supercab"
I am at the point where I am getting all of the wiring into the truck and married together. I have decided not to use the Superduty brake pedal position switch because of the minimal amount of space between it and the steering column. This truck will have cruise control so I do need to keep the full function of that switch though. I plan to use the original 77 brake switch for lights and then it will either work a relay to switch the PCM trigger from ground to hot with the brakes or have a second DPST push switch. The issue I have is that I cannot find the pinout for this switch.
Looking at the wiring diagrams I have which are for a 2002 it seems that;
Pin 1 Ground
Pin 2 PCM wire
Pin 3 10A Hot
Pin 4 Brake Lights
Pin 5 20A Hot
Looking at the wires poking out from under the dash though 1 and 3 are Hot (Fuse 13 and 15). 2 is green and goes to a join with about 6 wires coming out of it, all cut off when I shrunk the harness (Ground Maybe) one of the others runs into a join with about 4 wires going through the firewall and to what used to be the instrument cluster and I don't remember where the last one went, not through the firewall I remember that. I am very confused. Does anybody have an actual pinout for this? or maybe a wiring diagram for the 99 trucks? the 02 stuff has been pretty good but the wire colours are all wrong and some of the circuits are different.

 

BUMP, Anybody out there have any ideas about this BPP?

 

I'm still trying to figure out what you're asking for? Your combining a 77 onto a 99, and you're trying to use the 99 wiring into the 77? trying to wire 77 into the 99? the wires you're showing are they from the 99 wire harness or part of the 77 wire harness? What is that 4 wire connector originally used for? I mean the 77 is a simple 2 wire momentary switch...

 

Greetings from Tumbleweed1954

 

I am using all of the 99 Engine controls. Because the 99 has cruise control and it is run through the PCM I am also using the 99 wiring for the cruise control. I haven't got room for the 99 Brake pedal switch under the dash so I have to come up with a different solution while still sending the PCM a signal that switches from ground to hot when the brakes are applied. I cannot use the simple momentary switch that is in the 77 for that.
The wires I am showing are the 5 wires that come out of the back of the 99 brake pedal position switch. I need to use those wires to signal the PCM.

 

Nice name, I must admit I was confused when I got a notification saying at first glance that I had responded to it.

 

Install a SPDT 12V relay operated off the stop lamp circuit to make a logic signal switch to replace the missing "proper" switch. Wire it so it energizes when the pedal is pressed and the brake lights come on.

Connect the C terminal of the relay to the signal wire for the PCM (and everything else), the NC terminal to ground, and the NO terminal to a fused ALWAYS HOT circuit.


'99 Super Duty schematic

 

Thank You, The plan is to go with the relay approach to keep it tidy under the dash rather than the second switch on the brake pedal.

For all that are interested, that diagram shows exactly what you need to decipher the 99 Superduty BPP Wiring.

Pins
1 GN/BN 20a Feed
2 GN 12v Brake Signal
3 BL/BK 5a Feed
4 RD/GN PCM Signal Wire
5 PK/ON Ground