Has anyone ever tried to wire up one of the upfitter switches as an ignition switch/relay.? I have a 2006 F-250 - I would like to use one of the switches as an ignition 'kill switch'. A while back my truck was stolen, I have since installed an alarm system and looked at a system by Ravelco (anti-theft key pin system, supposedly the best out there) but before I went and spent the $$ for the system I figured I would see if I could create a lockout switch for my ignition.

I assumed I would be able to run one of the ignition relay wires through one of the upfitter switches. When I park my truck set all the switches to off so in order to start you would have to turn on that switch. I know not theft-proof, but hopefully it would fool the would-be thief long enough for alarm to go off, wake me up and chamber a round in my .45

Is this is possible?? Thanks for the feedback!!

 

The upfitter switches are only hot in the ACC and RUN positions. They are not hot in the OFF or START positions...

you would have to change the power feed to something that is always hot.

 

Since I can't draw a schematic on here, I'll do my best to illustrate, and please pardon my lack of technical knowledge!

In from starter relay >> key/ignition >> starter coil. Turn key, starts truck.

In from starter relay >> upfitter switch >> key/ignition >> starter coil. Turn key with switch off = nothing. Turn key with upfitter switch in 'on' position, starts truck.

Essentially trying to create an in-line start switch using one of the upfitters. Maybe just makes more sense to put a little switch in-line under the dash/steering column somewhere as a theft deterrent.?

 

well power or not they are still just switches so it is just making or braking a contact use it that way and not supplying power to the circuit would work .. but a hidden toggle is better imho
EDIT I was typing while you were posting .. just to clarify

 

the upfitter switches control relays, power doesn't run through them.

if your key is in START, the upfitter loses power, and the relay will open.

This means that if you connect your starter solenoid circuit through the upfitter relay, you will have no power to the starter solenoid when the key is in the START position.

to do this, you will have to do some major rewiring of the built in circuitry.

 

I wouldn't think it would be that major to intercept the switch input output and bypass the fuse box
but it really isn't worth the effort for this application IMHO plus you loose a good powered switch and fuse

however the OP's idea on how to do it after it is powered up would work I ,, but I would just go hidden toggle or keyed switch myself

just don't kill the fuel pump and still let it crank

 

The switch simply grounds a logical I/O pin on the PCM. It is not designed for any load.

 

Well that explains your position
and disproves mine ! interesting that their is a PCM in the remote fuse box ?

thanks I figured they would just be normal spst or dpdt toggles

 

If you were going to put in a hidden toggle switch, what wire would cut so their wouldn't be any problems?

 

There is only the one PCM... It is the center for all of the logic on these pickups. When you turn the headlight switch, it sends a signal to a certain input pin on the PCM. That signal tells the PCM which position the switch is in, and which lights to turn on. The PCM uses an output pin to energize a relay and turn the desired lights on.

Same with the windshield wipers, the Air Conditioner, Cruise Control...everything. There isn't a single electrical component that the driver actually controls anymore. Everything is controlled by the PCM.

 

I thought you were trying to say the uppfiterswitches were tied to the pcm
and since it is a standalone system I was curious about your pcm comment

but then it dawned on me maybe the o8 is different
mine has it's own fuse and relay box under the glove box

 

All you have to do to disable the starter, or anything else, is to interupt the wire that triggers the relay or provides power directly to the device. It doesn't matter if the signal comes from the fuse box, the battery, or the PCM. The trick is to hide/disguise your wire so that it is not easily detectable.

 

disable the starter and a separate disable for the fuel. That is what you want to do.

 

You're giving way to much credit to the PCM. The PCM controls the engine and transmission. It accepts a lot of inputs and has a lot of outputs, but no where near all of the ones you've described. Cruise Control, yes on diesels and newer gas engines with electronic throttle control. A/C to some extent. Wipers, headlights and other stuff, no.

Other modules do a lot of other things. Depending on the year, the GEM, HEC, 4WD Control, ABS, VSM, SJB, etc, etc. They're all connected by one or more data busses, so they work together. But they are separate modules.

These are the wiring pinouts and circuit descriptions for the three connectors to the PCM. They'll give you a pretty good idea of what it does and doesn't do.

 

Only three images per post.

BTW, these are for a 2004 Diesel. Gas engines and different years are going to be somewhat different.