I have a 1987 f350 6.9l in need of some help. And after my last problem I had I found out people on here give great advice so here are my current list of problems:
tach is broke
speedometer is 10 off
cruise control is broke
no horn
fuel gauges wobble alllloottt
oil pressure gauge wobbles with the throttle
glow plugs are wired seperately from the ignition

also my truck only has 83k miles on it (and i know it has not rolled over because I know all its past owners) and when I start it up it knocks for the first twenty seconds or so and then is fine and when the hood is up while its knocking some smoke blows out of the back of the motor (my valve cover gaskets leak a little oil) so im guessing its coming out of there..i have a hard time believing something would be wrong with the motor if its barely broke in..
so here is what we are dealing with:


and here is the wiring im dealing with that i believe could be the cause of alot of these problems: in this picture you can see the red and yellow wire escaping out the back...these are what lead to my glow plug push button

and here are a few things that arent connected to anything...this is right in the back of the engine bay on the drivers side where all the wires lead into the cab

the three wires in my hand here are the same ones from the picture above

and this one is over on the other side near the voltage regulator..looks like it should be going somewhere..but im not sure lol

and this one is right next to the radiator in the front...i believe this could be the cuplrit to my horn problem..but i was under the impression a horn took 2 wires...

and then this im just guessing is involved with the glow plugs not being hooked up right

 

No offense, but it looks like the PO's had the electrical skills of a caveman...
Some of the wiring, the pic showing the heater core area, possibly goes to the acculator or somewhere in that general....Best way to source the wires, it to extend the wires/plug out fully and look for some sort of receptacle....

Best of luck man....Beautiful truck btw....You may even want to just redo the whole wiring harness....

-Wes

 

Cleaning up the wires carefully so you can know for certain what colors they are (assuming they don't appear to have been cut and replaced) will help you match them to a good wiring diagram.

 

ok the cut and spliced up wiring is mainly for the glow plugs...but i wont worry about that right now because my glow plugs at least work, id rather focus on getting things like my fuel gauges and my tach to work properly...

 

and for the cruise control and horn..ive been reading about something called a clock spring? not sure what thats all about, but its come up several times