brake light cut in and out mysteriously

[Thunderfoot]

If you have no power at the Brake Light Switch but your Hazards and Turn Signals work then you have a open in the power wire to the Brake Light Switch. The power from the fuse box for the brake light is also the same one for the Hazards, it splices off the same line (usually around the Hazard Flasher connection)... Your going to have to trace the wire back and find out where it is opened up at, it will be the Red/Black striped wire.
The power goes from the Brake Light Switch to the Turn Signal Switch and then out to the Brake lights out back.

[quantumleap]

so i figured out that brake lights work off and on..depending on the location of the turn signal lever(center position)... and also still no dome light..bulb and fuse are both good.

[Thunderfoot]

The wire diagram for the dome light http://www.fordification.com/tech/wiring/68-40.jpg wires 54 are the power for it (going to the door switches and light switch) and wires 53 are the output power to the dome light.

[Thipdar]

Dome Light circuit is likely a separate issue (so is radio).

Common areas for brake lights (both R and L): 20 Amp Fuse, Brake Light Switch, Turn Signal Switch, Steering Collumn Electrical Connector, 4-pin electrical connector (wires #977A, 282, 283 & 285) and 4-pin electrical connector (wires # 140A, 282, 283 & 285).

Wire #285 gives power to your tail lights (rear parking lights); if they are working, the two 4-pin connectors are probably ok.

You said you already changed out the Brake Light Switch, so we can assume it's good.

My guess is that you need to swap out your Turn Signal Switch.

This info is based on the wiring diagram for my 1970, but I looked at the diagram for the '67 and it seems to be the same, at least as far as this stuff is concerned.

Good luck with it.

[fordman]

yes the dome and brake light are separate fuses. but behind the fuse box they are fed power by a single wire that splits up to each fuse. the radio has an inline fuse. my guess is it is in the turn signal switch also. the dome light may have a separate problem now. or it could have related back to the single power feed to both fuses. i don't know it has to be looked at and checked.

[quantumleap]

was looking under the dash earrlier and noticed a blue/black stripe and a red tied together with a 90 degree boot connector? not plugged into anything...havent found where it connects to yet..gonna investigate further...the radio is fixed by the way(bad connection at the ignition switch)

[quantumleap]

this is what i found... cant find where it connects

[fordman]

i am going to guess maybe it goes to the instrument cluster. where doe sthe wire lead to under the dahs? doe sit go into the main harness or does it lead elsewhere? i cant find that color combo anywhere that i have looked yet.

[quantumleap]

it goes into the main harness behind the dash..previous owner had it jimmy rigged into aftermarket tack light/trailer brakes

[fordman]

it must be insturment cluster dash lights then or an extra that was never plugged in to begin with on that truck. i have two more harnesses to look at to say for sure that i have never seen that plug. but i know i have.

[quantumleap]

well i know it has power to it cause it used to power and aftermarket tach with just copper wire contact in it

[Thunderfoot]

kinda looks like the power plug for the cigarette lighter. FYI the dome light and cig lighter are on the same circuit...

[fordman]

yeah i looked at all the plugs on all the harnesses i have here and i have not found a plug like that on any of the harnesses i have. the cigartte lighter is usally one wire plug to it for the element and one for the back light. the back light wire color is always solid blue from what i have seen. the element i think is always black i think. soemthign i thought of earlier is that since this truck seems to be a mix of several trucks mayeb the harness came from a 73-79. or maybe a 73-75. i know the 73/74 wirign is pretty much like ours with the fuse box atleast. the 74 diagrams are too big and hard to read from. http://www.fordification.net/tech/wiring.htm

[quantumleap]

kinda looks like the power plug for the cigarette lighter. FYI the dome light and cig lighter are on the same circuit...

maybe a good possibility...i have a deletion plug on the dash...maybe the p.o. deleted the cigarette lighter to get power to the tach?