Brake Light/Flasher/Inst Panel light problems

[Wotan]

Okay... hoping somebody can give me some idea of where to start troubleshooting. Here's the situation:

1969 F350. All my lights work... but with a few glitches.

Glitch #1: When the brake lights come on, so do the dash lights.

Glitch #2: The left turn signal operates perfectly normally. I can hear the flasher behind the dash clicking. The right turn signal operates, but there are TWO clicking sounds, and the flashing bleeds through to the instrument panel and the cabin top running lights. (The instrument panel lights and the cabin top running lights flash as well as the turn signal lights).

I have replaced all the fuses, I replaced the brake light switch, and I have replaced one flasher behind the instrument panel. No change.
Hearing double clicking sounds when operating the right signal makes me think it may be somehow tied in with a second flasher, but I cannot locate a second flasher - but the wiring diagram says there are supposed to be two.

So... anybody know where the second flasher is located on a 69? The one that I found was behind the dash, slightly to the right of the steering column.

And can anybody recommend a spot to start trouble shooting?

Thanks!
Andy

1969 Ford F350 - "Wotan"

[HurleyInt824]

did u pull out the column.. i had one by the column and one bolted to the back of the panel.

i had the same problem but with no blinkers... i replaced the switch in the column... and fixed the problem of the brake lights.

[fordman]

the second flasher isnt your problem its in your wiring feeding back through some how. the second flasher is on the back of the instrument cluster on the left side of the column way up in there. it easier to pull the cluster to get at it.

what was the last repair you made? was it under the dash with the column or other similar wiring?

[FORDification]

Has anyone messed with the taillight wiring, for example to splice in a trailer hook-up? With an F350, I'd be willing to bet it has....and that it might be a good place to double-check those connections.

[theogre5150]

I had a similar problem with mine going haywire. I checked where the wiring harness plugged into the cluster and noticed that a couple of the contacts to the circuit board were pushed over and were not making contact with the harness. I carefully moved them back, plugged the harness back in and it worked.

[Wotan]

Update:
I've narrowed a few things down, so I know several things that it's *not*.
However, I still don't know what is causing the problem.

Here's a question - On the passenger side, on the cabin wall forward of the passenger's door, are two small metal electrical "mystery boxes". The 14398 assembly appears to tie into them, but I can't find them on the wiring diagrams anywhere.

The smaller box is roughly 1/2" by 1/2", and has two medium gauge wires (both black with white stripe) attached to it with round terminals and nuts. Both leads are hot when the key is on.

The larger box is a rectangle about 2" wide and 1" tall, and has three spade terminals on top, with three wires attached. All appear to be black with white stripe again, and of medium gauge. All of these wires go up and forward, through a grommet on the firewall, and along the right side of the engine compartment in what I'm *thinking* is the 14398 assembly.

When I turn the right hand turn signal on, the larger box "clicks" like a flasher. But I don't *think* it's a flasher, because I have two OTHER flashers wired in right where the wiring diagram says they are supposed to be. And it does NOT click when I turn the left turn signal on.

Anybody got any ideas?

[basketcase0302]

Wotan,

How about this?
http://www.fordification.com/images/sch ... arkers.jpg

Basketcase

[rjewkes]

sounds like the relay for the cab markers wich maybe the smaller box might have quite and someone replaced it with an aftermarket box but wired in the turn signal wire to get it working by mistake.

perhaps they had the key on with the right flasher going and used it for the power.

when you use the brakes does any outside light come on besides the brakes?

they could have also decided(i have thought the same before) how cool if the outer two cab lights worked with the turns.

[Wotan]

Ahhh... yep. The smaller is the marker light circuit breaker, and the larger is the marker light relay. I was looking at the exterior lighting diagram, and didn't think to look on the marker light diagram.

One more puzzle solved...

I'll check the function of that relay - perhaps there is something going on with it. (shrug)

[Wotan]

I'm all fixed. Turns out I had several problems going on.

1) The marker light relay was bad. Replaced it.

2) fuse clips for the 14v tail light fuse were corroded and not making good contact. Cleaned em up.

3) Somebody had really butchered the rear taillight/brake/turn signal wiring harness when they attempted to wire the truck for a trailer.
In that mess, they had wired in a short between the circuit for the righthand taillight and the circuit for the marker lights. That short is what was causing my marker lights to come on any time the brake was pushed, or the right turn signal was blinking.

4) A couple wires behind the instrument panel had been cut and rewired in a jury rig. That was what was causing my instrument lights to come on any time the brake pedal was pressed. The jury rigs were probably an attempt to get things working again after the butchery of the tail light harness. I re-spliced the wires back to the factory configuration.

Phew. Glad that's over with.

Andy

[basketcase0302]

Andy,

That's cool!

Somebody had really butchered the rear taillight/brake/turn signal wiring harness when they attempted to wire the truck for a trailer.

I think this is common protocol for the PO's that sell us our trucks.

Basketcase