Brake light problem... help.

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Cobra67
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Brake light problem... help.

Post by Cobra67 »

I only have brake lights when I have the turn signal on. Doesn't appear to have anyone tampering with the wiring so I'm hoping someone has had the same issue.
Cobra67
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Re: Brake light problem... help.

Post by Cobra67 »

I'm sorry. It's a 1970 F-100. Forgot to mention that part lol
71Fe2O3
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Re: Brake light problem... help.

Post by 71Fe2O3 »

Check out the wiring diagram available on this site. The circuits for emergency blinkers, brake, tail and marker lights, as well as turn signals, go through the turn signal switch. There is a tutorial on this site that shows how to replace the switch, and reproduction switches are available from the usual vendors. It's a bit time consuming but not too hard, and, in my case, it solved several previously perplexing problems. While you are in there, you may want to replace the horn contact springs, which may break when you take the steering wheel off. My turn signal switch repair job took me down a rabbit hole that lead to rebuilding the steering column and filling the cracks in the steering wheel while I had everything apart.
Fred

1970 F100 4WD short bed, 360 engine, very rusty plow and yard truck

1971 F100 2WD long bed, 302 engine, on the road

1968 F100 2WD long bed, 360 engine, stripping for parts
Cobra67
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Re: Brake light problem... help.

Post by Cobra67 »

Thanks so much. I was already thinking it may be in the turn signal switch. I have no emergency flashers at all and as I said I only have a brake light when my turn signals are on. I do have park lights tho.
71Fe2O3
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Re: Brake light problem... help.

Post by 71Fe2O3 »

That sounds like the signal switch to me. I spent a lot of time probing around with a test light, scratching my head and trying to figure out how so many electrical circuits could have glitches in them before I looked on this site, spent some time with the wiring diagram, and noticed the centrality of the turn signal switch in all the problematic circuits.

Swapping it out made a world of difference, not only in the lights, but, because the "ears" of the switch that are bumped by the canceling cam on the steering wheel were broken, a new switch renewed the self-canceling ability of my newly functional and predictable turn signals.

Be aware of some challenges, which I believe are mentioned in the tutorial.
Make a drawing of the wires in the plastic connector, and also check them against the wiring diagram (in mine, a previous mechanic had some in wrong) before you take it apart, so that reassembly is less confusing.
The square-headed bolts that hold the shifter collar to the column tube flange can be quite fiddly. I put small pieces of some "easy-tack" stuff (chewing gum should also work) on the heads to hold them in place and then threaded the nut on slightly to hold them in pending final assembly.
To thread the new wires through the channel in the column I ran a long zip-tie up through the channel (a piece of stout wire should also work), taped the wires on and pulled them through.

Another switch that can give you trouble is the emergency flasher switch, which is also in several circuits. It, like the turn signal switch and horn contacts, are available from Carpenter and other popular suppliers.

Finally, be aware that, if your column bearings are bad, you may notice an abnormally wide space between the wheel and the shifter collar that will prevent the canceling cam from doing its job. This is caused when worn out bearings in the column allow the steering column to drop down relative to the shaft when you remove the steering wheel. If this is the case you may wish to consider rebuilding the column. For a few dollars more...
Fred

1970 F100 4WD short bed, 360 engine, very rusty plow and yard truck

1971 F100 2WD long bed, 302 engine, on the road

1968 F100 2WD long bed, 360 engine, stripping for parts
Cobra67
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Re: Brake light problem... help.

Post by Cobra67 »

Thank you. I do have a gap there. The self cancelling does not work. Have to manually cut them off and it's hard to find the neutral location on the turn signal because it is do worn. Also the emergency flashers are not working. I'll check that out tommorrow
71Fe2O3
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Re: Brake light problem... help.

Post by 71Fe2O3 »

I just did that whole thing (turn signal switch, emergency flasher, column rebuild) on mine. It was a few hours worth of work, and I got to take it apart and put it back together again a couple times before I got it just right. It sure is nice to have it working properly now.

To take care of the gap you need to remove the entire column and replace the bearings and bushings-you can find information on this site, but it is fairly obvious if you take a look at it. I used an impact driver to remove the 15/16" bolt holding the steering wheel to the shaft, and a ball joint separator (pickle-fork tool) proved helpful in coaxing the splined end of the shaft out of the gear box. Treat the shaft carefully (don't damage the threads and splines) because, as far as I could tell, nobody makes them, and used columns can be expensive.

The internal bearings and bushings differ depending on whether you have an automatic, floor shift or column shift, or, as was the case with mine, if your column was previously replaced with one from the 73-79 series. If you have time to have the truck apart, strip it down, check out all the parts, then place the order once you are certain what you have.

The mechanism is pretty simple, and you should be able to figure it out once you get it apart. There are several build threads here and elsewhere.
Fred

1970 F100 4WD short bed, 360 engine, very rusty plow and yard truck

1971 F100 2WD long bed, 302 engine, on the road

1968 F100 2WD long bed, 360 engine, stripping for parts
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sargentrs
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Re: Brake light problem... help.

Post by sargentrs »

If you choose to rebuild your column, this might come in handy http://www.fordification.com/forum/view ... hp?t=72274
Randy
1970 F100 Sport Custom Limited LWB, 302cid, 3 on the tree. NO A/C, NO P/S, NO P/B. Currently in 1000 pcs while rebuilding. Project thread: http://www.fordification.com/forum/view ... 22&t=59995 Plan: 351w, C4, LSD, pwr front disc, p/s, a/c, bucket seats, new interior and paint.
1987 F-150 XLT Lariat, 5.0/C6 auto.
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