GibMax

So, one problem after another. See my post about the turn indicator too.

I found out my brake lights are not working. Trying to figure out how to diagnose problems like this. I bought a cheap electrical probe (a bulb with an alligator clip and a pointed end). Stuck it in the brake light switch (attached to the brake). Got a good result (the little light in the probe lit up) when I connected the alligator clip to a ground and stuck the probe into one side of the brake light switch.

Now what? I've looked at the taillight. Those are good. I'm getting the taillights coming on when I turn on the headlights. Still no brake lights and the turn indicators don't work.

I can't figure out how the brake light switch is supposed to work. I thought that the two wires would just be connected when the brake was pressed. But when I connect the probe to the two wires then press on the brake, the probe light doesn't light up. Should it?

How hard is it to replace the brake light switch? I can't see how it is attached.

Jaded

Well, your on the right track. My first 68 has this same problem, and like you I started at the bulb and worked my way forward. Everyone thought it would be the brake switch, but like yours, my indicators in back would fail.

Two things cropped up finally. One was a cruddy connector in the drivers side kick panel, and the other was a cracked turn signal switch. If you pull off the steering, you can use your probe to see if your switch is working. Mine was very intermittant mostly due to a combination of heat and the switch position.

Last but not least, once I fixed the switch, my right rear brake didn't work. I almost went back to the wiring, but again started at the bulb...and it was the bulb.

GibMax

Well, I'm not sure if I'm capable of pulling the steering wheel. Sounds like a lot of wires could be involved. Don't they sell a special steering wheel puller tool too?

4reboy

I believe places do sell a steering wheel puller tool, not sure how much it is though.

As for the brake lights, inspect your bulbs carefully, there are two filaments in it, one that will light up with the headlights and the other that will light up with the brake switch. It could be that the 2nd filament that lights up with the brake switch is burnt out but you can't see it. This happened on a different bulb for me, I think the turn signal I don't remember, so it could be a possibility for you.

also the connectors for the brake lights could be corroded or something, causing it to not have a full connection, so check the connectors and brush them with steel wool or fine sandpaper if you think they should be spruced up.

-David

GibMax

Okay. I've already cleaned the housing assembly that holds the bulbs. I'll take another look at the bulbs themselves.

Another odd clue. I connected the two wires for the brake light switch together with my probe. The light in the probe lit up. So, this means to me that the circuit is good. The brake light didn't light up so that confuses me. If the problem were caused by a bad brake light switch then I'd think the probe closing the circuit would cause the brake light to come on.

Another oddity makes me think the problem is in the steering wheel. With the probe connecting the two wires on the brake light the probe light will go off when I turn on the left turn indicator. The light stays on when I turn on the right turn indicator.

Jaded

Depends which steering wheel, some are a bit more complicated. But no wires except two for the horn.

One bolt holds the wheel on, you take that off and you can use a puller, or do it the only way I've ever seen it done, and that's by pulling on the wheel with your knees and giving the shaft a sharp rap with a ball peen.

The only other thing to be aware off is when putting it on, align the notch in the back of the steering wheel with the stud in the turn signal off cam (it's closest to the steering shaft).

kalli

you said you checked for 12V on the brakelight switch.
If you have that there it still doesn't tell you if the switch actually works unless you have tested that you have 12V on both pins while you press the pedal.

So from this I'd start all this by pulling the brake likght switch connector of the switch.
Then you should have to pins on the connector. bridge them with a small piece of cable. you might have a bit of a sparking when you bridge from one to the other.
With that bridge in place check in the back of car if the lights are now on.

If they are then the problem is the switch. If they are still off, then check for 12V+ on the cable towards the bulb ...

obviously check the fuses as well

jlg2002

How about the obvious, check for power at the rear lights when the brakes are on. This would tell you if you have a TS switch issue or a bad ground.

GibMax

I've purchased teh shop manual (on CD). Took a look at the diagnostic information. Not very helpful. Some of the diagrams look helpful. I see the wire colors listed and routing.

GibMax

So, the saga continues. I've purchased a new brake light switch. But the brake lights still didn't work. When I short the contacts on the brake light switch with a wrench the brake lights work. Oh, maybe it's not the switch. Perhaps the switch when it is riding down the distance of the swing of the pedal it's not getting enough force as resistance to close the switch. Or, maybe the new switch doesn't work either.

How can I increase the resistance that the switch meets with? I took the post that connects to the switch and I pulled it off the switch and turned it clockwise several times. Not sure if that is the proper way. Still didn't work. Should I try turning it some more? Or is this just going to raise the pedal height?