Wanna solve a mystery? Me too....brakes and fuse problem

[Jayman931]

I have a 1969 c10. I replaced the brake switch about a year ago. Here's whats going on.


With no key in the ignition. If I step on the brakes smoke comes up through the steering column.

Also my taillight/brakelight fuse (20amp) keeps blowing as soon as I step on the brakes.

Im assuming if I fix one problem the other will be fixed as well.

Any ideas?

[kwmech]

Yeah, you have a shorted wire in the steering column. My money is on the white wire

[Grumpy old man]

I'd bet a donut the brake light switch hot wire is getting pinched when the brake pedal is depressed

[Jayman931]

Originally Posted by Grumpy old man

I'd bet a donut the brake light switch hot wire is getting pinched when the brake pedal is depressed

I will check that and get back to ya... I hope you are right. Donuts are cheap!

[Jayman931]

Originally Posted by Grumpy old man

I'd bet a donut the brake light switch hot wire is getting pinched when the brake pedal is depressed

Well there is no wire being pinched from what I can see...everything is taped together and out of the way.

This is the first time I have messed with my truck in a week and for some reason when I put in the fuse this time and pushed the brake it didn't pop. Hmmm

The only thing I can think of is when it rains sometimes water gets in the cab and near the fuse box...im assuming if it got wet it could cause a problem. Maybe that's it...maybe its not...

[kwmech]

You said yourself that smoke was coming up the column, common sense would dictate that the problem is in the column, not the fuse block

[Jayman931]

Originally Posted by kwmech

You said yourself that smoke was coming up the column, common sense would dictate that the problem is in the column, not the fuse block

But only when I push the brake...and the key doesn't have to be in. Could it be the brake switch? I don't understand what in the column would be affected by pushing the brake petal.... hmmmmm

I'm about to tear apart the dash I suppose.

[old Chevy guy]

Dead short somewhere in the brake light circuit . When you push the pedal you close the circuit and if the fuse doesn't pop the wire will smoke and burn. Could be somewhere else and that's where the wireing is burning up is in the column . Also consider the directionals are tied into the brake light circuit to so maybe it's backfeeding up into the switch somehow. If it's not doing it now maybe there's a chafed wire grounding intermittently. Brake lights are live even with the key off. Not sure about any of this just throwing out ideas.

[Jayman931]

Originally Posted by old Chevy guy

Dead short somewhere in the brake light circuit . When you push the pedal you close the circuit and if the fuse doesn't pop the wire will smoke and burn. Could be somewhere else and that's where the wireing is burning up is in the column . Also consider the directionals are tied into the brake light circuit to so maybe it's backfeeding up into the switch somehow. If it's not doing it now maybe there's a chafed wire grounding intermittently. Brake lights are live even with the key off. Not sure about any of this just throwing out ideas.

So it doesn't necessarily have to be in the column.

Can I test each side of the brake electrical lines by taking out the bulbs and seeing if they pop a fuse when I push the brakes?

[Jayman931]

Originally Posted by kwmech

Yeah, you have a shorted wire in the steering column. My money is on the white wire

Do have to remove the column to check this? Is this wire to the signal switch?

[Jayman931]

This kinda stood out....could this be it? Not sure what it is to...

[old Chevy guy]

Not sure what that is. Check it with a test light or meter and see if it's hot.

[Grumpy old man]

It looks like the old school aftermarket directional wire where the original would go bad and they would strap a replacement onto the column . I guess I owe you a donut ?

[VetteVet]

That wire looks like the fiber optic light that comes from the cluster panel and runs up to the gear selector under the steering wheel to light it up at night when the instrument lights are on. It doesn't carry electricity. You can easily tell if your column has a short in it by unplugging the half moon connector and trying the fuse and the brakes. If the fuse don't blow then the short is in the column.

If you have a multimeter check the white wire in the HM connector to a ground and see if you get continuity. (zero ohms).

[Jayman931]

I have someone with more knowledge than I do checking things out. He has the wiring diagram and some fandango machine that tests for shorts. He just rewired his old nova so I know he knows a lot more than I do.

He said hes pretty sure no wires that would be affected by the brake switch engaging would be in the column. I'll ask him to unplug the half moon harness and do a quick check anyways.

I'll update in a bit.

[VWNate1]

FWIW ;

The brake light switch's output goes directly into the turn signal switch so that's the very first place your 'Mechanic' should know to look .

The turn signal switch has to re route the brake light current .

[Jayman931]

Are both sides of the fuse supposed to be hot when not in use? (Fuse out)

[VWNate1]

Originally Posted by Jayman931

Are both sides of the fuse supposed to be hot when not in use? (Fuse out)

Hot to the touch ? NO .

Hot as in current on both ends ? YES .

[Jayman931]

We put jumper wire between the two terminals on the brake light switch harness and no brake lights....fuse is in and good...hmmm

[Jayman931]

How would you go about checking the column wires without taking the column apart? Any way?

[Jayman931]

Never-ending this post...it blew....I'm guessing I'm gonna have to take the column apart...damn

ow it's getting weird....hooked everything back up...pushed the brakes....fuse doesn't blow

[kwmech]

When you step on the brake pedal the power from the orange wire at the brake switch flows into the white wire. From there it goes up the column and is split between the green and yellow at the switch. Looking at your picture this would be the black wire with the white tracer on it next to the green wire. Reach under the left side of the column and pull the connector out to where you can unplug it. Step on the brake and I'll bet the fuse doesn't blow. Plug it back in, step on the brake. Although, just moving the harness around a bit could change how the wiring harness became or is pinched, thus grounding out. This is not a mystery, pretty easy stuff.

[Jayman931]

Originally Posted by kwmech

When you step on the brake pedal the power from the orange wire at the brake switch flows into the white wire. From there it goes up the column and is split between the green and yellow at the switch. Looking at your picture this would be the black wire with the white tracer on it next to the green wire. Reach under the left side of the column and pull the connector out to where you can unplug it. Step on the brake and I'll bet the fuse doesn't blow. Plug it back in, step on the brake. Although, just moving the harness around a bit could change how the wiring harness became or is pinched, thus grounding out. This is not a mystery, pretty easy stuff.

We did this test and you are correct. Time to pull out the steering wheel and have a peek. Thank you for your knowledge and advice.

[Jayman931]

Think I found it........

[kwmech]

Yup, that'll do it