Brake lt. sig.lt. NewTwist

[smoked68]

In my earlier post about the Brake lite and turn sig. not working I had not investigated enough. I tried all the suggestions that you guys supplied to no avail. New bulb, checked the wiring, put the flashers on. Found nothing suspicious, then today they worked. So now totally confused I turned on the head lights. Yep quit working, headlights off, back to working. Confused to say the least. Why do the headlights have anything to do with this??? So to sum up here, as long as the headlights are off I have the left rears working, when on the left rears (turn and brake) are out but the running light stays on. Rt side works as it should when it should. Also from the other post, the brake idiot lite in the dash has gone out??? Go figure. Any and all help welcomed, thanks guys, Mike.......

[ksjh1316]

Sounds like you have the same Gremlin I had last month when my tail lights stopped working. Mine had to be a wire touching metal and the casing being real thin in the area or something cause I got reall pissed and kicked the crap out of my bed and they started working again lol. You never know with a 35 year old wiring whats truely up unless you replace it all.

[Stocker]

Got a feeling it has nothing to do with the headlights themselves... Does it do the same thing with the switch in the 'parking lights' position?

If so, it may be bad when the left rear taillight wire is hot. Check that wiring and the lamp socket, and make sure the ground is properly grounded.

[CrashEd]

The ground wire for the rear lights are behind the marker light probably a broke off wire on it. It just screws to the bed with a sheetmetal screw.
Ed

[wibilly]

i say bad ground as well

[smoked68]

Yep, they're out when parking lights are on also. I have looked for a bad ground, I shall continue to look untill looking is no longer good then I shall rewire the whole bloody mess. A thank you very much. M

[smoked68]

One more thing, my marker lights are cosmetic only, there are no actual lights back there. My truck was built in sept. of 67 as a 68 I guess. Truck was bought brand new by my dad so I know the history. Have a good day my freinds. Mike......

[cdowns]

Originally Posted by smoked68

Yep, I have looked for a bad ground, I shall continue to look untill looking is no longer good

i've always wondered what that means?? have you taken a piece of wire a piece of sandpaper and a couple of sheetmetal screws and tried to establish a ground to fix the problem???

[Longhorn Man]

side marker lights were optional untill 70

[Stocker]

Originally Posted by smoked68

I have looked for a bad ground, I shall continue to look untill looking is no longer good

Looking visually, or testing with a multimeter or test light?

[mvfd70]

The lights may have been optional but the reflector parts were put in all of them starting in the 68 model year. You probalby knew that but someone else may not.

Originally Posted by Longhorn Man

side marker lights were optional untill 70

[Longhorn Man]

true... true. I was just refering to his comment of having lenses with no lights in them.
But you are right, shoulda been more clear.
It's interesting, becouse federal law dicated that all passenger vehicles to be outfitted with lights in 68. GM also got away with not having a standard rear view mirror in the cab in 69 even though federal law dicated it should be there.

[69ChevyLB]

right you are. my 69 C10 has no lights in the side markers and no rear view mirror in the cab.

[smoked68]

To answer the questions, when looking for a bad ground I took my little test light and checked. Then just to be on the over kill side sanded the area and screw from whenst it came. Also the side markers have nothing behind them, no reflectors. They screw strait to the fenders, nothing but a hole and dead air behind them.

[68gmsee]

Okay, from what I'm hearing, your left rear brake lite does not work when the headlights are on. They work when the head lights are off. As far as you can tell you have a good ground and all the other lights work okay... hmmmm

Sounds like not enough juice getting to it. There may be enough when the headlights are off, but when you turn them on, something is sucking up some of that electricity somehow. I'd put a meter on the connector at the rear of the brake light housing and have someone turn the light on and off to see if it goes completely to zero or drops down to a low voltage.

You could also trace the hot wire back from the brake light all the way to the front to see if a wire or connection may be corroded, loose or dirty. Maybe even the brake light switch being bad...

Someone with a wiring diagram may be able to help. Mine are out in the country about 30 miles from here.

[smoked68]

Thanks I will try this today. Its crazy or trying to drive me crazy...

[68gmsee]

This is an interesting problem to say the least. I'm also having a problem with my left side brake lite, but haven't checked to see if it's the bulb or something else. Hopefully it's the bulb...

Just remember that the brake lights are independent of the regular "on lights" when you turn the light switch on. The brake lights come on when the brake switch closes when you depress the brake pedal.

From there that hot wire goes to a connector under the bed somewhere then it separates to the two brake lights.

I'll try to get my book today.