Brake lights. Electrical gremlin
 

So I've just about got my major electrical issues fixed. I have turn signals, headlights, tail lights, and sort of brake lights.

When the lights are off and you hit the brakes. All four lights come on like normal. However. If the tail lights are active the driver side lights both brighten when you press the brake pedal. The passenger INSIDE gets brighter and the passenger OUTSIDE instead of getting brighter just goes off. What could cause that?

The only wiring that's original is the dash harness. Rear light harness was replaced.

do you own a tester ?
 

http://www.tooltopia.com/kd-tools-26...FRCZfgodCscE4w


best 10 .00 tool for that issue...
stick it in the back of the socket along side the wire and play around

start at the bulb and go towards th e dash .... testing at the plug and continue forward


Usually on my trailers when you step on the brake and a bulb goes out its a ground issue

I have a test light. But I can't press the brake and be at the back of the car at the same time. Maybe on of the metal tabs is not touching and needs to be. I'll spin the bulb some tomorrow and see what happens.

hmmm
 

a long stick/ extension/prybar/ board/10# dumbbell/ neighbor kid/ to the front of your seat wedged in there lightly works fine alsouse an old towel on the front of your seat for padding...

gotta think outside the box ..............

does it do the same thing with the blinker on ? and your lights on?

or does it take brake light activation to make tat one completely go out...

wiggle the bulb ... dont burn your fingers ... swap bulbs...clean the socket inside..

check for oxidation .... at the ground contact...

IF YOUR RIGHT BLINKER WORKS CORRECTLY WITH THE LIGHTS OFF out back

the bulb is good

if the running light comes on on that bulb the bulb is good
'
if it goes out when both are lit up ..... 95% ground issue

just my 2 cents

Scott

I had an 1157 bulb that the little peg was worn off. the bulb was twisted just a little too far and the contact bridged between the bright and running circuits. Voltage was going between them and caused a similar problem.

It's a brand new bulb. But I'll take a look at that.

I'd say it's 99.99% a ground issue.

And I'd say it's probably up front.

Check/add ground from dash to a good chassis point like the metal for the brake mount.
The firewall needs a good ground to the frame.
The frame needs a good ground to the battery.The engine needs a good ground to the frame and to the firewall.

At the rear, the bulbs/sockets need to be well grounded to the sheetmetal.
(clean of all paint/rust/crud)

The sheetmetal should have a good ground to the frame rails also.

Sounds about like the brake pedal bracket is providing a better ground for the circuit when pushed?

:)

I think I got it. I spun the bulb carrier around in the housing some and now it's working. So most likely it wasn't grounding right at the taillight housing. Some of these problems have been intermittent. So we will see how it holds up.

The headlight harness is grounded good. I'm not sure where the dash harness grounds. Maybe I should look and see before I put the gauges back in and make sure it's solid.

The engine can't help but be grounded to the frame. Solid steel mounts on the driver side. Battery is grounded to frame. The body to frame I'll check. And I didn't know about engine to firewall. I'll do that too.

Not sure about '67-'68 models, but '69 grounds thru the steering column mounts (the 2 large bolts just under dash). If you've loosened column to access dash panel, it can create all kinds of electrical issues elsewhere. Make sure these mounts are clean and tight.