The Stovebolt Site Forums The Shop Area The Electrical Bay brake lights woes

can somebody please help me. i just got a 64 chevy stepside and i have been trying to fix all the half@%&ed splicing and taping under the hood and dash. well i have my right taillight that is a constant bright(matches the left with brakes applied). no brakes applied with headlights on the left operates normally and the right is bright. any comments and or advice will be so greatly appreciated.

What happens when the lights are off and you apply the brakes? If the right is dim and the left is bright, you need to switch the wires in the right taillight.

the problem is there's 2 filaments in those bulbs, 1 brighter than the other .... for brakes .... someone has them reversed there, you just need to switch the 2 wires to that right light, or take out the bulb, push the socket base up & out, and turn it 180 and re-insert it

Bill

thanks, i just installed new taillight assemblies and the rear harness. ill try switching the wires tomorrow. man i hope that works, i really appreciate the tips. ill post tomorrow weather that works or not.

i did not get to work on it today because of mothers day. but the right never does anything but shines like the brakes are applied, it never goes dim. does that still sound like the wires could be switched. i would think that if it went dim when brakes applied andbright not applied then they would be switched.

You never said what happens if the taillights are OFF when you apply the brakes.

Sorry for dragging this old thread up but I have the same issue on a new harness (I finally found pigtails to replace my crumbling original tail light wires)
What causes brake lights to work but no turn signal and vice versa?
If I swap wires one way I get running lights, brake lights but no turn signal.
If I go the other I get dim running lights, turn signal no brakes.

Have you carefully checked the grounds at the lights? With a dual filament bulbs, when the ground is bad on the light, the electricity backflows through the other filament when it doesn't find a ground. This causes all sorts of symptoms.
Clip a wire to the outside of each socket right at the base of the bulb. Then connect the wires to a good ground. Wire everything normally and try the lights.

Thanks Jim,

I'll dig in post back my progress
Angelo

Angelo, you may not have the "crossover" connections under the cab connected properly, or some other connections are incorrect, the brake lights should only be able to work by going via the signal assembly, see the factory diagram here

Bill

Bill thanks for the diagram, winter and early darkness has given me the ability to get back to this. I checked all my connections from my head light switch all the way back to the tail lights. Everything in between looks nice and connected. I did some troubleshooting and this is what I got:

Brake lights -good most times others I need to hit the brake hard
Turn signals -good
Lights on -good
Lights on + Left Turn Signal -good
Lights on + Right Turn Signal -good
Brake Lights + Lights on -good
Brake Lights + Right Turn signal -good
Brake Lights + Lights on + Rights Turn Signal -good

*Brake Lights + Left Turn Signal -bad
This Causes right tail light to go dark
*Brake Lights + Lights on + Left Turn signal -bad
This causes right tail light to go dim

When the left turn signal and brake lights are activated together I have the issue on the right tail light. I am using an original brake light switch and original turn signal wiring -Only what is in the steering column. Since I occasionally have to slam on the brake to activate the brake lights it makes me think I might need a new brake light switch.

Thanks again,
Angelo

do a visual inspection of the brake light switch with someone activating the pedal, the switch arm can be bent or otherwise out of position, might also use an ohmmeter to check switch function to detect poor internal contact .... problems with rear light function can be caused by poor ground connections, make sure the light mounts are clean and tight, and maybe add a dedicated ground from the light to the frame

Bill

Thanks again Bill, will give it a shot!

Well no joy...
I waited on my shiney new replacement switch. Freed the original one and two rusty bolts and replaced with the new one. It works less than it did before.
Guess it is back to the drawing board.

I'm certainly no expert on this but didn't see this mentioned in your thread, so thought it worth bringing up.

It may be the "cancel" connection in your turn signal switch. With two filament bulbs, one is for your driving lights and the other is your turn signal/brake light. When your brakes are on, and you turn your signal on, your turn signal devise cancels the current to your brake light on that side, and sends current to the signal.

It seems like the problem you are experiencing may be related to this. Bill and others are much more knowledgeable than I am and can comment about this. Good luck! (I don't like electrical problems!)

slightly wrong VEW, when a signal direction is selected with the brakes applied, the signal switch intermittently interrupts the brake light power on that side, so the brake light is actually what is flashing

Angelo, you may need to use a meter on the wiring from the signal unit to insure everything is hooked to the right place, it may be that the circuit from the brake switch to the signal unit is messed up

Bill

Thanks for correcting me Billl

Ok minor update...
I ordered a replacement turn signal harness. In order to get at my turn signal switch I needed to remove my steering wheel. As a result I had to order a puller, my wheel was on pretty solid. My puller finally arrived and I was able to remove the wheel. I started tearing everything out and found bad wiring. The yellow wire was completely chewed and loose. The pink wire insulation was very thin and probably shorting on the column.

I am soaking my turn signal assembly at the moment. Once I get that cleaned and re-assembled I'll report back.

Thanks again

JOY!

I reconditioned my turn signal replaced the turn signal harness. Took the opportunity to clean and grease my steering column and horn assembly. Finally buttoned everything back up and started testing. This one can finally close the loop. Lesson learned... even if a wire seems protected somewhere double check it.

Thanks Bill! Thanks Guys!