Brake lights and blinker. Help please.

[willem445]

Today I went through the process of rewiring all of my lights. I completely rewired the rear taillights harness with new wiring and I replaced the rats nest front light harness with a near perfect one from a donor truck.

How do the brake lights work? I followed this wiring diagram..



There is also a tan wire that I traced from the rear up to the firewall and it enters the cab. Does this wire connect to the brake light switch? How does that get wired into the brake light harness?

All of my blinkers now work except for the front drivers side. Both rear blinkers work and the front passenger side works fine. All of the front lights light up when I turn on the lights but the driver side front blinkers will not flash at all. I replaced the flasher on the fuse panel and the 20A fuse looked good still. Any idea what is wrong with it?

[hatzie]

The turn signal lamps use the same filaments as the brake lamps.
The brake light wire runs from the pedal to the turn signal switch in the column then out to the bright filaments in the tail lamps.

This is a description of the same type switch in a Ford Mustang. The GM switch works pretty much the same way.
http://1970mgr.org/_TurnSignals.htm

[MikeB]

Originally Posted by willem445

All of my blinkers now work except for the front drivers side. Both rear blinkers work and the front passenger side works fine. All of the front lights light up when I turn on the lights but the driver side front blinkers will not flash at all. I replaced the flasher on the fuse panel and the 20A fuse looked good still. Any idea what is wrong with it?

Sounds like the problem is wiring or connector. First thing to do is see if you have voltage to the socket's contacts. Using a voltage tester like the one below, the tester's lamp should flash when touched to one contact (turn signal) and stay on constantly on the other (parking lamp).

I worked on a car last week where the left front turn signal wouldn't work. Turned out that the two contacts in the socket (on brown fiberboard) were not lined up with the contacts on the bulb. Hard to explain, but I ended up re-keying the fiberboard and everything worked fine. Maybe not your problem, but worth a look.

[willem445]

Originally Posted by hatzie

The turn signal lamps use the same filaments as the brake lamps.
The brake light wire runs from the pedal to the turn signal switch in the column then out to the bright filaments in the tail lamps.

This is a description of the same type switch in a Ford Mustang. The GM switch works pretty much the same way.
http://1970mgr.org/_TurnSignals.htm

Which one is the correct bulb in the taillights? Would I wire it into say the light green wire going to the taillights, then those bulbs would light up assuming my brake light switch is still good?

[JacobSchni]

make sure bulb is in the correct position. make sure theres a good ground from harness to bed and bed to frame

[willem445]

Originally Posted by JacobSchni

make sure bulb is in the correct position. make sure theres a good ground from harness to bed and bed to frame

I will check my grounds and bulbs next time I go home. Thanks.

[JJLT1]

1157 is usually the tail/turn/stop bulb.. its a double filament bulb..

on your diagram
the lite green is the backup lights..
the brown is the tail lights and side marker lights..
yellow is left turn and stop lights
dark green is right turn and stop lights..

that's purty normal on a chevy..

[willem445]

Originally Posted by JJLT1

1157 is usually the tail/turn/stop bulb.. its a double filament bulb..

on your diagram
the lite green is the backup lights..
the brown is the tail lights and side marker lights..
yellow is left turn and stop lights
dark green is right turn and stop lights..

that's purty normal on a chevy..

Yep, I rewired the entire rear taillight harness and followed the same color scheme so it is correct. Just dont have any brake lights right now. Everything else works. Bought both 1156, 1157 and 168 bulbs and replaced everything correctly. Im thinking its either my brake switch or the fuse could be bad.

[JJLT1]

x2

brake lights go thru the turn signal switch too..
see if you have brake light power thru the turn switch..

usually
orange is power to the brake switch
white is out of the brake switch to the turn switch on the column,,
yellow and green out of the turn switch..

[willem445]

Originally Posted by JJLT1

x2

brake lights go thru the turn signal switch too..
see if you have brake light power thru the turn switch..

usually
orange is power to the brake switch
white is out of the brake switch to the turn switch on the column,,
yellow and green out of the turn switch..

I just received a new switch in the mail. Next time I go home Im going to do some debugging and try and figure out whats going on.

[JJLT1]

let us know

[willem445]

Figured I would post an update to this thread. Went home over Easter break and finally got some time to work on my truck. I went through and wire brushed most all of the obvious grounds I could find. Also pulled the steering wheel and replaced the turn signal switch as well as the brake light switch. some ground wires under the dash were pretty bad so I replaced all of those. I know have working brake lights, hazard lights, right signal and left signal lights. My only issue is when I turn on my right signal the left side lights blink as well but very dim. After thinking, I remembered that I did not polish up the ground for the one side rear taillights so Im assuming that ground is what is causing this. Thanks everyone for the help. One step closer to getting my truck on the road.

[JJLT1]

wtg Will
yea sounds like a ground..

['76 Big Block]

I went through similar issues with my '76 after replacing my right front fender.
I'd removed the ground wires going from the battery to the core support (I also replaced rotted battery tray), and after reinstalling everything, I had weak turn signal lights, good hazard lights, no high beams, etc.
My problems turned out to be poor ground connections at the core support----
Hope your issues are that simple---- good luck!