Need some electrical help. Brake lights are not working correctly (1 Viewer)

[cruiserhunter]

Hello all,
Ran into another problem after fixing the headlights:

So, Rear lights tail lights turn on when I turn the headlights on.
But, When I step on the brakes, the passenger side light does not brighten as the left drivers side does.
So my brake light on the passenger side is not working.
Do i need to chase down a short somewhere, or is there some where else I should look.


Thanks in advance.

Cheers,
Patrick

 

[duncanrm]

You've confirmed the dual filament bulb is ok?

 

[John McVicker]

^^^
That‘s the 1st thing to check.

 

[cruiserhunter]

Hmmm,
It looked appropriate when I took the cover off. I will check again when I get out of work..... if it is just a bulb... I will be so thankful.


Thanks much!

Patrick

 

[dbbowen]

try swapping the bulbs from left to right, if the dim one is on the left side... you know your problem. If not, you could try cleaning contacts in the bulb socket or trace the wires to see if there is any frayed wires or anything like that?

 

[cruiserhunter]

Thanks dbbowen,
GREAT IDEA. I will switch and see. I looked for frayed wires, but it was dark. i will clean the contacts as well.

Y'all are smart

Cheers,


Patrick

 

[CruiserTrash]

Beyond swapping the bulbs from side to side, here’s a couple other things to check:

1. There is a ground under the tailgate at the very back of the body work. You have to lay on the ground and look way up onto the farthest back of the cargo area floor pan. It’s a ring terminal bolted in and it’s gonna be covered in grime and you won’t see it at first. Clean that up really well. Even if this isn’t the problem your lights might get brighter as a result.
2. In earlier 60s all of the electrical for the back of the truck comes down the driver’s side to the area by the washer fluid bag. From there a sub-harness plugs into a connector, goes under the truck, and services the passenger side taillight. Check that the connector is seated and get rid of any corrosion. Check the wire run. Check that the connections behind the passenger side taillight are good. Later 60s (after 85?) have a separate harness running down the passenger side and I don’t know anything about that.
3. Remove the bulb and look in the socket. Check for corrosion.
4. Check that the wires that are soldered & crimped to the back of the taillight housing haven’t fallen off.

My previous 60 had such big rust holes and so much water got in the area behind the cargo panels that all the wiring was corroded to hell. I was chasing the same problem you were and when I went behind the cargo panel the wires turned to dust in my hand. Complete disintegration everywhere I touched. Spent the whole rest of that day building a completely new rear harness from scratch. That was fun. Fingers crossed for ya.

 

[cruiserhunter]

Arggggggg.....
So, First thank you all for the advice.

I tried the bulb trick and no luck, the passenger side light did not brighten when stepping on the brake

I cleaned out the connectors really well, hoping that was the problem. But that did not help and then.....

I blew a relay!!!!!!! That I just replaced!!!!!
I was stepping on the brakes to see if the rear brake light would turn on and the head lights shut off and a buzzing sound came from under the steering wheel...
Do I have a short somewhere? UGGHH!!!


Any help would be appreciated.

Thanks in advance.


Patrick

 

[67azcruizr]

ground then check grounds, if that checks out clean your grounds

 

[cruiserhunter]

Sorry, Had some health stuff to take care of.

1. Cleaned off the ground under the rear bumper and EVERYTHING is brighter... but brake light still did not work.
2. Found a jumble of wires under the rear bumper where the previous owner (I got this truck in the 90s) had a hitch light connectors installed. I cut out the hitch stuff, bridged the lines and the brakes lights WORK!
3. I have absolutely no idea how I blew that relay! It is replaced now and my headlights are working...... for now.


Thank you all for the help and for the advice.

Patrick

 

[cruiserhunter]

Analyst,
Sorry for the ignorance.. what does "ohm out the relay" mean and how do I do this?
I am goggling to see if i can figure this out.

Thanks for the advice about a possible short, I hopefully have some time this weekend to check all the wires under the truck and then in the engine bay.

Thanks in advance.


Patrick

 

[CruiserTrash]

Get a multimeter, set it to resistance, and put the test leads on contacts 85 & 86 of the relay. I guess if it's an OEM relay you won't have the contacts labeled as such. You're testing the resistance across the coil.