This morning my wife left in the blazer, and I noticed that left brake light isn't working again. It only works when it wants to.
It's never blown out, but there isnt any voltage when I get on the brakes.
Tail light and turn signal are working fine.
So I first checked the wiring to make sure there aren't any tears or 'stressed places' in the wires.
Then I checked to see if there was a problem with the trailer light hookup somewhere, and nothing, everything is in working order as far as that goes.
Once the wire goes inside the body, I'm not sure where it goes, or if there is a circuit board somewhere that needs some work.. with it working when it wants to, kinda tells me its a bad connection somewhere...

Thanks

 

you might need a new bulb socket. also check the grounds . try to see if you got power to the wire and not the socket its self

 

Thats.. a really good idea, I dont know why I didnt think of it. Cause all I did was check the socket for voltage, and look for weak spots in the wires. Thanks man!

 

Yep.. for some reason sockets are suspect. I spent over an hour on a chev conversion van, just to find out bad socket.

 

I spent almost all day today working with the blazer, I'm having a engine problem to.
I checked the socket, and they were both ok. Messed around with the fuse box trying to find a blown fuse and everything there is ok to, the prongs of the fuses were clean and making good contact.
After that I proceded back to the rear of the truck, took off the interior panels where the jack is, and found another wire connector. I skinned each wire in front of the connector and checked for conductivity to the sockets, and everything's connected fine.. so I taped them back up.
The Voltage to the lamp = .460V or 460mV
Also, I checked the voltage going to a trailer.. Same 460mV when it should be around 13.8V like the right tail..
Seems like when something goes wrong with it, its a pain to find it.

Thanks for any help

 

It's been a little while, but I finally found the problem.. It is the turn signal switch on steering column. On the schematic, all the switches are right there together.. So I decided to walk out and wiggle the turn signal stick, and voila! there was red light... Live and learn

Thanks pettyfog & giovanni for the help you gave.

 

NP glad you found the problem