Brake Lights or running lights not working

[wadewilding]

So I have a problem, and i'm not sure where to start looking as im not familiar with these older trucks. 
I have a 1984 Chevy Scottsdale K20. Its my project, and I like taking it out every once and awhile and driving it. After work last night, I got pulled over for not having brake or running lights.

So before work this morning I went through to see what I could tell was going on. All the bulbs seem to be working. When the headlights are off, flashers and hazards work great until the brake is applied then they come to a crawl for flashing. Brake lights work when the headlights are off. NOW, when the headlights are on. Flashers are slow and only work on the front, no running or brake lights.

Now would this be a ground maybe? or a brake light switch?

[bd]

Begin by checking the rear lamp grounds.  Inspect for broken or corroded black ground wires.  Each rear lamp housing is grounded to the frame (possibly at a common point).  It's common for moisture intrusion to corrode the wires internally.  So if you observe any green salt accumulation along the length of the wire or at its terminations, replace the complete wire.  I also recommend that you replace the flashers using the HD electronic type.

[wadewilding]

What would you recommend BD, as the replacement HD electronic flasher? Is there something through   or stylin trucks or something along those lines out there. This is a project that I am completely new into! Learning as I go!

[bd]

Available from most automotive parts stores under various part numbers.  Here is an example from AutoZone.  It uses an oscillator circuit to switch an integrated relay at a fixed rate independent of electrical load.  The electronic flasher is an inexpensive upgrade from the thermal flashers installed at the factory.

[hatzie]

What would you recommend BD, as the replacement HD electronic flasher? Is there something through   or stylin trucks or something along those lines out there. This is a project that I am completely new into! Learning as I go!

Begin by checking the rear lamp grounds.  Inspect for broken or corroded black ground wires.  Each rear lamp housing is grounded to the frame (possibly at a common point).  It's common for moisture intrusion to corrode the wires internally.  So if you observe any green salt accumulation along the length of the wire or at its terminations, replace the complete wire.  I also recommend that you replace the flashers using the HD electronic type.

The rear lamps, with the exception of the license plate lamps, are grounded to the sheet metal behind the LH tail lamp.  The frame might've been a better place but GM didn't use that for the tails.

[wadewilding]

What would you recommend BD, as the replacement HD electronic flasher? Is there something through   or stylin trucks or something along those lines out there. This is a project that I am completely new into! Learning as I go!

Begin by checking the rear lamp grounds.  Inspect for broken or corroded black ground wires.  Each rear lamp housing is grounded to the frame (possibly at a common point).  It's common for moisture intrusion to corrode the wires internally.  So if you observe any green salt accumulation along the length of the wire or at its terminations, replace the complete wire.  I also recommend that you replace the flashers using the HD electronic type.

The rear lamps, with the exception of the license plate lamps, are grounded to the sheet metal behind the LH tail lamp.  The frame might've been a better place but GM didn't use that for the tails.

Thank you so much for this info! It saved alot of guess work! It happened to be a broken ground behind the tail light. Cleaned it up, put a new end on the cable and bolted it down.

Sent from my SAMSUNG-SM-G870A using Tapatalk

[bd]

Glad it turned out to be such a simple fix.