Hello All

I got some problems with a 87 k5 id like to ask about...

im having non existant brake lights at the moment..Dont know when they went dark since its the only light thats not working...

i have power to the brake switch and it also works sending power in the white cable coming from it..

Now i wonder where this white cable is heading.. some googles say it goes to the headlight switch, some say it goes into the turn signal harness..

Does anyone have diagrams of this cable or know where its supposed to go?

I have to have the car for inspection in 5 days, so right now im thinking just to splice a cable from the white one off the brake switch but I also want the real solution :=)

Thank you !

 

The rear brake and turn signals use the same bulb filament so splicing a wire will not result in the proper operation of both systems.

Do your turn signals work?


Here are a bunch of diagrams I found through a quick Google search for "1987 K5 Wiring Diagrams" which are hosted by 73-87ChevyTrucks.com:
81-87 Cab Interior Page 1
81-87 Cab Interior Page 2
81-87 Chassis and rear Lighting
81-87 Front Lighting
81-87 I6 Engine Compartment
81-87 V8 Engine Compartment
81-87 Instrument Panel Page 1
81-87 Instrument Panel Page 2
81-87 computer control wiring
power windows wiring


Cab Interior Page 2 shows the brake switch and the turn signal switch. Circuits 18 & 19 are feeds to the back of the truck for the left & right turn/stop lamps respectively.

 

Hi Swartlkk,

Thank you, youre a better googler then me

I was thinking of pulling 12volt from the white wire running from the brake switch... only to the brake lights as an emergency fix.. I know that the bulb has two filaments, the 1st one is working fine its only the brake filament that is not lighting up.

I can see from your kindly googled diagrams that its indeed going into the turn signal contact in one of the corners...

That should help me follow the wire and try to findout why its not working..

Yes, my turn signal lights work just fine :=)

il save these diagrams now so i always have them with me!

 

Problem solved

Pulled a new cable from the turn signal connector back to my tail lights, all good now

Thank you swartlkk for the diagrams that helped a lot

BR Jonas

 

I’m having a similar issue but my turn signals don’t work either. I think my turn signal switch is broken. Would that cause me to have no brake lights also?

1990 K5 with a 350

 

The turn signal switch could be at fault. I just sent you a private message that should get you to some information that will come in handy for keeping that newer square on the road! And yes, a faulty turn signal switch could knock out the brake lights as well since they all use the same bulb back there.