brake hazard turn signal problems

[Rickster]

Started with blowing fuse when hittings brakes. After months and trying to find the problem still cannot figure out what is wrong.  Have checked wiring grounds, cannot find problem.  Everytime try to do something, the situation changes, ergo something may work and something else not work.  Take to long to type every thing done or tried.
With fuses out and switches off, should there be continuity between both turn and park light wires (every combination) to the back of truck:  dark green, yellow, and brown?  There is no continuity between the back up light wire and other three:  light green.  Can not see any damage to sheathing from front to back of truck.

What can a body do?  Just spend the $500 for new wiring harness?

1979 C-10, 6 cylinder 250, no accessories.  Just a bare bones truck with three on the tree.  So simple yet complicated.

[bake74]

     It is a little hard to understand what exactly you are trying to say, so bear with me through these questions and I am sure we can get you some help.
     Let us start at the first part of your post.

Started with blowing fuse when hittings brakes.

   
 Since you said fuse I assume there was only 1 that was blowing, which one specifically was blowing ?

  After months and trying to find the problem still cannot figure out what is wrong.  Have checked wiring grounds, cannot find problem.  Everytime try to do something, the situation changes, ergo something may work and something else not work.  Take to long to type every thing done or tried.

     From your post it seems that you are inclined to think the problem is stemming from the rear brake light system.  You said you have checked the grounds, so I will assume that means the rear wiring harness ground that connects the rear of the truck to the frame.
     Have you tried this ?, disconnecting the rear wiring harness of the truck, ( by actually pulling the wiring harness plug apart in the back ) and seeing if you still blow the fuse ?
      If you do this and you do not blow the fuse this step likely can eliminate a short in the brake control switch which the brake pedal pushes when you depress your brake pedal.
      Just from my personal experience with my 74 when I first picked it up.  The lights ( front and back, running,park, turn signals, and brakes ) would act like you are describing, never the same thing twice in a row and never working right.  I finally traced a couple of problems down.
     1:  was a short in the engine bay connector that ran to the back to supply power the rear of the truck ( I had to cut off one of the actual rubber connectors and put a new one on, the short was inside the molded piece ).  2:  My actual ground wire for the rear was bad, not the ground connection but the wire itself, ( there must have been enough wires broke inside the sheath to cause to high of ohms count because it would not make a good enough ground ).  3:  Inside the rear light housings for the turn signals and brakes, the corrosion was so bad that it was causing a direct short between systems, after cleaning them all out really good and fixing some of the back wiring connections on the boards ( the one's that the brake, turn etc light sockets are attached to ), I finally got all my lights ( front and back) working right.
     The reason for that long story is to let you know that it might be more than 1 problem, and might just be somewhere where you might not expect.
     Don't give up, it can be fixed, we just need to know more and sooner or later someone on here will have gone through the exact thing you are battling I bet.    Good luck and looking forward to helping you out, if not me personally some one will be able to.

[Rickster]

Initially brake/hazard fuse was blowing.  Then the turn/park fuse blew.  Must have blown 10 while trying to figure out problem.  At one time thought problem was in right rear part of wiring.
Last time blew brake/hazard again with rear harness unplugged.
Have never seen a ground between box and chassis.  If there is supposed to be one, where is it supposed to be exactly?

[rich weyand]

No ground between box and frame rails.  There is a ground wire from the battery to the alternator bracket, a ground strap from the rear of the engine passenger side head to the firewall, a ground strap from the front of the engine driver side head to the frame rail at the steering box, and ground wires to sheet metal at both the headlights and at least one (on some models two) ground wire to sheet metal at the rear light housings.

What you are describing sounds most like insulation burned/worn through on the wire run from the brake pedal switch to the rear lights.

[Rickster]

"strap from the front of the engine driver side head to the frame rail at the steering box"
Have the oher grounds described but not one at steering box.
Last time blew hazard/brake fuse was trying to hold hazard switch in but it does not stay in.

[rich weyand]

That ground strap you are missing grounds the frame and box (and rear lights) so that they agree with the engine, cab and battery about what 0 volts is.  You have an iffy (at best) current path back to the electrical system from your rear lights.

Mine runs from the upper power steering bracket bolt to a threaded hole in the top web of the frame rail at the steering box.

[Rickster]

Do not have that ground on a 6 cylinder with manual transmission.

Did discover had left a wire from frame to sheet metal which was attached with wire from negative terminal and right front lights was not connected.  Missed it when removing to clean connections before.  Although the flasher has continuity it did not work.  The clicking does not seem to have a good or the right rhythm though.  Now turn signal, hazard and brake lights are working.

Now if I can get the tag lights to work again.  The horn would blow when grounding while putting on steering wheel.  After the horn button has been put back together or on it does not work.  Another grounding problem?
And now the fasten seat belt light stays on continuously.

[Rickster]

Do both flashers need to be th same type or style?  Put the old one back in for turn signals because I burnt up the new one.  Put one of thoses that is supposed to be loud in for the hazards that costs three times more than what I think is a reed switch type.

[Rickster]

After many hours over a period of months, chasing a gaggle of wild geese, and spending way to much money for naught, hoping problem is resolved.

Lessons learn
1. Check grounds
2. Check grounds
3. Check all ground connections.
3. Loosen ground connections and clean.

Loosened tag lights and moved around slightly to find the sweet spot to ground. Horn works after tightening steering wheel nut more to make contact.

Believe the final resolution was cleaning ground at left front.

[rich weyand]

Yeah, grounds is where to start.  No ground, no go.  And the grounds on vehicles are typically done much sloppier than the hots, because they can't short to ground and cause problems!

And thanks for letting us know!  It helps a lot to know how people solved their problems.