Strange turn signal fuse blowing problem

[BajaBronco]

I have a 73 Bronco (one of the late 72-early 73 models), and have a strange problem with the turn signals and brake lights that I've never seen before.

The signals were inop and the fuse was blown. I installed a new fuse, and tried the signals with the car running. I tried left first and got 2 flashes before it blew the fuse. Opened the hood and saw the turn signal pigtail was all messed with and a ground added. I unplugged it and checked the right side pigtail and it was fine. Put in a new fuse and decided to check brake lights and see what they did. Applied brake lights and the left rear didn't work, but the right rear did....tho...it just surged lightly and erraticly with steady brake pressure. I turned the light switch to parking lights and tried the brake lights again. This time, both taillights and all 4 side marker lights did the same erratic surge like a Halloween Bulb (truck is orange).

I tried signals again with brakes and lights off and got 4 flashes to left with front signal still unplugged.

With a good fuse , no bulbs, and turn signal harness unplugged, I have power to chassis side of turn signal harness plug. 3 wires on that plug provide ground and show 12V on my meter: yellow/Black, green/white, and white/blue.

Last test I did just now before having to quit for a while, was to try Right side signals with NO bulbs except cluster indicators, and right side flashes as it should until I apply brake pedal - then it has a major delay, maybe 4 seconds between flashes. Trying left signal again caused only 2 flashes before fuse blew.

Any insights!?

 

[Revelation]

Sounds like there may be an issue with the turn signal switch, or the wiring in the column. That is the common denominator between the turn signals and the brake lights.
If you have a spare complete column, unplug the one in the Bronco and plug in the other and try it.

 

[broncnaz]

Id agree might be the turn signal switch. If its kinda loosen and worn out things can act funny. but I'd also check and clean your grounds and inspect all the wiring you can see as close as possible for any issues.

 

[Viperwolf1]

You have a short to ground on the left rear somewhere. Could be in the column, turn switch, or it could be in the rear harness along the frame. You could unplug the rear harness at the firewall and see if the fuse quits blowing.

 

[BajaBronco]

Aha...good call - I will try that. Late last night I did see a taped bundle I will tear into tonight....it's right by the left rear....thinking an old trailer harness removal happened there carelessly.

 

[bmc69]

Replace the fuse with a .22 round, hit the signal lever, and then go look for smoke in the harness somewheres.


No?

 

[BajaBronco]

Hey- I read that somewheres before!!!

Thinking I don't read the archives first?

Dang tho - I just got rid of all my old ammo with the 69 halfcab I just parted with....I'm about ready to try your idea!

 

[BajaBronco]

Thanks guys, rear harness touching exhaust headers down by the collector. Fixed. Thanks again.