Right Turn Signal Blows Fuse #12. . .
 

I've checked both front and back connections for the signal, nothing pops out that looks suspicious. No exposed wires, nothing untoward that I can see. Front was a bit dirty and back was pretty clean almost new looking.

I replaced the fuse (again) allowed the gauges to all come up and punched up the right turn signal and all gauges fell. So I think that pretty much narrows it down, ya think?

Where would you look next for the short?

Thanks!

Unplugging all lamps, and switches in the front STILL pops the fuse.
I'm now to looking at the combo swtich in the steering column.
I'll do a search for that, but has anyone changed this switch out on
an 81 SD?
Thanks

I believe it's the combo switch.
I took off the steering wheel (not to hard, cracked at second try with 100 pound son holding wheel and 3 foot cheater) and took out the combo switch. Checked it out, cleaned it up though I saw nothing to indicate a short and put it all back together.
Still pops the fuse in right turns though. Unplugged the combo switch.
All gauges and brake lights work.

So, does this mean it IS the combo switch or could it still be something past the plug for the switch? Should I spend the $130 for a new one from Phil?

Why don't you replace the switch with a working unit from one of your other cars. On the 123 you don't need to remove the steering wheel to remove the switch. Look at Diesel Giants site for the details of removing and replacing the switch.

If it were me, I would trace the wire harness in the trunk going to the lamp. A short is a wire touching bare metal, so look for a pinched harness as it comes up to the trunk from behind the rear seat backrest. Also look were the harness comes from the body inner fender to the right front lamp assembly.

Avoid using the combo switch for the turn signals (you'll morph into the typical DB for a spell..........but, you'll recover) for a day or two. If the fuse survives, you've confirmed that the problem is in the turn signal circuit. It could be the combo switch (but I doubt it) or it could be one of the sockets for the turn signal bulbs (more likely).

I've unplugged the combo switch for now. Just hope it doesn't rain, LOL!
If the fuse stays then I will go from there. Tom drives the car too and he cannot NOT use the turn signal. He does it without thinking so I couldn't let the switch stay plugged in.

And I looked at the sockets, both front and back and they are all solid. Nothing that could cause a short. The back is so clean it looks brand new.

On the up side, I learned how to take apart the steering column. . .



As for replacing with one from another car, I don't think they're the same.
It may be that I could just plug one in at the plug and leave it hanging and try it but don't know. May try that tomo if I can. Glow plugs and relay for tomorrow. . .

Now that you know where the combo switch plug is you could carefully remove the cover from the back of the plug using a small screwdriver to pry it off while it is plugged into the harness (this will keep the wires from coming out unexpectedly). Remove the BK/GN wire (4th from rear in left row), from the plug, then put the cover back on. This will disconnect the right T/S and leave all other functions intact until you locate the short. Even though you can live without turn sigs for a while you might need the horn and it won't work with the combo switch disconnected.