Wipers not working

[Beefcake35]

So, 79 K10 with air. Wipers were working but slow. Now they quit completely. Looking at the electric design there should be power to the wiper motor constant with the key on. I tested and I dont get power on the yellow wire circled in the pic (with grounded test light). When I hook up 12v to it and hit it with a test light she shines. I tested fuse and its good. Also tested with a meter. I think it goes without saying I have power at none of the pins at the switch. Looks like power is delivered to the ww motor and back to the switch. Loosing what hair I have left here. Thoughts? Not sure where to trace back here. Should I run a different hot wire to that yellow wire and see if it goes? Thanks in advance!

[Beefcake35]

when I say she glows I meant I hook up 1 end of the test light to 12v and touch the yellow connecter my test light lights up.

[Beefcake35]

Any ideas?

[bd]

The "yellow" wire began its life white.  It receives I+ directly from the WIPER fuse.  Probe both sides of the WIPER fuse using an incandescent test light (not LED). 

Tip: when you probe for power, touch the brass terminals that comprise the fuse socket.  Sometimes oxidation will accumulate between the blades of the fuse and its socket contacts, preventing continuity. 

Once you verify power through the fuse to its contacts, probe the white wire as it exits the firewall bulkhead connector.  From the bulkhead connector, the white wire routes directly to the wiper motor and the windshield washer pump solenoid.  FYI - The dashboard switch controls the W/W ground connections.  As long as the switch is properly grounded to the interior left kick panel, you should not detect any power there.

As part of your diagnosis, you can temporarily insert a jumper (protected by a 20-amp inline circuit breaker) between B+ and the white wire at the wiper motor to verify motor and switch functions.