Short in wiper switch or dash?

[sgr60]

So this is a weird one...

Was going to take the truck out for a drive today and when I turned on the wiper switch, rather than turning on the wipers, it illuminated the right turn signal indicator on the dash. What!?

I assume there is a short somewhere - but I wonder the best place to start looking is. I pulled the steering wheel and looked as best I could at the components in the column, couldn't find anything that looked suspicious there.

I tried playing with some other controls to see what else might be going on, and I found another weird one - when I turn the dash dimmer switch all the way to the left - just before it turns on the cab light - it also illuminates that right turn signal indicator.

For what it's worth, when the turn signal indicator light is on and I turn on the right signal, the flasher does override it and cause the indicator to flash as normal.

I'm completely lost - I'm thinking maybe I have to pull the dash and check for a short back there? I've looked from underneath, can't see much - all of the connections appear to be solid, but I can't really tell what's related.

Any thoughts?

[sgr60]

So this is just too weird I had to take a video. I can't figure where all of these wires would be in proximity one another. Something's bad, just don't know what!

Short in the K20 dash - YouTube

Crazy...

[Sodak]

Let me know what ya figure out please.. my 81 does all that but the high beam indecator.. some one told me to check all bulbs in the taillights sidemarkers.. i did and sure enough there was one.. but it still does it and after a while it will blow the 20 amp fuse but only with the lights on.

[sgr60]

Well... I "solved" half the problem. Upon further digging around under the dash (the wiring has clearly been modified by the PO in ways I really can't figure out) I found a cut black wire coming down from the harness leading up to the gauges. I figured that this must have been a ground for something. When I grounded that wire, all of the symptoms that I was experiencing went away. I have no idea what I really did, or how that could be, but it seems to have helped.

The wipers still don't work (they did before today) but the phantom stuff seems to have disappeared at least. Now I guess I can start to diagnose the more simple problem of wipers that aren't working.

I really would like to know why that wire was cut, and what was causing those symptoms though...

[hatzie]

^^^ Bingo!! You get the gold star. Loose or missing grounds will cause all kinds of strangeness. Bet your gauges work better too.
Electrons are lazy. They will find somewhere strange to go if a better current path is unavailable.

[hatzie]

The wiper switch operates on the ground side of the circuit. Ignition power goes directly to the motor. This way the switch itself doesn't have to handle parking the motor.
Dig into the wiring diagrams and then ask questions. The wires are marked with GM circuit numbers so you can follow the wire through the harness without tracing it with your finger. Pages 2-8 have the circuit #s and wire colors in tables.

The wiper motor hookups are shown as three connectors grouped together on the engine compartment side of the firewall line (PDF page9). The switch is on PDF page10 near the Left hand side of the page.
You'll find the circuit numbers in the drawings of the bulkhead plug as well. That'll give you the proper terminal positions to probe.
You can blow up the wiring diagrams to 300% or so before they start getting too pixellated to read.

[sgr60]

Went out to the truck this morning and low and behold, the wipers are magically working again. Now how is that possible???