Problem started when wipers began working on their own at slow speed only stopped by pulling connector off resistor. - both on "accessory" and "on" at key switch.

When replugged everything ok.

Then lost a/c and front washer pump.

Now when blower switch is at any "on" position, no blow but wipers work at slow speed. No front washer.
With blower on "off" wipers work fine at both speeds and intermittent.

Tried swapping in working steering stalk, heater resistor, intermittent module, fuses and relays and PCM.

Can anyone help

 

Looks like the only thing that all these circuits have in common is the fact that they all pass through the bulkhead (firewall) connector...take it apart and investigate for evidence of corrosion, moisture, burnt, arcing.

 

.......If a wire shorts and get's hot, it will cut through it's insulation and then into whatever is next there under the wrapping in your harness. Even un-related can be connected. Turning on the rear wiper might fire the ejection seat for instance.

With the outer shielding off it's pretty easy to tell if they are melted together.


Btw, Welcome to the forum! I DID have a Celica do just that. A wire to an auxiliary battery in the trunk shorted, burnt through, turned on my wipers and made smoke come out from under the hood. I caught it from a second story window, my wipers going and the smoke from under my hood.