Triumph Repair: Wipers wont stop (park) on Spitfire 1500, spitfire 1500, column switch

Question
I have an '80 Spitfire 1500.  My problem is that I can't get the windshield wipers to stop after turning them on and off again.  They continue to run even when the switch is in the off position unless a) I wait for several minutes after turning the wiper switch to off, or b) I try several times to move the wiper switch from on to off position at precisely the right time.  Do you have any tips on how I could diagnose this problem?

Answer
Jim,

The way that parking wipers work is that in addition to the power signal from the wiper switch there's an additional power feed to the wiper motor and a contact plate inside the wiper motor.  When the wipers are off the "park" position the internal contact setup ensures that the wiper motor will continue until back to the park position, unless the switch is still energizing the motor.  

What you're describing is most likely a problem with the column switch in that the contact in the column switch is sticking in place when you move the switch, keeping the wipers going.

A less likely problem is that dirt/debris have built up in the wiper motor itself and are shorting the park circuit, causing it to go for a few more cycles.

Unfortunately the wires at the wiper motor end are in a plastic block, making it tough to pull the feed(s) from the switch to isolate the problem.

What you might do is set up a voltmeter to measure the voltage on the brown/light green and the red/light green leads.

Cheers,

Jim