240 front wiper doesn't work

I have a 1987 240 wagon. When I turn on the windshield wiper, nothing
happens - not on any of the switch settings.

I have checked the fuse and replaced the motor, neither was the cause.

I put a multimeter on the connector block contacts. None showed any voltage,
although both sets showed a decrease in resistance when the switch was on.

Which is the cause most likely to be:

1) the intermittent mode relay;
2) lack of a ground somewhere;
3) bad switch on the stalk; or
4) something else?

Thanks.

 

First, clean the prongs at the fuse and the fuse itself with a small
wire brush or sandpaper, and test with a test light to rule out fuse
issues.

Then, the check for a good ground at the wiper.

There should be a flexible metal piece at one of the bolt points: make
sure it is corrosion free, as well as the attaching point.

You might run a separate ground from another point on the wiper body to
another grounding point on the firewall.

If that isn't it, I'd check the wiper stalk next with a VOM, to see if
the readings change at the prods when you change stalk positions.

Actually, the easiest is to substitute with a spare which is known to
be good.

Finally, substitute the relay (tucked under aluminum shield under
carpet under driver's left foot).