98 LeSabre Limited, wipers will not turn on when it rains. Does not activate the washer pump either. When it is not raining the wiper controls are flawless.

Replaced the motor which to my surprise did not come with a control module.

Replaced the module with a 99 from the local yard.

I've read about damp problems that suggest the module is at fault. When it starts to dry out flashing the brights or a right turn signal will activate the wiper control. That suggests the switch in the column but replacing that is a chore.

Is there anything else to check before replacing the wiper switch?

Thanks

Does the wiper switch share a directional switch also?

Yes. Cruise control, wiper, washer, headlights, directional signals.

On the 97 Blazer, Bravada, S10, etc there was a well documented problem of a cold solder joint on the control board. Not sure if your 98 Buick might have the some control board. The fix was pretty easy, pull the control board and apply new solder to the weak solder joint.

When it happened on by 97 Bravada, it showed the same problem you are experiencing. Wipers would work when dry, fail when raining.

Bringing out the big guns on this one. There was a similar problem for the Buicks where moisture actually got onto the board causing problems. Cardone had a write up on that and how their product plugged the holes. That'* why I was surprised when the "new" wiper motor appeared without the module. The module has been replaced with a 99 that should have solved the moisture problem.

I figured out how to attach a picture of the control for Dan SSEi00.