Client car (99 coupe) in for some work. Dash apart & bumped the wiper stalk while replacing console trim... wipers came on & parked in middle of the window... uh oh.. some research on here was pointing to failed park/delay board &/or motor failure.

I'm not one to just throw parts at things & had read a few threads that indicated new parts didn't always fix things... so, tear into cowl...

Wipers are cycling & motor reverses as it should but don't park. They actually move back UP the window?? Udders ARE plugged & I'm now thinking water intrusion.

Remove assembly check circuit board. Looks dry & no indication of water. Keep poking and testing, not really getting anywhere. Hit one of my personal cars & loosen enough to peek inside & watch things happen... On reverse, the unit stops & unlatches the detent pin, wipers stay down in the parked position. Failing unit is NOT doing this. The detent stays in place wipers cycle back up the window before stopping...

The picture is of the working unit IN the parked location.

The detent pin is noted in black circle. When parked it is as shown, almost opposite of the notch in yellow circle. When the wipers are "running" (clockwise) the detent pin will be in the notch again shown by the yellow circle.

Now for the problem & solution: in the RED circle (sorry rough) are two things. A tab, blue arrow. and a spring loaded catch, green arrow. This catch is attached to the bottom of the arm and as it rotates clockwise it skips over the tab. When the motor reverses (counter clockwise), the spring loaded catch is supposed pop out to "hit" the tab & stop the rotation. This "unlatches" the pin (black circle) from the notch (yellow) and as the motor spins the half turn counter clockwise the wipers fall into park.

At the pivot point of the wiper arm itself this is a VERY small amount of movement and is caused by the oval/cam shape of the plate moving separately from the arm itself. The torx screw in the middle is the actual shaft of the motor & the cam & plate can rotate independently from each other . The pin & detent slot are what "lock" them together when rotating clockwise.

Pretty much all the grease /lubricant on the failing unit was dry/gone. The little spring loaded catch (green arrow) was stuck and not popping out to hit the stop & cause the park action to occur. Some white lithium spray to get things moving & then some grease to keep things good.

 

Thanks for this post, I appreciate the detailed explanation.

 

Thanks for sharing.