My rain sensor seems to have failed. It wasn't functioning when I bought the car and I can't seem figure out what the issue is.

It is the older version of the relay- the one with the potentiometer on it. The green LED doesn't light up when the wipers are placed in the intermittent setting.

I removed the relay, and opened it up and could see nothing visible, including a thorough examination of the circuit board. I dialed the pot up as far and as low as it could go with no change. I also checked all the fuses, including the unlabeled accessory ones.

Here are my thoughts: It could be the sensor itself, although I am not sure how it would fail.

It could be the wiper stalk that has failed. I could test this by putting in a normal intermittent relay if I had one...

Or it could be the relay. Part of the relay has to be working, as if it is completely removed, the wipers won't return to their resting position. Reinstallation fixes this issue.

There is a three-prong plug out to the sensor. I am assuming that there must be a way to test the output/input. Thoughts?

Any help would be appreciated. I live in Seattle, so you can imagine that I need my intermittent wipers!

Bump. Anyone with ideas?

I would bet it is the relay. I know it is made by a German co. I will see if I have the company name at the house tonight.
The windshield sensor use IR light. So you might turn it on then use a digital camera to see if the IR LEDs are firing.

Thanks for the tips.

I will pull the relay this afternoon and see what I can find out. Since there are only 3 pins out to the sensor, it seems as though there should be a way of testing the relay output/input. I am guessing one is positive, one pin is negative and the last on is the switched return from the sensor. I wish I had a wiring diagram...

couldnt find the rain sensor.... maybe this will help.

Ferdinand,

That is very helpful. Thank you. I just got a reply from the PO and he said that when the windshield was replaced, the shop couldn't get an OE applicator (sticker) to attach the sensor to the windshield. He said it was working before that. If the relay and the wiring is okay then I may have to R/R the sensor with a factory OE sticker. The substitution may be blocking the IR...

Cheers,
Tom

no prob.... gl, and let us know how you make out.

Great idea on using the digital camera to check the IR emitters. Here is the result. Clearly the aftermarket applicator is not blocking the IR. Now to start testing the wiring... it is not the stalk, since the sensor is getting switched power. I am going to pull the relay/control unit and see what I can.

I have always assumed that the green led that indicates that the system is working is on the inside of the sensor, in the center, behind the mirror. If that is the case, it is not illuminating...

Looks like the green LED at the center needs to be ON to show the system is ready according to this http://www.whiteson.org/boxster/mods/rainsensor_tsb.pdf

Not much help. Good luck.

Check the stone. If it's wet turn the wipers on??

Medieval weather station
Stone is wet..... Rains
Stone does not move..... Calm
Stone moves something..... Lighter wind
Stone strongly moves..... Storm
Stone is white..... Snow
Stone is not to be seen..... Fog or stone pinched

Did you ever resolve this issue?