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E39 Wipers Stop - Rain Sensor?

20K views 13 replies 5 participants last post by  arh 
#1 ·
I have a 1999 E39. Wipers work perfectly until I use the rain sensor (intermittent mode). They seem to work and then suddenly the wipers stop returning to the parked position. Moving the wiper stalk makes no difference but the stalk seems to be engaging at each level correctly (ie does not go loose). Switching the car off and back on normally solves the problem. When the wipers have failed the washers are still working in normal and intensive mode.

Any ideas - could it be the relays or a faulty rain sensor?
 
#3 ·
A new wiper relay (tall beige one under the passenger side cabin filter box in engine compartment) is only $14 or so. That's what it sounds like to me.
 
#4 ·
Mine had the same problem a long time back, it was the rain sensor.
I left it as it is, now just the intermittent mode is inoperable, but I use the other modes manually (very seldom and during slow speeds)...I use rain-X.
 
#6 ·
325isBaby said:
ooh, good point...if you do use rain-x (which BMW does not recommend with rain sensors) it will effect the performance of the rain sensor....clean the sensor zone with an ammonia based cleaner and see if there is any improvement with the operation
NO Sir, thought about that, even when the windshield is super clean it doesn't work. The sensor can't be "that" sensitive, then it's not a good design if it is! Anyway, back then, my mechanic tried reprogramming the sensor and it worked, till it's turned off. then the next time it's turned on, it won't work. We tried that several times until he finallyl diagnosed that it was a faulty sensor. I just gave up and will not spend $200 on a new sensor, coz' I don't need a damn rain sensor! Rain-X works for me, and I manually flicks the "wipe once" lever when I'm in slow traffic. Besides, the controls are just at your fingertips!

This is one of the many gimmicks that I don't need, no sensor knows better than myself, the driver, when the wiper needs to be on. So often, unnecessary electronics break down, when otherwise, the car would be so trouble-free!
 
#7 ·
My pathetic bare-bones '99 540/6 doesn't have any rain-sensors. Maybe that explains my bad advice above about the relay. Sorry about that.

The only 2 options I have are heated seats and the split folding rear seats. Pretty much what I'd have picked if only allowed to pick 2....
 
#8 · (Edited)
Do you realize how the rain sensor works and how rain-x is designed to work??? Obviously not. the rain sensor shoots infrared beams at the window and refelcts or refracts based on water content on the window....rain-x puts a film on the window that can screw with the infrared beam it is THAT sensitive....Does anyone NEED a rain sensor? NO, but it is a neat creacher feature for those of us who are unable to multitask while driving!

Like I said clean the window, see how operation is effected, if there are still problems get the codes read out.

PS Eric-there is no such thing as bad advise in my book!
 
#9 ·
325isBaby said:
PS Eric-there is no such thing as bad advise in my book!
Thanks for the chin-up, 325. If you hang around this or any forum long enough you're bound to see SOME bad advice! :p

My advice is still good in that the relay I mentioned is a common failure point in E39s, and it wouldn't hurt to replace it if wiper problems pop up and you're on your original one.

PS - This is my 500th post - so. does that mean I've officially graduated to 3RD GEAR member status?!? EDIT - I guess not....
 
#10 · (Edited)
325isBaby, Yes, I do know how the rain sensor works, and have seen detailed diagrams on them. Also, I do know how Rain-X works.

My mechanic did tell me of the possibility of Rain-X interfering with the sensor after all he tried failed. There were NO codes for the fault. I tried cleaning the windshiled thoroughly, especially the sensor area, even tried with alcohol, and dish washing detergent. No cure. The sensor is DEAD!
 
#11 ·
Well then, that was YOUR situation wasn't it! Maybe arh would have some luck with this tip. I've had many faulty rain sensors in and there are codes (independants may not be able to retrieve) and yes they do just up and die (electrical parts DO fail afterall) you should try the cheap routs before you go buy a new windshield or module what ever the verdict is
 
#12 ·
I did not get round to doing anything about the issue as the wipers did work ok unless I set to rain sensor mode. Yesterday was the first time that the normal mode also failed. I was unable to use the wipers even when the car was switched off and on again. While I was driving they did come back once in about 2 hours of driving and then stayed on as I set the switch to on always.

The next morning they also seemed to be working. I have ordered a relay and will be replacing this in the next few days. I hope the problem is not soemthing else! Will keep you informed.
 
#14 ·
I replaced the relay this evening and it appears to have done the trick as I drove home in the rain for 30 minutes and the rain sensor controlled the wipers fine. Previously it would stop after a few minutes.
Part replaced was - Relay GRN/BRN 61-36-8-384-505

The following website was followed to replace the relay.

Repair notes for the E39 windscreen wiper relay

Hopefully this problem has been solved now. (fingers crossed).
 
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