auto sensing wipers failed - need help please

[prprandall51]

Hello people, my battery on my E-Class (2005) went flat (I recharged it successfully) and this seems to have taken my automatic wipers out - they still work but only intermittently, if you see what I mean.

There is nothing wrong with the electronics, I think (sensors, relays and switches all seem to broadly do their thing), but the automatic detection seems to work for the first three or four automatic intermittent wipes and then it ceases to wipe until the wipers are switched of and then on again.

Normally, I would put the car into the dealership to stick on Star, but the car is going to its new owner on Sunday and the dealer says they cannot look at the car this week as they are fully booked.

I found something on the internet that suggests pulling and then re-inserting the wiper relays and then putting the wiper control from 0 (off) to 3 (fast) back to 0 and then to intermittent (position 1) followed by a splash of water on the sensor to trigger them in order to reset them.

3 Questions:

1) Does this work?

2) Does anyone know how to identify the wiper relays and where they are?

3) Does anyone else have a suggested fix?

I can ask my friend (who is taking the car off me) to sort it out himself but that seems a bit tough on him (here's your new car, hope you enjoy it, by the way you'd better hope that, if it rains, it rains good and hard).

Any help or suggestions would be warmly welcomed.

Thanks
Philip

 

[bob6600]

Try disconnecting the sensor on the windscreen and reconnecting it.

I had a faulty sensor on my W210 (gave intermittent wipe when switch was on auto), new sensor solved this. Same symptoms if the sensor was disconnected.

Do the wipers work correctly in the I and II positions? If so I would not think the relay is at fault, there may be a stored ghost fault in the ECU due to the battery being disconnected. Checking and clearing (if one is present) could solve it

 

[prprandall51]

Try disconnecting the sensor on the windscreen and reconnecting it...

Thanks for the tips and for taking the time to reply. I don't think the sensor is at fault as the problem came on immediately after the flat battery problem and the sensor still detect rain drops - the auto-sensing just stops after three or four 'sensed' wipes.

The wipers work correctly in both continuous slow- and fast-wipe.

I think your comment about a stored fault in the ECU is spot-on - I just am not in a position to clear the fault via Star.