bhuter24

I have been searching the web for almost 2 weeks now. I have not read any post that is covering my problem.
My wipers on GL 450 only works if I take the certain steps in certain orders. I just bought this vehicle so not sure how long the problem existed.
Here is what is happening:
My wipers on 2007 GL450 only works if I turn them on at the highest speed before turning the vehicle on. Once the vehicle is running if I turn the wipers off and then turn them back on immediately at the high speed, it will start again. If I wait little (like 3-4 seconds) the wipers will not start again. To turn them back on again I have to stop, turn the vehicle off, then turn wipers on highest speed and then start the vehicle and only then they will stay on.


I have checked both fuses and they are fine. I had bought a used motors and that one does the same thing.


I called couple dealerships and they said they never heard of this problem before.


Anyone had experience this before or anyone can help me diagnose the problem?

Fourdiesel

It sounds like there is a defect in the module which controls the wiper motor, not the motor itself. In other words, the switch on the steering stalk 'tells' the controller to perform a certain way and that info doesn't get communicated effectively. Only a computer scan of the system will detect if it is the switch itself (unlikely given the circumstances described) or the module.
Get the dealer to provide a price for a new control module for the ww.

bhuter24

Humm the dealer! I guess I will have to take it to them. Will make an appointment since the winter is coming and wiper is a must.


Thanks
Will update once I get it diagnose done.

alx

How old is your battery? Weak battery will result in described behavior.

If battery is good the wiper stalk needs to be diagnosed with star.

If stalk is good wiper relay is faulty. If wiper rely is good wiper control module needs to be relced.

Good luck

bhuter24

The battery is old. I had the test done on it and Autozone told me that it's weak. I didn't change it yet because it kept the charge and was working fine. I'll change the battery tomorrow and will update.

Thanks

bhuter24

Can anyone tell me what the voltage it should show at the wiper connection? I checked and it showed like 6v. I'll check it again tomorrow morning.

bhuter24

Hello Alx,
I replaced the battery but it did not make any change to the wiper behavior.
What is "star" can I do that diagnose?
Thanks

alx

star/ das is the mb-specific scanning and maintenance tool to interface with the vehicle computers. it contains specific diagnostic steps to troubleshoot most electric/ electronic modules within a mercedes.

i am afraid you will need this tool if you were to continue troubleshooting your wiper problem

bhuter24

Update: Took the GL to the dealership. They charged $130 for diagnose. They describe that someone swapped the relays between starter and wiper. They swapped them back and now wipers are working fine. For a curtesy they replaced a running lamp that was burned out.