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Stan, Mercedes Technician
Category: Mercedes
Satisfied Customers: 3526
Experience:  Technical support engineer
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I have a 2002 C180 estate 2.0 litre auto/petrol RHD.90,000

Customer Question

I have a 2002 C180 estate 2.0 litre auto/petrol RHD.90,000 miles, full main dealer service history. The problem is that most times that you operate the indicators left or right, but maybe more to the right, the wipers will immediately action for one or mostly many sweeps. They also DE action if you slam the bonnet or maybe the driver's R H side door. They will sometimes cancel by randomly operating the wiper/trafficator switch. The car is an AVANT GARDE and appears to have rain sensing wipers. The battery voltage is 14.6 running and 12.8 ignition off. I have replaced the wiper/trafficator switch and cleaned the contacts on the flasher bulbs on the 4 corner lights but not the mirror or wing repeater lights. I have renewed the front headlamp mounted bulb holders as each one had one of its contact 'ears' eroded away 20 per cent or so by electrolosys or arcing. Currently no malfunctions are displayed by the instrument panel albeit recently it suggested that the NSR stop lamp bulb was faulty which cured itself and no visual fault was found upon stripping and inspecting. The trafficker ticking is at the normal speed, all The hazard lamps are bright and flash at the regular speed. The wipers will stop if you release the bonnet without raising it. I am an ex mechanic, I feel that a little product knowledge will save me a lot of frustrating exploring, can you help please.

Submitted: 3 years ago.
Category: Mercedes
Expert:  Stan replied 3 years ago.
Stan :

The wiper motor is actuated by the SAM module in engine bay fusebox, depending on the inputs from wiper switch and rain sensor. Wiper motor also has an end position switch in it.
So the problem can be in wiper motor itself, front SAM module, wiper switch or rain sensor. If the wipers come on when rain sensor and wiper switch are disconnected- it would mean that either the motor or the front SAM are faulty. The SAM function and the comands it sees can be checked with Star Diagnosis computer. Some independent MB shops have this diagnostic computer besides authorized dealers.

Stan :

The wiper motor plug's pins 2 and 4 are for the park position switch. According to the wiring diagram, switch must be closed in park position, and open when in the middle.

Stan :

The plug is located in engine bay fusebox.

Stan :

If this contact is not closing properly, the wiper motor will run on.

Stan :

best regards,