New problem with windshield wiper

[RobertK]

Problem with the horn contacts has been solved
(Thanks Dave)

But unfortunately, I have still a problem with the working of my windshield wiper:
The interval switch does not work and he will not stopping if I put the the switch in the "off" setting.
When I put the switch in the interval setting, he turns to the normal (second position) setting and goes on.

For that reason I have first interchange my relais for an other one (same issue)
After that I have change my combi switch for a new one OEM MB (still the same issue)

To be complete:
When the engine is off it behaves different.
Every works normal it looks like.
Oh and my wiper mechanism has been interchanged with a one of the scrapyard but for a certain time it works fine.

Has anybody an idea about this ?

 

[nocfn]

I have not had what you experienced. If it occurs with the new combination switch, with a known working relay then I would suspect one or two other issues. Check that the wiring to the wiper motor plug in is not compromised, and the contacts are clean. Perhaps you can get 12v directly to the motor and see how it behaves when you control the flow to the motor directly. The wiper motor unit needs to have proper lubrication but that obviously isn't the issue. How old is your ignition switch? All your power for all systems goes thru that ignition switch and they do wear out.

 

[RobertK]

Directly12v to the plugs and see how the wiper behaves is good to check.

I do not know how old my ignition switch is.
Where is the ignition switch located in the car ?

 

[gsxr]

The ignition electrical switch is located behind the lock tumbler and housing, and is NOT easy to access or replace.

 

[nocfn]

Thanks Dave. Everything in the car is basically driven off the ignition switch, which can wear out after 25+ years of use, let alone all of the voltage going thru the device. I still vote that the unit running perfectly with 12v directly applied could imply that something is wrong in the circuit to the relay and from the relay. Not likely the switch is bad out of the box....

 

[RobertK]

There are some how-to videos available to uninstall en install a new igniotion switch on YouTube but that is the general W124 instruction for that.
Are there specific 500E difficulties in that respect ?

I think it is strange when I put the key on contact, it behaves normal, the interval is working normal and the wiper mechanism shuts down when I put the wiper switch off.
When the motor is running it behaves different with the symptoms I have described earlier.

 

[RobertK]

Being more clear: the issue I have occured also with the old combination switch and old relay.
It start happen after a while when I had interchanged my wiper-mechanism/motor.

 

[nocfn]

Understand what you meant. The wiper mechanism works when you apply power to the plug directly? That is to say, it doesn't bind at all, the wiring from to motor to the plug end is intact, no issues? Just trying to make sure your testing things before you theow money at this. I understand that it works properly when the key is turned but the car is not running?

 

[RobertK]

Yes, it was tested when I bought the mechanism if it works directly with power to the plug. The wiring to the the plug looks like new and is intact.
Yes it works fine when the key is turned and the car is not running.

 

[nocfn]

Well is there anything else electrical not working with the car running like the headlights on, wiper switch on and requesting to squirt the wipers? Have a helper see if the headlight wipers work. That “might” be a worn switch if other components dont work right. YMMV. May need to go through the schematics and check each item on the circuit. Almost all electrical load goes thru the ignition switch. Not hard to replace but not fun either. Always disconnect battery. If indoors, roll down windows, get seat all the way back with sunroof open. Gets hot on your head under the dash doing work.... if you elect to change switch.

 

[RobertK]

The wiper switch on: the headlight wipers are working but squirting no water on the headlights.
A worn switch could be the case indeed.
I will investigate and preperate the work for that and will interchange the switch if i have some time.
Thanks for the advice !

 

[nocfn]

Be sure to report back. These switches certainly fail and dont go aftermarket, OE lasted a long time, pinch pennies elsewhere.

 

[RobertK]

I will do,
My intention was to buy one from the dealer OEM MB.
Take some time that I will report back about this.

 

[RobertK]

So I have replaced the ignition switch for a brand new one OEM MB, and the issue isn't gone unfortunately.
Any other ideas what the reason could be ?

 

[gsxr]

Being more clear: the issue I have occured also with the old combination switch and old relay.
It start happen after a while when I had interchanged my wiper-mechanism/motor.

Any chance the replacement wiper mechanism/motor is faulty...?

 

[RobertK]

Could be the case of course, but when I put it only on contact, not starting the engine it works well. Very strange. I suspect the relay a bit. The part number was not exactly the same as my own relay has. It is from a later type E500.

 

[RobertK]

Indeed, the wipermotor was faulty,
I have just interchanged it with the old original one and the problem is solved.