Wipers are not working?

Tiny
BHAMDOC1973
  • MEMBER
  • 2011 MERCEDES BENZ C300
  • V6
  • 2WD
  • AUTOMATIC
  • 85,000 MILES
Checked fuse #10 is good and tested it with a probe as well. Tested the wire to the wiper motor while wiper turned on and it has power and ground. I made sure the hood was closed as well. I know these may not work if the hood is open or even the door. Turn signals and high beam work on that stalk. I am almost sure these have no relays.
Sunday, March 10th, 2024 AT 4:58 PM

7 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Hi,

If you have confirmed there is power and a ground to the wiper motor, it should work. If it doesn't, chances are the motor itself has failed.

I attached the wiring schematic for it below. There is a relay involved, but again, if there is power at the motor, the relay or fuse must be working.
Let me know if this helps.

Take care,

Joe

See pics below.

Note: I had to cut the schematic in half to make it readable. I did overlap the two so you can follow from one to the next.
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Sunday, March 10th, 2024 AT 9:07 PM
Tiny
BHAMDOC1973
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  • 2,010 POSTS
I see. There is a 3rd wire which I am guessing is the signal, should this wire have specific voltage once the wiper runs? Right now it just shows a number without beeping for ground or positive and doesn't say volts, I am guessing its signal.
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Monday, March 11th, 2024 AT 4:34 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Hi,

Which wire is getting voltage? Is it the red wire? Also, brown is a signal ground. Do you have continuity to ground via that wire?

When you check these things, make sure the key is in the on position, wipers are on high speed, and both doors are closed.

Also, you mentioned that there is no beep when checking ground or power, only a number. What is the number? Which wires are you referring to? (Wire Color)

Let me know.

Joe
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Monday, March 11th, 2024 AT 6:38 PM
Tiny
BHAMDOC1973
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  • 2,010 POSTS
No. There is power. There is ground. I am talking about the 3rd wire in the harness connector. One is ground one power and the third one just has a reading like a 10.2 for example but not volts and light does not come on to indicate if it's ground or power. Also, yes, I turn the wipers on and doors closed bit these cars have something under the hood that prevents wipers from coming on, not sure where that sensor is.
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Monday, March 11th, 2024 AT 6:47 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Hi,

Okay, there is no power. Did you check fuse 10 in the under-hood fuse box? See pic below. If you checked the fuse, did you confirm there is power to it?

Joe

See pic below.
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Monday, March 11th, 2024 AT 7:26 PM
Tiny
BHAMDOC1973
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No, like I said, there is power. There is ground, and I checked fuse 10 first thing and it's good and has power on both sides using probe and pulled fuse and has power, so my question is, what is the pink doing, a signal wire?
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Monday, March 11th, 2024 AT 7:32 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
The pink wire is a LIN (Local Interconnect Network). It is a network protocol used for communication between components in modern vehicles. Basically, it is how the modules communicate with each other.

Based on the idea that there is power and ground present, the motor is likely faulty. However, to check the LIN, you can scan the can-bus to determine if there are diagnostic trouble codes indicating a problem.

Here is a link showing how it is done:

https://www.2carpros.com/articles/can-scan-controller-area-network-easy

With the right scan tool, you can actuate the wiper motor manually to see if it functions.

Let me know your thoughts.

Joe
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Tuesday, March 12th, 2024 AT 6:58 PM

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