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Marty, Mercedes Technician
Category: Mercedes
Satisfied Customers: 53985
Experience:  Bosch Certified Master Tech. Over 35 years experience.
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Marty, well I replace the windshield washer sensor, found

Customer Question

Hi Marty, well I replace the windshield washer sensor, found the last mechanic I took the car too for the the low coolant light flickering must have blow the 50 amp fuse in the box near the battery as he was messing around. When I picked the car up he
claimed I would need to go to a Mercedes dealer, he was stumped, I find as I said found the 50 amp fuse blown. Don't see any other blown fuses. The low coolant light was flickering when I took it in to him now it is on constantly. At this point I have replaced
the low coolant sensor, washer fluid sensor and the 50 amp fuse. Any thoughts. I did check the fuses in the main panel and t he light switch fuses and they do ohm out good.
Submitted: 1 year ago.
Category: Mercedes
Expert:  Marty replied 1 year ago.

Hi, disconnect the coolant sensor and measure across the pins of the sensor with an ohmmeter. You should measure 110 ohms.

Let me know what you find.


Customer: replied 1 year ago.
I have 109.5 ohms across the pins on the coolant sensor
Expert:  Marty replied 1 year ago.

Ok, that reading is fine. Can you measure the washer fluid level sensor? It should measure 160 ohms. We may need to get to the plug at the instrument cluster and do some tests from there.

Customer: replied 1 year ago.
I have 173.3 ohms of resistance across the pins of the windshield washer fluid sensor.
Expert:  Marty replied 1 year ago.

If you disconnect the coolant level sensor will the light turn off?

Customer: replied 1 year ago.
No,the light comes on with the low coolant level sensor disconnected. I did recheck all the fuses again last night just to make sure i didn't miss one, all homed out good.
Expert:  Marty replied 1 year ago.

Ok, you are going to need to remove the instrument cluster and measure the resistance between terminal 4 and 12 in connector 1 section B. I've attached a picture below of the connectors. You should measure approximately 270 ohms with the connector disconnected. If you have the proper resistance at the plug the problem is in the instrument cluster or there is a poor connection at the plug.