Mercedes-Benz Forum banner

21 - 24 of 24 Posts

·
Registered
Joined
·
6,592 Posts
mrboca, some update. Today I removed the IC and measured the whole loop resistance across Expansion coolant tank level sensor and Windshield washer fluid reservoir level sensor. The Reading I got of 154.8 Ohms. Way lower then I expected, but match what you have told me.

My reading of Windshield washer fluid reservoir level = 33.6 ohms

whole loop resistance across Expansion coolant tank level sensor and Windshield washer fluid reservoir level sensor = 154.8 ohms

It means Expansion coolant tank level sensor 154.8 ohms Minus 33.6 ohms = 121 ohms, which is good.

So my problem is the Windshield washer fluid reservoir level sensor, which suppose to be 145-185 ohms and I am getting only 33.6 ohms.

Thank you mrboca, I will get Windshield washer fluid reservoir level sensor for $16.

Below are some photos from today.
It is great that you were able to get that measurement from IC connector. In the future avoid poking into connector from the front unless you have correct pins to do so. Spreading female connector may lead to never ending errors in that circuit.:smile
 

·
Registered
Joined
·
333 Posts
Discussion Starter #22
Witek_M, thank you for your recommendation. I will be careful to don't spread strands of test wire into IC plug.

I typically use tin wire for testing so strands of wire don't break and cause issues. I used these same tin wires on large expansion gas turbine in oil & Gas control system for testing.

Anyhow I will be careful.
 

·
Registered
Joined
·
333 Posts
Discussion Starter #23
mrboca, some update. Yesterday I got the new Windshield Washer Fluid Reservoir Level Sensor. I remove the old washer fluid level sensor and install the new washer fluid level sensor.

After installation, I measured the resistance of new washer fluid level sensor and it was right on the money 176.8 Ohms.

After I connected the connector back to new washer fluid level sensor and started the car, no more coolant low level message. I connected my Autel diagnostic tool, No more codes, all cleared up.

So here the conclusion. Even though I was getting Coolant Expansion Tank Low Level Warning, and Code on reader as short on wiring of washer fluid level sensor/Expansion coolant tank level, the Problem was the Windshield Washer Fluid Reservoir Level Sensor.

It is bad design by Mercedes to display wrong message on IC when the problem was somewhere else. Anyhow the issue is now resolved.

Big thanks to all of you for your support. Special thanks to mrboca for info on all the resistance of individual level sensor and whole loop resistance.
 

Attachments

·
Registered
Joined
·
5,415 Posts
Thanks for reporting back. Yes it is a bad design. More like an afterthought. Instead of providing individual sense circuits, they provided only one, and some voltage coded signal to determine the status of the levels. Probably some bug in the Instrument cluster firmware too. At least it is a relatively cheap fix.
 
21 - 24 of 24 Posts
About this Discussion
23 Replies
6 Participants
mrboca
Mercedes-Benz Forum
BenzWorld.org forum is one of the largest Mercedes-Benz owner websites offering the most comprehensive collection of Mercedes-Benz information anywhere in the world. The site includes MB Forums, News, Galleries, Publications, Classifieds, Events and much more!
Full Forum Listing
Top