Don't know- I don't have one to look at either. Perhaps pmckechnie can answer that question.

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'83 300D, 126K miles.

Yes, the electromagnetic gauges used in Mercedes are self regulating.

I took apart a fuel gauge from a 83 380SEL. There was 1 resistor used for calibration, 1 inductor probably used for power surges or spikes, an electromagnet coil that had 2 windings that opposed each other, a magnetized disk inside the coils that could turn and move the needle. There are 3 connections, power, ground, and sensor input.

I guess you could call it a modified Wheatstone bridge where parts of the bridge also functions as part of the meter. I am not an EE so maybe others could comment on weather it is a Wheatstone bridge or not.

Does this help any?

Paul

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84 500 SEL (307,xxx miles)

It sure sounds like a modified bridge circuit to me.

Probably not a true Wheatstone bridge with 3 resistors and the sensor but the operational concept is similar.

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The OM 642/722.9 powered family
Still going strong
2014 ML350 Bluetec (wife's DD)
2013 E350 Bluetec (my DD)

both my kids cars went to junkyard in 2023
2008 ML320 CDI (Older son’s DD) fatal transmission failure, water soaked/fried rear SAM, numerous other issues, just too far gone to save (165k miles)
2008 E320 Bluetec (Younger son's DD) injector failed open and diluted oil with diesel, spun main bearings (240k miles)

1998 E300DT sold to TimFreeh
1987 300TD sold to vstech

Yes it does thanks! Can you post a pic of the380 SEL fuel gauge internals?

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85 300D turbo pristine w 157k when purchased 161K now
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked