If you have the OE sensor on the flywheel, wire it directly to an 85 tach and that should be it. In my recent work building a timing light, I looked at the output of my 85 300D flywheel sensor with an oscilloscope and it was 4 V P-P sine wave at idle, high enough to drive an 85 tach directly, bypassing the EGR computer. Do not use just any VR sensor, it may not have high enough output to drive the 85 tach. Get the OE Mercedes flywheel VR sensor if you don't have one!

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85 300D turbo pristine w 157k when purchased 167,870 July 2025
83 300 D turbo 297K runs great. SOLD!
83 240D 4 spd manual- parted out then junked