Are you measuring on the fuse or on the brass contact?

W124 wiring harness failures are late in the car's production.
You will have wiring problems in a W124 TD, but they will be from bending the harness and will occur at the rear hatch and the doors.....

You can pull up the fuse panel and get to the hard wiring underneath, might be worth having a look see and check for voltage.

Jim

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14 E250 BlueTEC black. 45k miles
95 E320 Cabriolet Emerald green 66k miles
94 E320 Cabriolet Emerald green 152k miles
85 300TD 4 spd man, euro bumpers and lights, 15" Pentas dark blue 274k miles