1983 Mercedes Benz 300D Turbo - Electrical Issues

To figure if the trouble is a grounding issue use a jumper wire with probing points and with the key turned to on manually ground each item and see it they then work.

A ground fault in direction indicators usually causes intermittent operation for a while before finally giving up. Where both stop at the same time, it is likely to be the flasher unit at fault - either feed, ground, or simply an old unit failing. Equally likely at the moment in the UK (much snow/cold) is old wires breaking due to corrosion - I needed to fully rewire an '84 Citroen CX due to this. Relays are often situated behind headlights, and older cars have primary fuseboxes under the bonnet (hood) which tend to decay with age. As for earth points, there is usually a main one on the inner wing near the battery, but also near to each device within the car - so one will be hidden somewhere behind the dashboard, usually near the centre for cars which are made in left- and right-hand versions (behind radio is a favourite). Flasher units are mostly on the main fuse board for later cars, but on the column for earlier ones. (change came in the 80's)

Buy the car manual with circuit diagram.....

Thanks, I plan on doing that today. There are some other issues with the car, and the manual would be the best place to start.

Definitely get the manual, and get one in which the wire color code is shown. (VW used to [and may still] actually print the schematic in the wire colors, so you didn't have to squint to read the color codes. Merc may do the same.) But in any case, being able to trace the wiring is essential. Then, any troubleshooting is very straightforward: you can either start at the source and work toward the powered device, or vice versa.

A long time ago I was taught to start in the middle of testing an electrical circuit, not at either end, therefore elimanting 1/2 of the circuit with the first test.

Of course test at the easier access points.

I hope that its color coded too, but for a car of this age I feel it may not be, sadly.....

But I'll keep my fingers crossed for luck in that direction!!

At that age they're likely to be better - if not fully colour coded, you get individual wires shown. Whereas now the books are written by harness: wire4 from here disappears into this harness.........no indication where it goes from there!