I have no way to determine if the wires need replacement or not. Also I could not tell much from the pictures.

I would think you are in bad need of a wiring diagram and you have not mentioned that you have any sort of a Service Manual.

The Haynes type Manuals are not noted for being good but they usually have some wiring diagrams in them. There is several being sold used on eBay.

People say if you can access the Mercedes EPC you can look at a free Mercedes Manual.

If it is still being sold there is a W115/W116 Service Manual on CD from the Mercedes Classic center and there is a bunch of copies people are selling on eBay.

I have the CD Manual set for my W123 but it will not work on a computer with 64bits. It works OK on 16 and 32 bits.

Sometimes there is also the original Mercedes printed service Manuals on eBay. On My W123 the wiring diagrams are in one of the Chassis Manuals. The Engine Manual and the Chassis manual are seperate books. On the W123 there is 2 volumes of the Chassis Manual.

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84 300D, 82 Volvo 244Gl Diesel