I got an '88 240 in '02. Lot's of electric gremlins. High beams wouldn't go back to low, or wouldn't come on at all. REar lights and all turn signals wouldn't work all the time. Big loads on system in winter, wipers, defroster, radio, lights, and you could feel that it seemed about ready to stall out at idle.

So, new battery with all new cables and connectors, pulled alternator cleaned/checked brushes, AC was inoperable/no 112, so I deleted it,...

the really big thing was to follow Bentley and trace down every ground to everyplace on the engine and body. All connectors were in a state of corrosion some with wires also badly greened up, cut off the ends and soldered on new ring ends and filed off where they connected to body/engine.

On two of these grounds I also ran a 12 gauge dedicated ground back to the battery to make sure the system was wide open.

I'm shocked at how well this has functioned over the last three years. The electrics never fail now. Soon I'll go back and check these grounds again. Normal maintenance.