It was the alternator. Plain and simple.

That check battery light is one of the wires going through the under-the-engine front harness. It is part of the crumbling insulation problem common to 240s 1982-1988.

That harness can be re-built separately from the rest of the harness. There are but three wires, and only two go bad, usually.

Look at the alternator for the thin wire coming from that harness. The insulation is red, but likely there is none present. Remove and reinstall the spade lug connection on that wire, to be sure that the connection to the alternator is good.

There is also a thin black wire from that harness which connects to the oil pressure sensor. It, too, will have missing insulation.

The warning light for oil pressure operates separately from the rest. All the rest operate through that red wire to the alternator.

Check those wires and post back.

Good Luck,

Bob

:>)

--
240s: 1986 244GL, 1988 244GL, and 5 others.

An '83?

A crumbling engine harness comes to mind.........

--
Don Foster (near Cape Cod, MA)