Here is the deal. The alternator must have a small current on the rotor in order to make electricity. Volvo provides that current by making the ground side of all those warning lights connect to the rotor.

When the engine isn't running the bulbs get the ground and they light up. Run the alternator, the ground is lost, the lights go out.

So, your car has a place somewhere that the wire is grounded en route from the instrument cluster to the alternator. And, with no charging, the battery is dead.

The wire in question is red on my 240's, and connects to the back of the alternator. It can be replaced, and re-routed. The other end, on a 240, connects to a terminal in a gray 8-place harness connector on the firewall. I think I saw that same connector on a 740 tucked in just inside the LF fender, about half-way to the front.

Get the battery charged. Find that wire on the alternator. Put the key in run position, but don't start the engine. All the warning lights should be on. Pull off that wire, and check the warning lights again. If they are still lit, that wire is grounded someplace. If they are out, except the oil light, then this simple process hasn't found the problem.

Good Luck,

Bob

:>)