When the key is in position KPII, all the warning lights get 12V thru fuse 13. When the engine is off, the exciter wire provides a ground for all the exciter lights thru the alternator.

If you remove the exciter wire from the alternator and touch it to ground, all the warning lights should turn on. Also, check that the alternator case is grounded to the engine block. There should be a ground strap between the alternator case to the engine block.

If all the warning lights turn on then there is a problem with the alternator or its ground strap.

If all the warning lights don't turn on then there is a break in the exciter wire between the alternator and the dash.