You need to reply a faulty condenser C212 (16V/10uF) on the circuit board on the back of the instrument panel, This will cost 10 cents. The dry electrolytic condenser makes the power source of the instrument panel nonoperative. The symptom appears when the weather is cold.
I just repaired my 1994 LS400 with a new condenser instead of paying 1000 dollar for the original circuit boards.
Find how to dismantle the instrument panel by looking at http://www.lexls.com/tutorials/electrical/instrumentcluster.html.
Refer to http://apaqdigital.com/ls400/instrument_circuit.jpg to find the condenser which must be replaced.
Regards Matti H
