92 Park Avenue with 140,000 miles. Engine is strong and purrs like a kitten. New battery and alternator tests good. Fuses have been pulled and re-inserted. Positive cable to main fuse block in engine compartment has been cleaned and tightened. Battery lugs have also been cleaned and tightened. When I turn on the ignition the heater/AC blower will come on in defrost mode and the instrument panel is all ***** - voltage gauge, oil pressure, temp. tach and speedometer all jump around after the engine is on for anywhere from 1 to 7 minutes. Instrument Panel does settles down after driving for a while, although voltage gauge reads between 10 and 11 volts even though voltage at battery reads 14.2 with engine running. Fan always comes on at start even though there is no control possible at control panel. Sometimes after dashboard settles down, Climate control will go completely dark with no buttons lit or operational. Other times, fan will continue to blow with no control possible but Econ and Defrost buttons lit. Radio always works. Any ideas welcome!

You will want to doublecheck your maxifuses, as well as the groundbusses, down under the carpets by the front doors. Do you ever have issues starting, or anything else?

Thanks for the reply. All the maxifuses were pulled and steel wool was used on the contacts then re-inserted. The + cable lug to maxifuse bus bar was disconnected and cleaned and re-tightened. I'll have to search for the groundbusses under the carpets by the front doors. Are they on both the passenger and driver'* sides?

One time and one time only in the past 3 weeks did I turn the ignition on and the starter wouldn't crank. I don't think voltage was even getting to the starter as the interior lights didn't dim and there was no clicking or sound at all coming from the starter. After a few tries and about five minutes of sitting and fuming I gave it one last try and it turned over. Almost like it was playing with me.

Also the car did sit for the better part of two years without being driven. All this started after a new battery was installed.

the last two statements make me think its the ground from the engine to the battery or frame, i dont know where it is on your car but if it was bad it would be messing with all your engine and trans mounted sensors at once. my yukon came with a braided one when i bought it and i touched it pretty much vaporized, if you have one of those replace it with a starter or battery cable

Having a hard time finding the ground busses under the carpets by the front driver'* door. Under the carpet between the door and the seat is one big wire bundle . Here are two picture of some connector coming out of the bundle. One shot shows a black cover on the fitting and one shot shows what it looks like without the cover. There are 7 or 8 black wires coming out of this fitting. This isn't what you're talking about right? It was taped to the bundle.

Could this ground buss be on the passenger'* side?

Thanks for your patience.

Well Duh! So, those were indeed the ground busses. Found a link on this site illustrating what I took a picture of the next day. Went ahead and removed the busses and cleaned them - both sides, with steel wool and reassembled applying de-electric grease as recommended. They weren't at all corroded or dirty so I don't think this was the problem. Also disconnected the Climate control head by pulling the connector and this made absolutely no difference in the wankiness of the dash panel. Next step is to replace the BCM. Picking one up on Tuesday. Keep your fingers crossed.