76 Dodge 440 model 821F ---under-dash wiring

while investigating the source of a battery drain and the "leaping speedometer needle", I was rooting around under the das and found a small silver cannister (about 1.5" L X .75" Diameter) with white, pink, and yellow-black wires running to it.  One of these wires went to a taped off & empty light-bulb socket.  The cannister was warm even though the ignition was off so I suspected this as a drain on the batter and disconnected the cannister.  Can anyone tell me what this cannister and socket are supposed to do?
Chris

[JerryT]

Chris:
That cannister is the key light delay. It"s only on when you activate the dome light. It also lights up the headlight switch on mine. It keeps the bulbs burning for about 10 sec after you close your door or turn off the dome light.
Jerry

Jerry,
Thanks for the reply & info.  I am assuming that, given its purpose, it is probably ok to just leave this part disconnected.
Chris

[JerryT]

Chris:
Yes you can leave it unpluged, unless it keeps the light on, it is not your problem. I also was looking for an electrical draw, I found it to be the radio. It's a modern one, the memory and clock pull more a bit more than  you would think. I wired it to the house battery and now I am happy. I pulled a  fused  wire in from the house battery relay, I also connected a 12v outlet (cigar lighter style) while I was at it. Now we have a "hot with the key off " place to recharge the cell phone. I know the wiring in these old dodges pretty well and it is mostly ok if no one screws with it. I live in Michigan about 20 miles from the Progressive Dynamics factory that supplied most of the coach wiring systems on the newer A.C.s They have a outlet where you can buy repair parts, new stuff and reman units. They will also look up things and anwser questions, great people! I upgraded my charger/converter to a modern 35 amp one,(you can go larger or smaller) Bought two transfer switches from them (shore/gen to house and then inverter to house) It's all automatic and works great:)
Jerry

[JerryT]

Chris:
Yes you can leave it unpluged, unless it keeps the light on, it is not your problem. I also was looking for an electrical draw, I found it to be the radio. It's a modern one, the memory and clock pull more a bit more than  you would think. I wired it to the house battery and now I am happy. I pulled a  fused  wire in from the house battery relay, I also connected a 12v outlet (cigar lighter style) while I was at it. Now we have a "hot with the key off " place to recharge the cell phone. I know the wiring in these old dodges pretty well and it is mostly ok if no one screws with it. I live in Michigan about 20 miles from the Progressive Dynamics factory that supplied most of the coach wiring systems on the newer A.C.s They have a outlet where you can buy repair parts, new stuff and reman units. They will also look up things and anwser questions, great people! I upgraded my charger/converter to a modern 35 amp one,(you can go larger or smaller) Bought two transfer switches from them (shore/gen to house and then inverter to house) It's all automatic and works great:)
Jerry

Jerry,
Thank you for the good information.  As the dome light was not staying on then I am concluding that this was not the problem.  I also have a more modern radio and should wire it up differently so that there is no drain on the starting battery.
Best wishes.  It is great to have all you guys with more experience and developed resources out there.
Chris