fule pump burned out found this under dash very hot got new one started to smoke key not on but has 12 volts all the time

has 12 volt all the time

 

I'll take this one since there is 50 views and no replies for you..
That mechanical time delay relay has been used for at least 50 years in most mopar vehicles even vans.. {1970 I believe was the first year}.. It's simply a metallic strip wound with a fine wire...If working properly it will get hot.. The aluminum can acts as a heat sink and is usually fastened to something metal to help dissipate the heat further ...It's activated by opening the doors which grounds the relay charging the wound metallic strip..Which will in turn slightly bent the metallic strip completing a circuit to the lighted accessory...Closing the doors deactivates the ground and as the wound strip cools it eventually relaxes and switches the lighted accessory off{about 15-30 seconds} ..So technically the relay will have a continuous hot wire...It's the ground that completes the circuit... If your new relay is staying on past the allotted time frame after the doors have been closed it means there's a constant ground {bad door switch} or a short in the grounding circuit.. Here's the same relay used in a 70 cuda it's fastened to the steering column from the factory for more heat control ..And I'll throw in an internal pic to show the windings for your entertainment.. I've got a whole bag of them I save as spares for my 70 cuda


time delay internals

 

I have the same thing in mine. It burnt my hand so I removed it. I havent put in the new one because it started smoking as soon as it was plugged in. I have yet to find a real reason to use it. I have researched and read everything I can find on it. No one has had any better info than Corky's reply. I hope not having it plugged in isnt causing my current music-less problems.

 

Old thread but great explanation! I wondered the same thing, and I took mine out too because it got hot enough to probably ignite things. Only thing I noticed is my intermittent wipers started working intermittently, but that may not be related.

 

The new unit would probably smoke a little until the oil/assembly coatings etc.. get burned off.. It will get hot enough that you don't want to hold it but not hot enough to melt wiring..I should shoot one with the heat gun and see just where the operating temps are...But yeah it's a little unnerving to see a new component smoking when it goes to work..The simplicity of the unit makes it a cost effective part but I'm surprised there isn't an electronic,superceded mopar replacement in todays world...The function of that part is usually controlled by the vehicles BCM {body control module} in newer vehicles...
If someone had the time you could go through the factory service manual and see just what features are controlled by the time delay relay for your XJ.. Over the years it has controlled a "seat belt" light before the days of seat belt buckle wiring.. But mostly it's used as a delay for your dome light and possibly footwell lighting basically keeping it on for a short time after the doors are closed... . And getting under the dash and stirring up the wiring could definitely reactivate/deactivate a connector for other circuits unrelated to the relay ...
I wouldn't assume that it would have any affect on your radio not working. If you don't have any sound you'll need to start at the head unit and check all connections then the unit itself and work out from there..No sound at all would usually mean it's a main system malfunction {head unit, dash wiring, or if an infinity system the amp}...
So in review, you could certainly unplug the relay and should not see any affected systems that are in use while being operated...