What would cause the cigarette lighter to stop working all of a sudden without the fuse being blown on a 1992 Lexus LS400?

Answer 1

This answer is "generic," in that it applies to ALMOST any problem in which an electrical device fails to operate while the the fuse, or other protective device, APPEARS functional. The fuse thought to be good ["without the fuse being blown"]could LOOK OK, while not being able to conduct electricity. For this reason, the fuse must be CONFIRMED as "good" by the use of a VOM [volt-ohm meter] or a self-powered test light, or replacement with a known good fuse. Once a fuse is confirmed functional, there is only one cause of operational failure, the electrical circuit is not "complete," allowing the electricity to flow through the entire circuit as designed. There could be two causes for this: 1)an "open" in the circuit, in which some part of the circuit [a wire, or the heating element in the lighter itself, a connector,etc.] is cut, broken, or seperated; or 2)a "short" circuit condition, in which some portion of the "hot" wire [the wire which carries electriciy TO the device] is in contact with a grounded object [like the vehicle frame, the frame of the device itself, or any bare uninsulated metal in contact with ground]. Either of these conditions prevent the electricity from passing through the device, thereby preventing its working. To determine the cause of the failure of your lighter to operate, you must find and remediate the fault. I suggest that you "borrow" another identical lighter, which you know is working, and try it in your vehicle's lighter socket. If that lighter works in your vehicle, that means your lighter is defective [an INTERNAL open or short] and must be replaced. Also, "try" your lighter in the vehicle from which you borrowed the known good lighter, and if it does work, then you have confirmed that the problem is in the lighter wiring circuit in your vehicle. If the known good lighter fails to operate in your vehicle, and your lighter operates in the other vehicle,you now know that there is either an open condition somewhere between your vehicle battery and its ground to the vehicle chassis, or there is a short somewhere between your battery and the lighter socket. Getting your lighter to work is a matter of seeking, identifying, and correcting the fault. Good hunting.