My GPS doesnt work when I plug it in to the lighter socket- think it might be a bad fuse but dont know which fuse to pull out- have no owners manual-

You probably pulled the wiring plug off the back of the socket. Or the fuse went when the socket came out.

Check all the fuses.
But the same fuse works a number of things such as the coutesy lights and an under hood light if equiped. If your interior and any under dash lights work then the fuse is good. You could also have a bad ground or a bad socket. Or even the GPS plug may not fit will in the cigar lighter socket well enough.

When your lighter lit on fire it could have melted the casings on the wires shorting them together. This would cause the fuse to blow every time you use the lighter. Also it is the same fuse for both the lighter and obd (which in your owners manual will be called Data Link Connector, or DLC). Replace the fuse but don't use the lighter. When you plug in the DLC it should work just fine then try the lighter. If fuse blows you have to fix the wiring to the lighter or possibly the lighter socket.

check fuses to see if blown or try another adaptor in the socket lighter to see if it works if it dooesnt then the fuse if it does work oh boy a long and wonderous journey awaits you i am only joking it could be serious but check fuses first its easier

Sometimes the lighter has a small built in fuse. Get a test light and check the center pin of the socket, it it does not have power, take the socket out and check the wire, it the wire has power, the fuse is bad. Sometimes you have to buy the whole socket to get the fuse, but I done know about your particular socket on a Jaguar.

it dont matter check ALL fuses because some fuses feed other fuses and are not labeld such

check the wiring behind the lighter and recheck fuse panel for a designated lighter fuse or the lighter housing may be bad if u have power to the lighter than replace lighter unit any auto store sells them

go to ths link to download an owners manual free.

http://www.edmunds.com/ownership/howto/articles/120189/article.html

all you need to do is buy a cheep test light in the 5-10 range. ground the test light and touch the metal in the fuse you do not need to take the fuse out. check both sides of the fuse you will see 2 metal pices on the back of the fuse were it tells you how many amps the fuse is. that is what you touch with the test light. the light should light up if not the fuses are bad. if the fuse is good take the test light and ground it again you can clip it to the side of the cig lighter socket. and put the test light prob into the cig lighter socket becarefull not to touch the sides of the socket and just touch dead center bottom and if the test light does not light up you know your Cig socket has burnt out

fuse # 16 in the instrument panel fuse box 20A yellow