Blinks Fast, and Light Stays On.

If you have a bad light bulb it will make the blinker light flash. Check all turn signal light bulbs.

That would be caused by a bad ground connection to either the front or rear parking/turn (probably rear) signal bulb socket. When the ground is bad, the parking light filament with find a ground through the blinker filament, then through the turn signal indicator, keeping it turned on. I have seen this on many cars over the years. Hope this helps, good luck.

could be a faulty relay

Sounds like a bad ground to me, although i am no expert.
i would be checkinh all connections and take it from there, a little wd40 might just solve it short term.

Your right rear turn signal bulb is blown.Replace the bulb and the fast blinking will stop.

mporteous, It sounds like you have a light switch problem. I can't think of any other reason for the running lights and tail lights not working in this situation. Are your brake lights working when the headlights are off and how about when they are on? Do your four ways hazard lights work in these situations? Try all the lights under these conditions. The reason the left turn signal blinks very fast is because one of the bulbs are burned out. Try the left signal and one light (front or back) will stay on and the other will not come on at all. Replace the bulb that does nothing. Do this before you try all the lights in different situations. I think that you will have to replace the light switch. Good luck with this.

It helps if you describe the problem. Does not blink? blinks fast? indicator stays on? right or left? both? do the emergency blinkers work ok? Parking lights work? brake lights?

no year compass stated, so will do 1st year.
USA/ Car?? (we are USA forum so answers default to bingo us)
engine runs ok, all else runs OK> just lamps problems?
Just is very important word in the electric world.
Drivers ok? too. (engine cranks, runs and stays running?) (turns on many meal all that)
gen1 is 2006 to 2016, later is GEN2.
ill pick first years.
seems headlights/binkers (turns sigs) are shorted together or parks.
Park/(aka, tails) may be in the mix.

1: fuses check ok
2: battery fully charged, reads 12.6v key off rested, and 13.3 to 15vdc running,
3: check for wiring damage behind lamps on the effected sides.
and for trailer hitch from H3LL hacks. there? looking is first.
collision damage by other owners, is possible (if 2nd owner you)
now electrics have a chance to perform. good power.
This system is all networked now.. needs to be understood
the first step now is to SCAN it. that's right, what if the communications bus, cant all talking between modules.
those lamps are all run by a computer under the hood
called TIPM , the module insides is called the "electronics module. EM"
it has 4 blinker wires as an output. (not shared a key fact for diagnoses)

you said driver side blinker (left works better)
drivers in UK are on right.
the left side front and rear. my guess , NO not rear)
if true the problem is there, left front blinker.
wire damage there, even the LAMP it self can short, (get new one?)
blinker,
damage at TIPM , can be possible look there yet.
its just a computer and has transistor drivers. to lamps
and if it told to do something, and is told correctly(scans)
then its bad or its output wires are shorted.
try a new lamp ?

Refr. page 50 in the SM ( MK jeep service manual, SM)
and 52.(turns)

the 4 head lamp wires(power) all are seperate at the EM
not parallel at all. independent, x4
and last the park lamps are independant on the EM
that means if the lamps are good and wires good then the EM
is faulting.
or its getting wrong commands, on the CAN-BUSS network
now you know how it works,
better is get the SM and read, it covers ALL this, in vivid details.

The multifunction switch is faulty. the turn signal control.

Usually a fast turn signal means that there is a light out. You should probably check all of your lights, including back-up lights, and turn signals. If there is one out then replacing the burnt out bulb should fix the problem.