The turn signals abruptly stop functioning for hours or days, then mysteriously begin working again. Since the flasher relay is built into the multi-function switch, do you think replacing the switch will cure the problem?
faulty or loose fuse perhaps?
When you say malfunctions, do you mean it does not light at all or that it does not flash?
They do not light or flash when in malfunction mode. Today they worked for a few minutes then stopped. Fuses, lamps are OK. Ideas?
Looking at some info for your car it shows a combination flasher module for the turn signals and flashers, it may be the source of the trouble. It is most likely under the dash near the driver area and may have 9 pins going to it. Since the problem is intermittent I suspect that the problem is due to just a bad connection somewhere. Once you find the module make sure power is getting to pins 1(constant) and 6 of the module with the ignition ON.
To see if the problem is with the combination switch you can try grounding either pins 7 or 8 of the combination flasher module for the turn indicators and pin 9 for the flashers. If things work okay there then the trouble is with the switch area or wiring.
If the problem is happening with the flashers also then the problem may be the ground connection in the combination switch. The turn signal and flasher switch just make a ground connection to activate them.
11/30: It was the combo flasher module. The Jeep dealer insisted it was the multifunction switch, but my mech was doubtful. The part is $42 with about an hour’s labor to install. Pass it on to other JGC owners with a similar problem.
It sounds like more guesswork troubleshooting by the dealer again, at the expense of the customer (but not in this case since you were wise enough to get a second opinion). Glad you got it fixed (at a reasonable price an no wasted money on needless time and parts) and thanks for taking the the time to give us an update. So few posters do that and it is good to know what the results were for all the involved responders.