While towing, both went out on left side. Any ideas

 

Just for clarification, when saying "while towing", you mean you were pulling something with the jeep? Some of use tow the jeep behind a motorhome, so "while towing" can take on a second meaning. If it was while towing a trailer, when you disconnected the wiring to the trailer, I presume the driver's light (left) stayed dead? The bulbs are in good shape? Do you sense there was a short in the wiring? Possibly a ground issue? I'd think if it was a fuse issue, you would have lost both sides.

 

Need more information.
Do you mean the marker light on the front? What about the front left park light?
Does the left blinker behave normally?

Fuse M17 protects the left front park light, the left front side marker light, and the left tail light.
Fuse M18 protects the same things on the right side.
The blinker lights have no fuses.