[tm1100s]

Have a good meter? Set it for amps, turn on the flashers, cover one of the wires with an inductive probe, set it to record min/max to get the reading then use R=E/I. The Shack has the resistors. Look at them all then buy a comparatively big, fat one of the right R.

Experience with this varies so I feel compelled to say this: You're on your own if you plan on sticking anything anywhere in the wiring harness of your vehicle.