The dimmer is usually the problem if the lights are ok. You don't need to solder a wire. The dimmer just unplugs & you can use 2 female spade lugs connected by a jumper wire & plug them back on to the dimmer terminals. The other plastic nut is just below the speedo cable. After loosening both you can then tip the assembly up & remove it through the hole in the dash & access both the bulbs & the dimmer without removing the wiring. This is useful for checking the dash lights & warning bulbs. The brake warning light could be the one for the parking brake on. If the bulbs are ok {check by substitution],then short the parking brake switch,located under the handle when lifted. If the light goes on [with ign. on]then the switch is defective. If not,then check wiring to dash & ign. & ground at the switch. Good luck!

Mike M.