Yes, that small rubber box you found behind the battery with the 7 wires sounds like the light checker. Two versions were used on these. The Standard model used a simpler 3 wire unit. It monitored just the brake light and is easy to eliminate - you just unplug and remove it. Your Special model got the more complicated 7 wire unit. It monitors both the tail light and the brake light. Power for the tail light passes through it so you can't just remove it without adding a jumper wire to restore the power path to the tail light. Both units trigger a warning light in your dash if the brake light on the Standard or the brake or tail light on the Special burn out. Mine's gone, along with my reserve lighting unit. I actually had no problem with the light checker but when I switched to an L.E.D. tail light bulb, the warning light in the dash came on full time. I guess the low voltage use of the L.E.D. fooled the unit into thinking the bulb was burned out, so I removed it.