Over the past weekend I installed a JVC head unit and used a scocshe wiring harness. The harness came with the 20 some pin hook up, a door chime, and what looks like a fuse box of some sort (ACC plug?) which plugs into a section in the harness that has constant remote ground and illumination.....now when the car is not running you can here that box clicking on and off like a self reseting breaker.... It does not do it when it runs....All of the wiring is good and the system works excellent with one exeception.... At very random intervals my gauges will stop functioning and show error mi for milage... I lose fuel gauge tach speedo and temp....then as i continue to drive a bit more they return and continue normal function...this little black box has a metal tab with hole in it that may need grounding....i tried hooking it up with the ground wire from the head unit and it still did the same thing....Any suggestions or advice would be greatly appriciated....

(Sound system equip)
(6.5 polk audio, kenwood 6x9 5 ways, 2 / 12" mtx subs, 160 watt verge amp, jvc head unit)