'02 Hyundai Santa Fe electrical problems?

Yesterday, I went to lunch & while driving my car started doing some strange things. When I applied the brakes, my radio went off & the air bag light, the ABS light & traction control light came on. The RPM gauge also started moving in sync with my blinker. It did 4 or 5 times until I got back to work. It did not do it again on my way home & I left with my husband to take in & they hooked it up to a diagnostic machine & said that it was fine. A friend's husband said it might be a wiring harness? My concern is we're about to leave for vacation on a roadtrip to Florida from Texas. I'm afraid to drive it & not know what's really going on. Anyone heard of anything like this????