Turn signal/headlight problem

I have a 98 S10. When I put the right turn signal on, and the headlights are NOT on, everything is fine. If the headlights are on, or if I turn them on while the turn signal is on, the turn indicator light blinks fast. When I walk around the back of the vehicle, the turn signal on the right side is blinking, the reverse lights on both sides are also blinking, and the license plate lights are both blinking. If I turn the headlights off, everything returns to normal. I've checked for burnt bulbs, and I've replaced the tail/turn/brake bulb. Where should I start looking for the problem?

there is a ground splice pack at the rear of the vehicle on each side grounded to the frame, check these ground splice packs to see if the wire broke off at the frame or the splice pack connector. hope this helps

could also be a burned out bulb, you did chech all bulbs right?

if the truck has a trailer light wire harness that doesn't just snap into the trucks light harness, it may be wired wrong

if the truck has a trailer light wire harness that doesn't just snap into the trucks light harness, it may be wired wrong

I've checked all of the bulbs, all are okay...I've even replaced a few for good measure.

I've got no trailer light wire harness.

I did notice today, that while sitting in the driveway, engine running with no headlights on...only driving lights, that if I put the right turn signal on, it operates fine. If I shift into Reverse, I get the fast blink and the right turn signal flashes fast, the reverse lights flash fast, and the license plate lights flash fast. If I go to N or D or P, back to normal flash on only the right turn signal.

:banghead:

ok, replace your backup light switch