i have a set of silverado ss gauges that i am selling so i took them out and put my stock ones back in. i put in my stock gauges and they are acting weird. when i start my truck the tach and speedo both drop to under zero RPM/MPH. when i manually reset them, they do the same thing. if you go start your truck, you will see that those gauges go below zero, and then jump back up to normal. mine doesn't do that, they just stay below zero. if i drive it they work fine but are just off. any ideas for what it could be? i drive a 2004 silverado btw