My 2004 GXP seems to loose electrical power when I go over bumps, particularly train tracks. I noticed it when the heater fan would go out intermittently going over the bumps. Now my fan motor will not come on at all. Any help with be appreciated. I have checked all the fuses.

Check the ground strap that bolts to floor pan under the back seat. They are not well engineered.

do your headlights or dashboard flicker?

what sam said, is it centralized to the hvac system or alot of different things, if so what things.