Ok, I have a Kenwood hu that worked perfectly up until I decided to bypass the integrated amplifier in my 99 Grand Cherokee. Now it will power up and play my tunes until I start driving. It seems when I hit a bump it kicks into Protect mode. If I shut the jeep off and turn it on its still in protect mode. If I pull the fuse for a minute and turn it back on it works fine until i start driving again... If anyone knows anything that might help it would be awesome, I've seen threads about people who say it's just a short in the speaker wires but i've already check all those and rewired it. I'm curious if maybe there's something inside the deck thats messed up. Please help?
Did you check to see if the turn-on lead or the RCA cables are grounding/shorting somewhere? Pinched speaker wire somewhere in the car maybe? Could also be a defect in the HU itself or a blown speaker.
If you bypassed an amp, how many speakers are you pushing with the deck? It's designed for only four 4-Ohm speakers, so if you are running more than that, you may have a low-impedance issue.