I'm new to this forum so help me out if you can Hope this is in the right place. 2000 Jeep Cherokee, 100,000 mi,. Climbed into car tried to start it, and nothing no power to the gauges at all. Stepped on the brakes, and all my dash gauges pegged all the way to the right then all the way to the left two or three times and stopped. It does The gauge pegging both when you try turning the key to start and pushing on the brake and the gauges will still do this without the key in it all. I've checked fuses under the dash changed one out. This is where I'm at. Tested battery 12.5 volts. With key off any help you can give me with this would be greatly appreciated.

 

My dad’s Grand Cherokee did something like this with the gauges going nuts and it was the ECM. Hopefully it’s something cheaper/easier on yours.