Losing All Power When Iginition Key Turned

[malbertsEL]

I have a 2007 Expedition EL. This problem has now happened to me three times recently. I have an "auto start" sequence on my truck. The truck will crank and start when I turn the key to crank and then release.

When I turn the ignition key and engage the cranking of the engine, the truck loses all electrical power. After some trail and error, I discovered that disconnecting and then reconnecting the positive battery cable clears the problem and then I am able to start the truck. Any suggestions? Thanks!

 

[panda24619]

thats happened to me with my old dvd deck. do you have an after market head unit or anything aftermarket? could be a bad ground somewhere.

 

[2blackfordrides]

I agree proly a loose or corroded ground.... Or possibly a bad sensor on the tranny( THATS WHAT I FOUND WITH MINE)... Does the radio work when on accessory?