We have a 2007 E-150 van with 5.4L, and when I turn the key, all electrical systems die. No lights, stereo, dings, etc. When I disconnect and reconnect the battery, all accessories work. That is, until I attempt to start it again. I’m not sure where to start on this. Any ideas? The battery has been replaced. Thanks

 

Since power is supplied to the vehicle through the positive side of the electrical system AND a return path to the negative side of the system (not necessarily in agreement with electron theory, but OK for now), that means both power and ground cables and connections must be verified functional ,with good clean connections. The best way to do this is by voltage drop testing. When insufficient power (voltage) is not available to the electrical system , computer networks cannot work and therefore the system gets thrown into "Limp Mode" and self preservation takes effect. When you disconnect a battery cable you allow for a system reset to take place, and now the original power is supposed to be available where in this case it is not because when it is needed a poor connection is preventing that power from being available so the cycle repeats.

Suggest you either check or have the power and ground connections checked.