mikem79

Ok, I changed the motor in an 07 150 with the 5.4. Ran great for about an hour then the gauges went crazy and there is a weird sound coming from behind the intake. And the headlights only work on highbeam setting. I'm thinking a ground but have no idea where to start. And the battery light comes on and goes off intermittently. Thanks for help in advance

FST150

Could be the alternator is shot and the trucks working only off the battery, or the battery is drained and no giving enough voltage.

mikem79

Brand new battery and alternator

Especial86

iTrader: (1)

I'd be thinking ground too.. Check them all, the firewall, battery and starter..

fenza89

You probably have a wire plugged into the wrong plug. I've done that before and it can cause a lot of issues.

Especial86

iTrader: (1)

Yeah you could have missed the plug the connects the alternator to the battery.. Ford really made a rats nest of the wiring on the passenger side.. It took a while of disconnecting and rerouting wires with zip ties for me to clean that side up..
Make sure that ground by the ECM is in good shape. The ford supplied ground is thin and cheap, I ended up making a new ground wire there with better crimps and ring connectors..