On the starter.
The 2003 Ford Expedition has a V8 engine.
The 2003 Ford Expedition has a 4.6 L base engine size.
The 2003 Ford Expedition's engine produces 232 hp @ 4750 rpm.
The 2003 Ford Expedition's engine produces 291 ft-lbs. @ 3450 rpm.
In the case of my 2003 Expedition, it turned out to be a bad starter motor after 55K miles.
The starter is on the radiator side of the engine, behind the engine mount bracket.
You can find an engine diagram for a 2003 Ford Expedition in the vehicle's owner's manual. You can also find it at certain auto stores.
In a 2003 Ford Expedition : The ( 2 valve per engine cylinder version ) if that is what you are asking
The starter on a 2003 Cadillac CTS is located in the engine compartment directly behind the alternator. The starter faces the firewall with the starter solenoid on top of the starter.
On a Ford Expedition : Bank 1 is the passenger side of the engine ( 4.6 and 5.4 )
check starter bendix gear or flyweel missing teeth, make sure engine is physically turning it may just sound like it from starter noise,other then that need a Little more info good luck