New starter / alternator, battery won't hold charge
1999 F150, 4.2L V6.
This past Tuesday, my starter gave out. My mechanic installed a new Remy starter and the wiring harness between the starter and the battery. The truck ran fine for one day. Then, while driving (fortunately) about a mile from my home, suddenly the radio and all of the instrument panel gauges shut down. The engine kept running and I limped home, expecting not to be able to restart the engine once I shut down. Unfortunately I was correct. However, after allowing the truck to rest idle for an hour or so I was able to restart it, but again everything shut down shortly thereafter and could not retart until after another "rest".
I noted that when I turned the headlights on and turned the crank, my headlights went out. I then suspected the alternator. I replaced the alternator yesterday with a new Remy 130 amp alternator. I was able to start the vehicle instantly, but now the battery light came on.
I checked the voltage on the battery with then engine off, and it was a little shy of 12V (around 11.50). When I turned the engine on, I noticed the voltage slowly dropping, which tells me that the alternator isn't charging. I boosted the battery overnight in order to get to 12 V, but noticed the same voltage drop this morning when I turned on the engine.
One thing I noticed is that the ground wire from the wiring harness coming from the alternator was not connected to anything at the time I lifted the hood after my gauges shut down (i.e. after new starter, before new alternator). When I installed the new alternator I made sure to connect this ground wire to a screw near the starter relay firewall.
My suggestion would be to check the wiring from the starter to battery. Check connections,check wire routing to ensure not pinched or next to something hot. Then check to see if wires are connected properly.
02 f150 7700 Eaton Supercharged 5.4,4.56 ,4" trailmaster lift,315/75/16s,Reflexxion hood,Expedition center console,08 superduty tails,bumper and tailgate w/ ladder,02 lightning grille,heads,and third brake light,Depot superduty fogs,PIAA airdam and lights,Customized dash triple gauge pod,dash surround gauge pod and overhead console gauge pod,air lift bags,Fortress Super Duty mirrors.