yachtengine

Stumped on this electrical problem. My 04 F150XLT, 5.4L battery light came on intermittedly while driving. Battery gauge in panel looked ok on volts. Noticed lights dimming and all of a sudden battery gauge went down very fast. Was driving at night. Barely made it to my drive way. Instrument cluster went crazy, abs lights, then cluster went dead.
Check my battery, low amps. 1] REPLACED with battery off the shelf. 2]Check alternator and REPLACED.
Now battery light will come on after engine runs about 3 minutes, also engine feel like it has no power, and idle speeds are fluctuating. 3] Rechecked alternator installation, wires and connections all secure. 4] Checked fused link and sense wires, appear to be ok.
Any help appreciated.

Good old Bill

Hi there and welcome to forum. Ok, a massive electrical failure occured. Most likely the alternator failed (for what reason, is the ?) and then the battery went dead and thus the computor lost its memory and has to be re-educated. Now, engine doesn't perform well. Is this right?
Now comes a bunch of questions. Is this a new battery off the shelf or something just laying around? When connecting this (new) battery was there any shorts or sparks connecting the terminals? Questions seem trivial, but it is nice to know what we are dealing with.

Fast Hampster

Welcome to the forum. I can only guess about what happened to your old alternator, most probable cause is one of diodes shorted. It caused very quick battery discahrge (and probably damage), and it also was followed by significant voltage lowering. Read the error codes from computer to figure out if any sensor or computer itself failed because of low voltage. May be it's missing TPS readings, and therefore you have that idleing fluctuation and low engine power.

yachtengine

Thanks for the input. Bill and Fast Hampster. First, battery is new off the shelf. Installing the positive cable a small spark. I also hooked up a friends OBD II Blue Point Scanner. NO Codes noted. Started the engine and it came back as a P0622, field short. Check the alternator and field wire 14.0 to 14.3 volts. Computer????. What is the good, bad and Russian

Fast Hampster

Small spark is okay, it does it all the time. P0622 means Generator Field "F" Control Circuit Malfunction. Since your alternator is new and tested ok i think you should start with re-checking alternator connectors and both engine and body groundings before spending any money for new parts. I'm not sure but there can be a fuse in an alternator control circuit - i saw it in some vehicles. If it's possible to check the computer or temporary replace it with working one for a test run - i guess it would be the best second step.

P.S. good way in this case is step-by-step failure tracing procedure. Bad way is replacing every possible part at once without any positive effect. Russian way - sitting around the truck with 2 other guys and 3 bottles of vodka and no snack at all. After running out of vodka, figuring out that the nearest alcohol shop is 10 miles away and the truck's still not running. Repairing it with one paper-clip and a lot of swearing, and while driving it back home with more vodka crash into the tree so noone can ever figure out how you could fix it.

kickinit

does the F-150 have a limp mode for when the battery is dieing like some other cars? It may put the computer in limp mode cutting alot of power to important accesories (to only drive it to get it to a shop before the cut off) but may need to be reset, not sure on the F-150 though.

Good old Bill

Hey Ham, as long as no one got hurt, wish I was one of those guys. Actually thought that uncontrolled behavior was a pattented American thing.

Fast Hampster

Bill i'm sorry for challenging American uncontrolled behavior priority, but i have some reasons for doing it

bigxj91

Thats sounds kinda like what is happening to me. When im driving the battery light flashes on, lights dim, the alarm light that flashes in the dash turns red then everything goes back to normal....I also have a new battery. I thought it was electrical. I took the truck to the shop they said it was the fuel pump and fuel pump driver module....I didnt get it fixed going to get a second opinion... Anyone know where i can find directions on intalling a fuel pump?

my truck is an 05 5.4ltr fx4

jacksonahonda

bigxj91 the same thing happened to mine earlier today after I disconnected and reconnected the battery cables for routine cleaning maintenece on the battery post. Does anyone know what happened? did I blow a fuse or reset something when I disconnected and reconnected the cables?? I need to know soon, ive got to leave for work in three hours if anyone has a clue to the problem. my truck is an 04 5.4 3 valve triton FX4