Couple of weeks ago ,on the way to work I noticed my voltage gauge was going down so I turned around and got her home , took taxi to work , ,got home from work at the end of the week (truck driver) , gave it a boost and all was good . yesterday it done the same thing , so went and bought a new alternator , put it on and today it done the same . Called the dealer and they said to have it put on the computer 115 bucks , but off the top of his head he thought it might be the ecm . ???? it's a 2004 f150 4.6 . any one else run accross something simular. I thought about the voltage reg. but to have the same thing happen on a new one seemed pretty unlikely but could still be possible . Now hopefully I can return the new one tomorrow (315.00 bucks ) thanks

 

Have you checked to see if there is a fuse in the system (or more likely a fuseable link) that is burned? I believe they usually use a fuseable link in the alternator line but can't say for positive on an '04. The guage would still read but it would only be reading your battery voltage since the alt. output wouldn't be getting to the battery. IF it has a fuseable link, they sometimes bury them so they're not really easy to find. You'd probably need a schematic

 

Thanks code58 , I bought a new battery on Sunday and tonight or tomorrow I;m going to go for a good drive with the lights and heater on to see if it stays charged , (taking my phone with me too LOL) ,

 

Well that didn,t work , I guess its time for the shop to have a look at it , sure hope its not a computer ,

 

computer was good ,wiring good , turns out that ford used 4 different alernators in 2003/2004 , buy the wrong one it won't charge . what ticked me off the most was that when enquiring at the Ford dealer in London they didn't give out this info , since I don't live or work near there ,I decided to take to a local shop , and the local GM dealer offered up the info , thanks ford