I've had this message for about a week. I just installed a new (not rebuilt) alternator and still get the message. Everything else on the dash works, power windows, and power door locks also. The only thing wierd is when I plug my scanner into the OBD port it gets no response. Is this a dash issue or is it something far worse. I'm tired of trying to figure this out.
TIA

 

Have you tested your battery? That could narrow things down too if its not being fully charged then something isn't right. As well checking the output at the alternator with a multimeter while running is a good idea as well.

 

Yes had the batt load tested at the mechanics shop. They say it's good.

 

I don't know about a 2004,but on the earlier F150 I think the ODB gets its power from the cigarette lighter fuse... Check your book on the fuse page for ODB.. you might have a blown one.

 

For the benefits of others, a 12volt battery is comprised of 6 cells and each cell produces 2.1 volts. So the battery should measure to be ~12.6 volts when there is no charging from the alternator (engine off) and no major loads (lights off). The voltage will drop a little (still above 12volts) when the lights are on since charge is leaving the battery and no charge is coming back in (since the alt is off).


With the engine running and no major loads and the battery fully charged the voltage will read ~13.4 volts. Since the alternator only needs to provide a small amount of charge, the voltage above 12.6 is not much). If the battery charge is low and major loads are on (headlights), the voltage may read as high as ~14.4volts since the alt needs to send a lot of charge to the battery.

 

Ted928.....shut off the battery measures 12.5v and with it running it measures 14.3v (with nothing on). This is with a new alternator. As stated earlier mechanic load tested battery and it tested good I watched him do it and he gave me the readout from the hand held tester showing it was good.

 

I just checked my truck. Battery read 12.4V with engine off. Running voltage was 14.2 volts. That is more than I thought - I guess modern ignition systems and computers consume more power than the old cars.
So your voltage measurements seem good.


Regarding your OBD port, you likely have a bad fuse.
Check Fuse 15 5A (near passenger A-pillar).
Then check all other fuses.
Then check the three fusible links.
Then disconnect battery and reseat the three PCM connectors.

 

Yes I have come to the conclusion the problem lies in the dash. I'll most likely live with it for a while. The expense of changing one out and having it reflashed by Ford is too expensive for me right now.

 

I had a problem with my dash for years; tach would die, charging light comes on, then airbag lights, radio and windows would die.
Finally fixed it by sliding the tach motor on its contacts.

 

To expand on this, part of the problem is batteries are called "12 volt", when the reality is a fully charged maintenance-free auto start battery is actually closer to 13 volts! 12.8 volts at 70F 12.6 volts is a "standard" lead-acid open circuit resting voltage.

Tenths of a volt doesn't sound like much, however it is important. 12.0 volts may leave the driver stranded in cold weather. That's right - the difference between 100% charge and dead is less than a single volt.

Ironically many people worry about "overcharging" a battery, when the battery is probably the most abused truck component. A battery doesn't even approach a full charge until it reaches approximately two (2) volts above the resting open circuit voltage, or roughly 14.8 volts just to reach 100% full charge. This is the 70F temperature figure. Once we're talking cold temps, 15 to almost 16 volts is necessary to recharge, because of the increased internal resistance.

Next, batteries "like" to spend some time in this fully charged condition, measured in hours. Moderate outgassing is normal and desired, it circulates the electrolyte and keeps sulfation at bay. Partially discharged batteries quickly sulfate into a permanent reduction in capacity.

Vibration is part of the problem with battery life, but stationary lead acid batteries can last 20 years or longer. Not too many truck batteries last more than a few years. This is partly due to heat and vibration, but also due to abuse.

It pays to keep them charged at 100%, batteries aren't cheap anymore, not to mention alternators and other expensive gee-gaws in modern vehicles, shop labor rates they have to charge these days, etc.