I bought a 4.6 06 Explorer and have the generator red warning indicator come about 20 seconds after starting. I have a reset button which clears out the warning light, but then it comes back after 20 minutes of driving. I'll reset it again, goes off, and within about the same period of time and comes back on.

It has a new battery when I bought it 3 months ago.
Brand new PCM installed within last month by a transmission shop who replaced the transmission.
Put a scanner and code p0620.
Scanner reads the battery voltage is around 13 volts and the generator output at 13.2 volts when driving. Been like this for 400 miles, so not running off battery and generator working fine.
Just replaced the alternator and replaced the pigtail connector and I had tested at parst store where I bought the generator and they said ti is working perfectly.
Checked all the engine grounds to chassis and all looks good.

Any idea where to check next?

 

13V isn't very good. Should be 14- 14.6 New alternator? serp belt and tensioner. although the latter would be making noise.

 

Actually the generator is putting out a solid 14 volts when charging, so good there. When we bought the car the generator looked almost brand new, but replaced generator thinking it may have been bad since we bought just a few month ago and did not know the history.

 

Help us understand the above versus your comment in the first post of, "the generator output at 13.2 volts when driving. Been like this for 400 miles, so not running off battery and generator working fine." If you're measuring 13.2 volts when driving, that is low. If you're getting 13.8 - 14.4 VDC as mentioned in your more recent post, that seems reasonable. But your two statements seem to contradict one another.

-Rod

 

Wanted to clarify on the first post. Those readings were inaccurate and disregard the voltages.

Bought this car a couple months ago and had the transmission replaced. I had only driven it for two days and no problem with tnot generator warning light coming on. It was after the trans replacement that the the generator light issue started

When trans shop replaced the trans, they also replaced the PCM. They had the truck for about 5 weeks as there was problem with aftermarket alarm system and an aftermarket remote starting system causing the car not to start as it had a problem with the Ford antitheft system Their solution was to remove all aftermarket systems, recode the keys, and replace the PCM. That worked, but thats when the light started. They replaced the PCM again and the generator light still persists. The trans shop said the generator problem is not their problem and probably something else.

My problem is that the red generator light comes after a few seconds after startup. I press the reset button and won't come back on for ten to twenty minutes. It appears that they system in working normally, just the computer thinks the generator is not putting out any voltage. Wondering is maybe its the wire coming off the generator and into the PCM.

Here's what I know and have replaced:

PCM is brand new
Battery is brand new
Battery voltage with key off is about 12.5 volts at the terminals. When engine is started up the generator voltage at the battery reads around 14.58 volts at the battery terminals.
Replaced pigtail coming our of generator as it looked frayed. Did not solve problem.
Checked belts and is not slipping.

Generator is brand new and correct one for vehicle. Had it tested after installed and took to the auto parts store to have them test it and they said it was working within specs. I think the old generator was charging fine, but replaced thinking it may have been the problem causing the light to come on.

Any suggestions would be appreciated.

Anyone have a wiring diagram for the PCM on a 2006 Explorer Eddie Bauer 4.6? Specifically what terminal the wire from the generator is?