2004 expedition 2.4L check charging system message

[stamp11127]

The pcm may not be getting the correct voltage on the sense wire it uses to determine if the alternator is charging.
Check for voltage on pin 3, brown wire of the connector on the alternator. You should have battery voltage with the engine off.

 

[Jeremy Martin]

Thanks I will check that tomorow after work. I get off early and should have some time to check it before it gets dark.

 

[stamp11127]

Post the results from Advances test or test it yourself by reading the charging voltage on the battery posts with the electrical system heavily loaded - engine running @1500rpm. The intent is to get the voltage regulator to "full field" the field coil and produce max output.

I don't take the readings from the battery terminals - at the post is more accurate since it is reading through all the connections in that circuit.

You can load the system with blower motors on high and ac on. The more things on the better.

Charging voltage should run 13.5 - 14.5 volts.

 

[Jeremy Martin]

Advance Auto diagnostic test results: (I don't have a way to scan the printout so I'm just typing everything out - no way to show the little graph printouts.

"Starter Test"
"Results Cranking Normal"
"Voltage 10.56V"
"Amps: 0.0a"
"Time: 875mS"

"Charging System Test:"
"Results No Problems"
"No load: 13.99V"
"--.--A"
"Loaded: 13.87V"
"--.--A"
"Ripple: 42mV"
"Charging System Output Test Normal"

I will try the test you advised about this afternoon after work. I will post a status next week (hopefully). Internet connection at home is down again and AT&T cant fix it until sometime next week - so I'm using the internet connection at work.

 

[stamp11127]

Seeing that their tester has a field for amps in the results, this test only tells you half the story. How much was the system loaded to? Beats me.

The test I outlined earlier you will have a ballpark amp load on the system. Figure each blower motor will pull close to 20amps, high beams another 20 so both blowers and headlights will pull close to 60amps.
If you read this before doing the test monitor the charging voltage as you turn each component on and record the readings. Turn them off and also monitor the charging voltage as it charges the battery. You should see a voltage change as it charges back up. Usually it is close to one volt difference.

 

[Jeremy Martin]

Finally got the issue solved. We visited the inlaws for thanksgiving the father inlaw took our Expedition to his mechanic. He replaced the brand new altenator that I had already installed with another new one. It seemed to solve the problem for about 4 1/2 hours and the issue reappeared again only worse with a constant alarming and realarming chime every couple of seconds that just wouldn't STOP!

So the father inlaw took it back to his mechanic this morning before we made the 5 hour drive home and he got a differant brand of altenator. This time it fixed the issue. Apparently the previous 2 altenators were rebuilt altenators but the 3rd was a completely new one. The mechanic said that he's seen a lot of the rebuilt altenators do this. Not just Ford but all brands.

This is the mechanics opinion but he's been a mechanic for over 30 years so he should know a thing or two.

He said that "all the newer cars with computers are very particular with the fluxuating voltages and amperages and more-so than the older non-computer controlled cars. The altenator has got to produce exactly what the pcm wants to see or it dosent like it. " He also said that many of the rebuilts he's messed with dont always get rebuilt to the exacting specs they should be.'

I asked him why the stores tester said the first replacement altenator was good. He said that the store had lied and didnt want to warranty it, or the store clerk had no ideal how to read the results or test it properly. He has his own machine to test them and it failed his tester.

How do I go about marking this as "Solved"?