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A. Penland
A. Penland, Ford Senior Master Technician, ASE
Category: Ford
Satisfied Customers: 6212
Experience:  ASE Master Certified, ASE Advanced Gasoline Engine Performance
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I am having problems with my 2003 Expedition 5.4L. My

Customer Question

I am having problems with my 2003 Expedition 5.4L. My sunroof was leaking and shorted out my fuel pump relay. We got a used circuit board and replaced it. However, my alternator does not seem to be charging the battery. We have verified that their is nothing wrong with the battery or the alternator. We have hooked up a scanner and it didn't list a single error. However, we do get the charging system error message on dash.
Submitted: 1 year ago.
Category: Ford
Customer: replied 1 year ago.
Posted by JustAnswer at customer's request) Hello. I would like to request the following Expert Service(s) from you: Live Phone Call. Let me know if you need more information, or send me the service offer(s) so we can proceed.
Expert:  A. Penland replied 1 year ago.
Hello and thanks for using JustAnswer.I will try my best to help you with your question.
What is the voltage at the alternator battery post and the battery itself when the engine is running?
Customer: replied 1 year ago.
The alternator is putting out 7.5volts and the battery itself shows 12.13.
Customer: replied 1 year ago.
Alternator is putting out 7.5 without the charging leads connected.
Expert:  A. Penland replied 1 year ago.
Is the 12.3 reading at the battery taken with the engine running?
Customer: replied 1 year ago.
Expert:  A. Penland replied 1 year ago.
Check the cable between the alternator and the positive battery post.
The voltage at the alternator cable post should be identical to the reading at the battery while the engine is running.
Customer: replied 1 year ago.
The left pin hole is at 11.91, the middle is 8.75 and the right is at 7.5
Customer: replied 1 year ago.
Sorry... he said it is the 7.5 that he initially said "without the charging leads connected.
Expert:  A. Penland replied 1 year ago.
I need you to check for voltage at the post where the large cable bolts to the alternator, not the three wire connector.
Customer: replied 1 year ago.
Is someone going to call me?
Expert:  A. Penland replied 1 year ago.
Sorry I am not set up for phone calls because my phone is owned by my dealership, not me. They pay the bill.
Customer: replied 1 year ago.
Ugh! So it won't charge me? Ok, well... we have already removed and tested the alternator and battery. We have checked the continuity between battery and alternator. Problem is that the alternator is only putting out 7.5 volts when connected.We hooked up a scanner and it isn't throwing any codes. Is there anything that you can possibly think of that we have not covered. He is trying to verify that all of the grounds are clean and connected tightly.Anything that could help.
Expert:  A. Penland replied 1 year ago.
No it should not since I did not accept it.
What I do not understand is that you state that the voltage at the alternator large post is 7.5 and the battery is 12.3 with the engine running.
The PCM controls the alternator output like a voltage regulator.
The voltage should be the same at the alternator and the battery because the positive battery cable connects the two together.
Customer: replied 1 year ago.
The voltage with the cable connected to the alternator is 11.9.
Expert:  A. Penland replied 1 year ago.
Ok. SO it is 11.9 at the alternator and 12.3 at the battery with the engine running?
Customer: replied 1 year ago.
Correct
Customer: replied 1 year ago.
But that may be because we started and restarted the vehicle a couple of times.
Expert:  A. Penland replied 1 year ago.
you have a small voltage drop on the cable between the alternator and the battery positive post, but that is only .4 volts, and that is ok.
First, check fuse 2.9 in the dash fuse box. It is a 10 amp fuse. Make sure it has power on both sides of the fuse with the key turned on and the engine off.
Please let me know.
Customer: replied 1 year ago.
With the key on and engine off its 12 volts
Expert:  A. Penland replied 1 year ago.

Ok. Below is the pin point test you can follow to isolate the problem. It is quicker that us going back and forth on line. Click the link below and print it out.

Customer: replied 1 year ago.
Should B2 be with the key on or off??
Expert:  A. Penland replied 1 year ago.
Key on or off. It gets power straight from the battery.
Customer: replied 1 year ago.
It has power with key on but not off
Expert:  A. Penland replied 1 year ago.
You are testing the ORANGE/LIGHT BLUE striped wire at the alternator?
Customer: replied 1 year ago.
He just realized it was the wrong wire... we do not have any power with the key on or off... how do you repair circuit 35???
Expert:  A. Penland replied 1 year ago.

It gets power from fuse #2.9, the 10 amp fuse in the dash fuse box. If the fuse is good, go to the connector below and check for power there on Connector C270a, pin #4 in the diagram below which is on the dash fuse box.

Customer: replied 1 year ago.
Changed the fuse... still no voltage with key off --- at 3.5 with key on
Customer: replied 1 year ago.
Fuse 35 that is.
Expert:  A. Penland replied 1 year ago.

Not fuse 35, fuse 2.9. Below is a diagram of the dash fuse box.

Customer: replied 1 year ago.
Continuity between pin 4 and ground. U sure u can't call?
Expert:  A. Penland replied 1 year ago.
Unplug the alternator connector and disconnect the battery and retest. If you have a short to ground on that wire, the fuse should blow, fuse 2.9.
Customer: replied 1 year ago.
I'm confused by that.
Expert:  A. Penland replied 1 year ago.
When you are checking continuity or OHMS (resistance), you need to unplug the connectors for the circuit you are testing and make sure no battery power is connected to the circuits because that can damage the meter you are using.
Customer: replied 1 year ago.
Still has continuity... but how does it blow the fuse if the battery is not connected?
Expert:  A. Penland replied 1 year ago.
If you have a short to ground in the circuit, when the battery is connected and the connectors are plugged back in, the fuse should blow, unless there is no power to the fuse.
Customer: replied 1 year ago.
Ok... we disconnected the battery and reconnected it and then the connector. It didn't blow any fuses. (we reconnected the 207a, is that right?)Also, we tested the circuit board at location 207a. Should we be concerned with the part that plugs into the circuit board? I 9u0nders4tand you4re rea2so9n tha5t yo9u c2n2. But.... this is driving me nuts!!!!!!
Expert:  A. Penland replied 1 year ago.
It is actually connector C270a.
Sorry about the phone call. They monitor all the calls I make.
You should have power on the orange/light blue wire at the alternator which gets power from fuse 2.9.
Try this. Plug the connectors back in and disconnect the battery. Then check continuity between fuse 2.9 and the wire, orange/light blue in the connector C270a pin #4. Probe the wire into the connector from the wire side to reach the metal pin on the wire. See if you have continuity.
Customer: replied 1 year ago.
I understand!
No continuity... Didn't blow the fuse. Ugh!
Customer: replied 1 year ago.
What does that mean?
Expert:  A. Penland replied 1 year ago.
Did you open the fuse box and replace the circuit board inside it, or replace the complete fuse box assembly?
Customer: replied 1 year ago.
The complete fuse box assembly... we couldn't replace the fuel relay as it is soldered in.
Expert:  A. Penland replied 1 year ago.
Ok. Then there is a problem with that fuse box and you will need to get another one. There is an open circuit between fuse 2.9 and the orange wire.
Customer: replied 1 year ago.
Is there a sure way to test that? and does it make a difference if it is early production 2003?
Customer: replied 1 year ago.
oh... orange and light blue... lol SORRY!Can you recommend a way to test the next one before we buy it???
Expert:  A. Penland replied 1 year ago.
Check the continuity of the fuse 2.9 and the pin where the orange/light blue wire sits in the connector.
Mark the one you have now with paint to locate the pin. Any other testing you will need to have it plugged into the vehicle and use a scan tool.
Customer: replied 1 year ago.
Ok.. do I get to come back to this question later to ask more???? :)
Expert:  A. Penland replied 1 year ago.
Just reply back when you are ready. I'll get an email when you do.
I do work at a dealership during the day and getting on line to this website is a little hard. But I am on line every night when I get home from work after 6:30 PM.
Customer: replied 1 year ago.
I doubt I will be on before that time either... thank you for you help! hopefully you can help me save this vehicle!
Expert:  A. Penland replied 1 year ago.
I will try my best. Just reply back when you can.
Customer: replied 1 year ago.
Thank you!!!!
Expert:  A. Penland replied 1 year ago.
Your very welcome.

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