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Ask Adam Legler Your Own Question
Adam Legler
Adam Legler,
Category: Ford
Satisfied Customers: 21
Experience:  Service Advisor at Antero Automotive
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Name is ***** *****, My issue is with my 2004, F-150 Lariat,

Customer Question

Name is ***** *****, My issue is with my 2004, F-150 Lariat, 5.4L V8. I have a check charging system light, I have installed a new battery and alternator, had both check and they are good and putting out the correct voltage. However; I am still getting the check charging system indicator.
JA: Thanks. Can you give me any more details about your issue?
Customer: the check charging system indicator came on and my truck components went out. No lights, radio, gauges so I made it home and the truck would not crank. I bought a new battery, the truck started and after about 20 minutes the check charging system light came on again. I replaced the alternator with a new one, still same problem. Took the truck to a shop they tested the battery and alternator both were good. They did a load bearing test. Battery and alternator passed. however I still have the check charging system indicator.
JA: OK got it. Last thing — Ford Mechanics generally expect a deposit of about $28 to help with your type of question (you only pay if satisfied). Now I'm going to take you to a page to place a secure deposit with JustAnswer. Don't worry, this chat is saved. After that, we will finish helping you.
Submitted: 9 months ago.
Category: Ford
Expert:  Adam Legler replied 9 months ago.

Hello, my name is ***** ***** I'm here to help. I have 13 years experience as a master and advanced level technician. I saw you have a concern with your ford and it sounded very familiar to me so I'd like to offer my assistance.

First off, I'd like to ask you a couple additional questions so we can narrow down what we're fighting here. If at anytime you're not comfortable with what I'm asking please let me know and we can find a way around it.

Customer: replied 9 months ago.
Ok
Expert:  Adam Legler replied 9 months ago.

First off, does your alternator lamp flicker, or change illumination if you rev the motor up?

Next, have you had any shop/parts store check the PCM for codes? Sometime they will throw a p1246

After these questions, I may ask you to do some pinpoint testing, do you have a multimeter and how comfortable are you using it?

Thank you, I'm looking forward to helping you resolve your concern.

Customer: replied 9 months ago.
does your alternator lamp flicker, or change illumination if you rev the motor up? No, it does not, the battery light comes on and a message "Check Charging System" they do not flicker or change illumination, it is consistantNext, have you had any shop/parts store check the PCM for codes? Sometime they will throw a p1246 : No I had a shop check the battery and alternator to see if they were good and putting out the correct amps/voltage.After these questions, I may ask you to do some pinpoint testing, do you have a multimeter and how comfortable are you using it? No I do not have a multimeter, however; I do know how to use it.Thank you, ***** ***** forward to helping you resolve your concern.
Expert:  Adam Legler replied 9 months ago.

Thanks for the reply.

IF a multimeter were available, the next test would be to unplug the regulator harness from the alternator. Measure the resistance from the Battery Sense terminal to the GENCOM terminal, (on the alternator, Not the harness). Must read 950 to 1050 ohms.

If it were even borderline close to being out of range I'd suggest another alternator.

The other possibilities would be that small 2 pin connector that clips into the alternator may have a bad connection or broken wire. Again, if a multimeter was available we could test those 2 wires back to the PCM and confirm they are ok.

Just a quick edit: even though your alternator IS charging it may be possible that this connector may be damaged still, it was common in the earlier 5.4 and 4.6 motors

Your question caught my eye because I've had an experience just like yours with a bad aftermarket alternator. Even if you believe the brand is reputable, my suggestion would be to exchange it for another brand. It would be a quick rule out of one possibility.

Let me know which direction you choose to go and please feel free to ask any questions you may have. Also don't hesitate to ask for any clarification if needed. Again, I look forward to helping resolve your concern and thanks for you question

Customer: replied 9 months ago.
will I be able to reach you, anytime once I have checked the alternator with you suggested method.And if that is not the case is there another possible solution that I can check as well?
Expert:  Adam Legler replied 9 months ago.

I think that between the harness or the alternator itself that will be about as much as we can narrow the field down without some more testing equipment.

If you're thinking about making it happen this weekend I'll be more than happy to leave our chat open. I'd like to do that until I know your concern is fixed. I try to check in about every hour, so if you find anything or think of any additional questions let me know. Thanks again!

Customer: replied 9 months ago.
ok
Expert:  Adam Legler replied 9 months ago.

Hello again, hope you had a great weekend. Were you able to find anything on your truck this weekend? Again, please feel free to ask any questions you may have. I look forward to helping you resolve your issue ASAP. Thanks again!

Expert:  Adam Legler replied 9 months ago.

Sincerely ***** ***** concern has been corrected. If so, please feel free to rate me with outstanding service! If not please let me know so I can help for a speedy resolution. Thanks again

Customer: replied 8 months ago.
Adam, everything I tried has not worked. I got a multimeter and tested the battery and alternator, everything checked out for the battery. I took the alternator to a shop and they checked it and it was fine. However; it is still not charging the battery.
I believe it maybe the wiring harness but it is very difficult to fined the part. Is there anything else I can check regarding this problem?
Expert:  Adam Legler replied 8 months ago.

Defiantly an odd issue you have going on. We can actually test the harness, that will help rule out the possibility of it begins good or bad. Give me a moment to pull a wiring diagram.

Thanks again for the reply, again I look forward to helping you resolve your concern

Expert:  Adam Legler replied 8 months ago.

Attached is a wiring diagram for your pickup. Before we use it though, I'd like you to perform a couple tests with me. Again, if at anytime something is unclear or your not comfortable let me know.

Disconnect the voltage regulator (the plug, not the large cable) on the alternator. Start the engine and briefly snap the throttle to raise the RPM over 2500. The alternator should self excite and charge at a consistent roughly 13.5 V.
If that test comes back negative, the next thing I'd like you to try is to ground the body of the alternator over to the negative side of the battery. This can be done with the clamps on one circuit of a jumper cable. CAUTION: make sure everything is out of the way of the fan and belt. Also make sure you're going from the BODY or the alternator (the aluminum casing) to the negative terminal on the battery.

Finally, the last thing I would suggest is if the large battery cable that leads out from the alternator, with everything plugged in test voltage right there and see if it differs from what your reading at the battery. Also if your multimeter has sharp probes try poking at different spots along the harness, same wire of course, seeing if the voltage differs.

In addition. Check that wire diagram attached, there are disable links in that charging circuit. They act like inline fuses that are pieces of wire. Checking them is a matter of confirming continuity in front and behind them. Let me know your results of the above tests. I look forward to helping!

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