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Good evening,
I have tried searching the forum for an answer to my problem but I have had no luck.
I got a 2001 Excursion 7.3L that has been relatively problem free until the last 1.5 years. At that time, after I got a bit of money, I "upgraded" my batteries to AGM and my alternator to a Quickstart. I am not sure what kind of luck anyone has had with that setup, but ever since then, I have had a gremlin running through my truck. The alternator eventually failed (after warranty of course!) and Quickstart was NO HELP. In addition, I have gone through several sets of batteries because there is a parasite drain that kills the batteries after a few days of not driving it. I had the electrical system checked by a trustworthy mechanic who noted that there was an 87 mA draw after everything was shut off. He recommended that I ditch the AGM batteries. As such, I have started over with a NEW stock alternator and two fresh, standard lead acid (non-AGM) batteries. However, I still continue to have a parasite drain. In addition, the alternator does not seem to be charging the batteries. And coincidentally, the charge indicator light does not come one when I turn the ignition to run while the engine is off. I have a copy of the Ford Service Manual so I have tried to go through the entire charging system diagnosis and testing (refer to Pinpoint Test M for those following along at home) but the steps keep telling me to replace the alternators. Despite changing out multiple alternators, checking fuses and relays, I still do not have an answer to my problem. Has anyone else had this problem with the parasite drain and lack of illumination of the charge indicator light? Any thoughts on the culprit? Fuse links? PCM? Grounding issue? Random short?
Last edited by David Baumgartner; Mar 19, 2018 at 12:16 AM.
Reason: Additional Information
David, welcome to our forum ("our" includes you). I have been down this road and know a few of the bumps by heart.
Are the cables original? I am talking about battery cables + and -. I am talking about the B+ cable from the back of the alternator over to the starter relay on the fender (black w/orange stripe). I am talking about the B+ from the starter relay, across the cowl and back over to the battery junction box (black w/orange stripe). If those are still the original, 18 year old coppers in there, you need to look hard at them. Check for voltage drops like it tells you in the manual. Use a good meter. You need accuracy when doing this test. You are looking for corrosion. I had lots of corrosion in my cables when I pulled them out. The positive cable failed the voltage drop test, so I replaced it and the B+ run from the alternator. I peeled back the insulation when I had them out, and there was green powder everywhere. When you are talking about the amps required to start our trucks, it doesn't take much resistance to the flow of electricity at all to screw the system up. Shortly after finding the corrosion in my + cables, I replaced both of the battery negative cables, and I added a grounding cable from the alternator case to the negative terminal on the driver side battery. I also added a jumper to connect the two negative battery cables together at their block mounting points.
As far as the amp draw...you need to disconnect each fuse one-by-one with the DC ammeter hooked up in line with the negative battery cable. When you eliminate the draw, you have found your faulty circuit. Not too hard to do, but again...you need a good, sensitive meter.
Thank you so much for your reply. I assume everything on it is original as I bought it with about 130K miles on it. I will dive into analysis of the wiring. Again, thank you so much for taking the time to reply and help me out. I really appreciate it.
Good evening,
After doing some of the tests, I am beginning to wonder if the wiring to my alternator is reversed.
Does anyone have a picture of the wiring for the pigtail to the alternator? I am looking for the orientation of the OG/LB and LG/RD wires so please include them.
So, I think I found my problem. According to the "Shop Manual," the orientation of the two wires in the pigtail were changed from 2001 to 2002. Once I made this change, my problem was solved. Now, I have an "ABS" light on!!! Any thoughts on that one?
