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I have a 88 F350 4x4 with 7.5 and auto transmission. I am having a charging issue. Changed alternator and battery as well as double checking all wire connections. I do have this loose wire that I cannot seem to find on any wiring diagram. Any thoughts?
Basically that type of terminal is no bueno, they are OK in an emergency situation for temporary use.
Testing alternator output is always done under load, with A/C on full blast, headlights on HI, stereo etc. Run up the RPM to about 2500 and then measure at the battery posts. Normal charging voltage at idle is 13.8 to 14.3 at 80° F.
It wouldn't be the first time a "new" alternator was defective.
At idle with all of the items you mentioned on, I am at 12.89 volts at the terminals. Any idea what that extra wire may be? I have had the truck about a month and that wire was like that when I got it.
12.89 at idle is too low, although charging voltage will sag a bit under load with accessories running. This is why it's checked at 2000+ RPM, it simulates highway cruising. It's very important that cables and ground connections are clean and tight, and the drive belts are not loose. Original factory battery and ground cables should be replaced at some point even if they look OK. 30+ years is a long time for ground cables.
I have a 88 F350 4x4 with 7.5 and auto transmission. I am having a charging issue. Changed alternator and battery as well as double checking all wire connections. I do have this loose wire that I cannot seem to find on any wiring diagram. Any thoughts?
Thank you.
I would trace where that plug goes to. Seems odd to have 2 negative/ground cables like that. Is it possible that wire goes to something else?
That wire also goes under the clamp on the NEG battery post.
The connector in the photo is C104.
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Subford may have nailed it here upon reflection. Clean the wires, check the color coding on them and follow his instructions. I did not read this post as thoroughly as I should have, and may have spoke to soon.
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