2.9L & 3.0L V6 Tech General discussion of 2.9L and 3.0L V6 Ford Ranger engines.

3.0 alternator issues

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Old 06-08-2018
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3.0 alternator issues

3.0 ranger edge.
battery light came on, shortly after followed by abs and park brake light, soon after, guages went haywire and truck shut off.
Now I'm not completely dense, and have done a **** ton of troubleshooting, and am stumped. Did the obvious and replaced battery and alternator. When problem persisted, I started doing load voltage tests.
Load tested battery, it's fine. Tested ground to alternator casing (0.08) should be fine, positive to bat (alternator terminal) was a little higher than I would like at 0.17, but should be fine. (btw I tested those same connections at a later time and ended up with better results, but not sure which was load tested and which was not, the good results or bad) which brings me to my next problem.
When I'm trying to get the vehicle home, it seems to do, ok, when I'm on the gas. At a red light, or when I idle, is when lights start to pop up and it acts up before dying.
Also, I checked the fusable links between the alternator and voltage regulator, checked it with continuity, and their fine .
Ground wire from battery to engine block is pretty bad .chopped about 6 inches to throw on new clamps, and still got bad corosion.
So it goes without saying that when I test the voltage between battery terminals while the vehicle is running, it should be at about 14.2 .but it's not. It's only reading whatever the battery decides to put out.
I'm stumped. I truly hope someone can help shine some light on the situation. Thanks in advance.
 
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Old 06-08-2018
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Welcome to the forum

What year is your 3.0l Ranger?
They used 3.0l from 1991 to 2012, so a few different charging setups.

2003 and earlier were all pretty much the same

key OFF
test battery voltage, say it is 12.5v
Test alternator case to B+(larger terminal on back of alternator), should be same 12.5v
Pull off 3 wire voltage regulator connector
Test yellow wire, still using alternators case as ground, should be 12.5v

Test Green wire, should be 0volt
Turn key ON
Test Green wire, should be 12.5v now, this is the ON/OFF switch for alternator, also the Battery Light wire.

If all 3 wires test OK, then start engine.
Test battery voltage, should be above 14v but under 15v
If not replace alternator, new or not it is bad if the above 3 wires tested as OK

Don't over think charging systems they are very very simple
 
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