I have done a motor exchange in my 2000 Explorer 4.0L OHV. The older alternator was failed so I bought a new one. The battery light is on which tells me the alternator is not sending a charge to the battery. The battery is tested and good. I used my volt meter to check the output voltage from the alternator and it is not sending a charge. I suspect it is related to the voltage regulator but I can't find any wires that are damaged anywhere on the harness. I was careful not to pinch or stree anything associated with the wiring harness. I went thoroughly through both fuse boxes under hood and inside and everything tested ok. Why would the alternator not charge the battery if everything else tests OK? I've bought a second alternator and the same result. No charging the battery. Please help.
I f your Alternator is good, I suggest review the Voltage Regulator.
2000 Ford Truck Explorer 4WD 4.0L EFI OHV 6cyl
Voltage Regulator - AdjustmentsThe voltage regulator is an electronic and is contained internally within the alternator. No adjustment is possible.
The voltage regulator is an internal component of the alternator and cannot be serviced separately.
Removal & Installation
To install:
The voltage regulator is an internal component of the alternator and cannot be serviced separately.
Alternator - Removal & Installing
4.0L OHV & 5.0L Engines
Negative battery cable
Air cleaner outlet tube
Drive belt
Electrical connectors from the alternator
A/C manifold and tube bracket aside, 5.0L engine only
Wiring harness to alternator push pin
Alternator
To install:
Alternator. Torque the bolts to 40 ft. lbs. (55 Nm).
Push pin for the alternator wiring harness
A/C manifold and tube bracket, 5.0L engine only. Torque the bolt to 106 inch lbs. (12 Nm).
Electrical connectors to the alternator
Drive belt
Air cleaner outlet tube
Negative battery cable
Fig. Alternator mounting-4.6L engine
To install:
I hope help you woth this. Good luck.
Explorer models newer than 1995 have integral voltage regulators. If an
integral voltage regulator isn't working properly, the owner has to
replace the entire alternator.
From Check out the battery cables. Make sure that they are connected good
and not corroded or damaged. Also check the connections at the
alternator.
From other Ford Owners comments:
- I had a 97 Expedition with a battery indicator, 12.4 volts at
the battery with the engine off and 11.6v with the engine running.
Replaced the alternator and then had 11.9 v with the engine running.
Checked the alternator fuses on the firewall and found the 175a
alternator output fuse blown. Replaced the fuse and voltage then read
14.3 with the engine running. Not sure if the fuse was blown before the
alternator was replaced or not as I never thought a 175a fuse could
blow without fireworks.
2 cents: Fuse...
Also check for defective replacement alternator, alternator rebuilt
with incorrect regulator, damaged instrument panel cluster, or damaged
or poorly connected wiring.
Rocky_B Sounds like a dead battery cell. 1) Engine OFF - A servicable
battery will show 12.5 volts at the terminals, anything less and you
have dead or dying cells - Replace the battery. 2) Engine RUNNING - A
good alternator should put out 14volts or more. 13-14volts=weak
alternator; If voltage at the terminals is the same or lower after
starting, your alternator might not be putting out anything or you have
bad diode pairs in the voltage regulator. With most newer models the
voltage regulator is attached to the alternator, so you replace both.
If the voltage regulator is not attached to the alternator, you still
want to replace both as voltage regulators tend to become mated to the
old alternator's output over time. replacing just the alternator could
cause the voltage regulator to fail.
Also can review the wiring diagrams (clic in the pic):
Good luck.
its a brand new alternor , plus i had it rechecked, anybody with some real world answers, not the the backyard mechanic rubbish
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The voltage regulator is attached to the alternator and this is the 2nd alternator from two different stores and I have the same result. What else could cause it. Is there a troubleshooting technique that I'm missing. I have verified the ground is true, I do have minimal resistance when I ohm the ground plug of the alternator and and alternator body. When I check the volts from the alternator output post to the battery it is at 1.9 volts with the key off. I also have tried running a direct 8 guage wire from the charging post to the battery and still no output from the alternator. The only thing I'm not sure about is the three wire plug that is connected to the alternator and the purpose of those wires and what effect could something else have that those wires are associated with. The previous alternator that I returned also tested good. The battery holds a great charge and doesn't degrade while sitting.
What actually controls the voltage regulator that tells it to charge or not? I think this is the most likely issue but I'm finding no where anything specified as the voltage regulator control if you will.
I have the problem resolved. It was the 175 amp fuse. The diagram you provided shows it being an integral part of the charging system and I didn't have any continuity on that fuse. $5.13 later it charges at 14.2v. I have read several forums in the past three days and not one mention of the 175 amp fuse was posted. I hope to find some of those and reply to my findings to share with others who have the frustration of buying alternators and batteries and not even having a clue the 175A fuse could be the problem. Thank you for your assistance.
I have the problem resolved. It was the 175 amp fuse. The diagram you provided shows it being an integral part of the charging system and I didn't have any continuity on that fuse. $5.13 later it charges at 14.2v. I have read several forums in the past three days and not one mention of the 175 amp fuse was posted. I hope to find some of those and reply to my findings to share with others who have the frustration of buying alternators and batteries and not even having a clue the 175A fuse could be the problem. Thank you for your assistance.
i replaced all fuses including the 175 amp fuse wire harness,alternator, grond wires battery
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