How to jump terminals to test external voltage regulator. this is on an ford taurus with an external regulator. There are 4 terminals, I = indicator lamp. S = stator of alternator. A = alternator or B+ of battery. F = field of alternator.

Jorge, You probably have an alternator on that truck,which means the regulator is built into it. Check the attached links,instruction and guides, Good luck

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dum b question Where my voltage regulator 1994 F250 IDI with factory turbo...

1994 ford f350 7 3 voltage regulator Google Search

where is the voltage regulator located

Running the car will drain the battery it if it's not charging ! An if your charging light is on it isn't charging ! Did you check power an grounds on the alternator ? There is a single heavier wire on the back of the alternator, this should have battery voltage ! You may want to take this to a ASE certified repair shop !
Functionality
With the ignition switch in the RUN position, voltage is applied through the warning indicator I circuit 904 (LG/RD) to the voltage regulator. This turns the regulator on, allowing current to flow from battery sense A circuit 35 (OG/LB) to the generator field coil. When the engine is started, the generator begins to generate alternating current (AC) which is internally converted to direct current (DC). This current is then supplied to the vehicle's electrical system through the output (B+) terminal of the generator.
Once the generator begins generating current, a voltage signal is taken from the generator stator and fed back to the regulator S circuit 4 (WH/BK). This voltage feedback signal (typically half the battery voltage) is used to turn off the warning indicator.
With the system functioning normally, the generator output current is determined by the voltage of the A circuit 35 (OG/LB). The A circuit 35 (OG/LB) voltage is compared to a set voltage internal to the regulator, and the regulator controls the generator field current to maintain the correct generator output.
The set voltage will vary with temperature and is typically higher in cold temperatures and lower in warm temperatures. This allows for better battery recharge in the winter and reduces the chance of overcharging in the summer.
Battery Positive Output (B+) Circuit 38 (BK/OG)
The generator output is supplied through the battery positive output (B+) terminal on the back of the generator to the battery and electrical system.
I Circuit 904 (LG/RD)
The I (ignition) circuit 904 (LG/RD) is used to turn on the voltage regulator. This circuit is powered up with the ignition switch in the RUN position. This circuit is also used to turn the charging system warning indicator on if there is a fault in the charging system operation.
A Circuit 35 (OG/LB)
The A (battery sense) circuit 35 (OG/LB) is used to sense battery voltage. This voltage is used by the regulator to determine generator output. This circuit is used to supply current to the generator field (rotor). The amount of current supplied to the rotor will determine generator output.
S Circuit 4 (WH/BK)
The S (stator) circuit 4 (WH/BK) is used to feed back a voltage signal from the generator to the regulator. This voltage is used by the regulator to turn off the charging system warning indicator. The S circuit is fed back externally on external mounted regulator generators.
Visual Inspection Chart Mechanical Electrical

• Battery case, posts, hold-down clamp, cables and connections
• Generator drive (serpentine) belt for condition and tension to make sure there is no slip between the belt and the pulley. For additional information, refer to Section 303-05 .
• Battery charge
• Generator pulley

• Battery junction box (BJB)Mega Fuse
• Battery junction box fuse:
  • 11 (20A)
• Central junction box (CJB) fuse:
  • 30 (30A)
• Circuitry
• Charging system warning indicator
• Cables

1. Check the operation of the charging system warning indicator lamp (instrument cluster). Normal operation is as follows:
   • With the ignition switch OFF, the charging system warning indicator should be OFF.
   • With the ignition switch in RUN and the engine off, the charging system warning indicator light should be on.
   • With the engine running, the charging system warning indicator light should be off.

1. Verify the battery condition. Refer to Section 414-01 .

Normal Charging System Voltages and Charging System Warning Indicator Operation Ignition Switch Position A Circuit 35 (OG/LB) S Circuit 4 (WH/BK) I Circuit 904 (LG/RD) Generator B+ Circuit 38 (BK/OG) Battery Engine to Battery Ground Charging System Warning Indicator Operation OFF 12 volts 0 volts 0 volts 12 volts 12 volts 0 volts Off RUN-engine off 12 volts 0 volts 1-3 volts 12 volts 12 volts 0 volts Illuminated RUN-engine running 13-
15 volts 1/2 battery voltage 13-
15 volts 13-
15 volts 13-
15 volts 0 volts Off

1. If the customer concern is verified after the initial inspection, refer to the Symptom Chart to determine which tests to carry out.
2. • The charging system warning indicator is on with the engine running (the system voltage does not increase)
   • Circuitry.
   • Voltage regulator.
   • Generator.
   • GO to Pinpoint Test B .
   Your whole problem is the alternator is not charging , a couple tests with a volt meter would tell you !

The Voltage regulator is mounted next to the battery. Easy to see and get to.

Before going to procedure below, lightly rap on all relays with a screwdriver handle, a sticking relay can cause all kinds of problems.
Here is the test procedure for determining battery or alternator problem after requiring a jump start. Note, requires a voltmeter [$3.50 at Harbor Freight]
1] Check battery voltage on non-start vehicle. Will probably be under 12V. Verify good clean connections, look for cracked corroded or loose terminals.
2] Jump start. Note, always have the jumper vehicle running when performing a jump start, sounds basic but I actually had a friend who argued it should not, meaning he would be jumping with less voltage & could strand both vehicles.
3] With jumper cables removed, engine running, check voltage at battery. It should be 12.8V to 13.7V. If below 12.8V the alternator or voltage regulator are suspect. If in the range, the battery is either dead, low on water or in need of a full charge. If over 14.7V the voltage regulator is not functioning properly.
4] Failing those problems, with the vehicle shut off & the doors closed, disconnect the battery ground cable, put a 12V test light between the battery negative & a known good ground. If it lights, something, like an interior or glovebox lamp, is staying on. Remove fuses 1 at a time to find the problem circuit.

the amperage of the alternator is immaterial as long as it is big enough to run the electrics of the vehicle
what is indicated here is that the new alternator required an external voltage regulator or a properly operating regulator to regulate the output voltage
battery voltage in a new battery fully charged is 13.2 volts dc and when the voltage regulator is working the controlled voltage is 14.5-14.8 volts dc
check how you wired up the alternator and have an accredited to test the charging circuit

Your alternator-mounted voltage regulator has failed. Luckily, your voltage regulator is
replaceable separately from the alternator (most voltage regulators are integral to the alternator,
and cannot be separately serviced).

Note: this works for 3.8L cobra alternators/voltage regulators only - in the 4.6L model, the
voltage regulator is an integral component of the alternator.

1999 Ford Mustang Cobra -3.8L engine

3.8L Engines

1. Disconnect the negative battery cable.

2. Remove 4 Torx® head screws holding the voltage regulator to the alternator rear housing. Remove the regulator, with the brush and terminal holder attached.

Fig. 1. The regulator and brush/terminal holder are mounted on the backside of the alternator




Fig. 2. The regulator and brush/terminal holder are secured by 4 Torx® head machine screws




Fig. 3. Hold the regulator while removing the screws to prevent the regulator from dropping out and damaging the brushes





3. Hold the regulator in one hand and pry off the cap covering the A terminal screw head with a small prybar.

4. Remove 2 Torx® head screws retaining the regulator to the brush holder. Separate the regulator from the brush holder.



Fig. 4. Slide the regulator out-the brushes will move out of the holder




Fig. 5. The brush and terminal holder can be separated from the regulator once it is removed from the alternator




=========================================================
To install:

1. Install the brush holder on the regulator with 2 retaining screws. Tighten the screws to 25-35 inch lbs. (2.8-4.0 Nm).

2. Install the cap on the head of the A terminal screw.

3. Depress the brushes into the holder and hold the brushes in position by inserting a standard size paper clip, or equivalent tool, through both the location hole in the regulator and through the holes in the brushes.

Fig. 6. When installing the regulator, press the brushes back into the housing




Fig. 7. Use a thin piece of soft material, like this plastic wire tie, to hold the brushes in position while replacing the regulator, or use a paper clip inserted in the hole





4. Install the regulator/brush holder assembly and remove the paper clip. Install the attaching screws and tighten to 20-30 inch lbs. (2.3-3.4 Nm).

5. Connect the negative battery cable.

I fixed the same problem in my 1990 Ford Taurus, it turned out to be the external voltage regulator.
I determine that my external voltage regulator had failed by testing the charging voltage across the battery while the car was idling. It should be a maximum of 15V for most batteries; mine was at 17.8V which means the voltage regulator was not regulating the voltage sent to the battery. Also when the car was parked it pulled a constant 3.0 amps (which drained my battery overnight). I was able to test for the amperage draw by just disconnecting the voltage regulator and hooking up my multimeter in series with the battery, the draw was gone.
I replaced the voltage regulator, which is a very easy fix, and I was good to go again. :)
Hope this helps someone too.

the batt has possibly expired or alt is not charging batt when running.

Either the ground cable is loose or corroded at block connection . If cleaning this does not help, change the cable!

regulator is built in to alternator, you need to have it tested. My guess is it's time for a replacement. Most parts places like autozone, will test it for you & sell you the proper one to replace it.