1988 Ford E-Series Van charging problem continued

Tiny
TAMORAVITALE
  • MEMBER
  • 1988 FORD E-SERIES VAN
  • 7.5L
  • V8
  • AUTOMATIC
  • 70,000 MILES
The alternator model is a 7705. The field connection is an orange wire with a blue stripe, it faces up and down. It goes to the F connection on the external voltage regulator. The wire has good continuity. The stator wire is going left to right, is white with a black stripe on the alternator end and goes into a wiring harness and we do not know where it goes from there. The other 2 connections that are on the alternator, the positive connection a thicker gauge wire, black with an orange stripe, goes to celenoid and has a fusable link that is good. Tested continuity and its good. Has a ground cable on the other post coming from the alternator that is grounded on the bolt that holds in the voltage regulator. The S connection on the voltage regulator there is a green wire with a red stripe going to a wiring harness. The A connection on the voltage regulator has a light green wire with a white stripe as well as a wire that leads to the noise capacitor thats bolted to the voltage regulator. Both the green wire with white stripe and the noise copacitor are plugged into the A connection on voltage regulator and bolted to the voltage regulators bolt. About to run full field test. Please advise.
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Saturday, March 22nd, 2014 AT 12:35 PM

3 Replies

Tiny
CARADIODOC
  • EXPERT
Help me out here because this is right in the middle of when Ford was switching to a pretty decent generator design. It sounds like you have the gray voltage regulator bolted to the back of the generator with four screws. Is that right? If so, there's two additional screws near the bottom, and one has a "Ground here to test" message printed next to it. Grounding that terminal will bypass the voltage regulator. If that makes it charge wide-open, the regulator is defective and can be replaced separately. If it still doesn't charge, either the brushes are worn or you're missing the 12 volt field supply voltage that comes in on the yellow wire. The second, unmarked test terminal, which may have a plastic cap on it, must have 12 volts all the time. If that is missing, you have a blown 15 amp fuse.

If grounding the test terminal makes the generator work, you also must check if the "turn-on" circuit is working. That's the green wire and it comes from the "Battery" light on the dash. If the Battery light turns on when you turn on the ignition switch, AND it goes off if you unplug the three-wire plug at the regulator / generator, that circuit is working. If the Battery light never turns on, we have to test further to see if the bulb is burned out or there's a break in that wire. The circuit will still operate if the bulb is burned out because there's also a resistor across the bulb socket in case that happens. If the light stays on when the regulator is unplugged, that green wire is grounded, and the voltage will never appear at the regulator to tell it to turn on.
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Saturday, March 22nd, 2014 AT 1:50 PM
Tiny
TAMORAVITALE
  • MEMBER
No the voltage regulator is external. Located in front of the battery. Should the stator and field have voltage? Again this is a 1988 E250 ford club wagon. Only 70,000 miles on it. 460 engine 7.5.
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Saturday, March 22nd, 2014 AT 3:57 PM
Tiny
CARADIODOC
  • EXPERT
The stator wire will only have voltage if the generator is working, and it will be half of battery voltage, or about 6 volts. The field wire must have voltage when the ignition switch is on. Current through that circuit is what creates the magnetic "field" in the spinning rotor.

To "full-field" this system, go right to the regulator and jump the two outer terminals together, "A" and "F". "A" is the battery supply voltage from the ignition switch, and "F" is the field terminal. You can do that with or without the connector plugged in.

There is a fifth terminal on that regulator. That's the ground connection on the case. It has to be bolted to the body sheet metal to work. The original regulators used mechanical relays and limiting resistors. They needed to be grounded to regulate properly, but if they weren't, you'd still get some voltage through to the field terminal. You're going to have the electronic version. That will usually not turn on or pass any current unless it's grounded.
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Sunday, March 23rd, 2014 AT 12:28 PM

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