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Discussion Starter · #1 ·
I'm having a charging problem.

Alternator with new voltage controller was replaced in April 2020. Battery was charging at 14v when engine was firing. No problems until last weekend.

Last weekend, while driving, I noticed that the voltage was below 12 (from a meter on a usb adapter in 12v receptacle). Uh-oh. Van eventually stalled; not enough juice to fire spark plugs. I jump with a house battery bank and got home. Charged up everything, starting battery is good (all batteries good). Holds full charge. Starter cranks, and engine turns over and continues to fire. Belt is turning alternator.

But no juice coming from alternator. Starting battery reads 12v.

I take it back to shop that had replaced the alternator/voltage controller in April 2020. Tell them, bad alternator or voltage controller.

Shop replaces the voltage controller. Shop reports that there's still no juice from the alternator (alternator is turning/engaged just fine).

Shop reports reading ground off of alternator, so no juice. They are not reading from the positive cable on the starting battery but from alternator. Reads ground.

Shop doesn't think there is a bad alternator or voltage controller. They think there is some sort of fault in a wire from ignition cluster to alternator/voltage controller that is not engaing and allowing voltage to flow from alternator.

I'm new to Ford Econolines. I don't have a shop manual yet. I'd expect the alternator/voltage controller to put out some juice when the pulley is turning unless there's a problem with alternator assembly (probably with brushes or the voltage controller circuit).

What's the deal? Why is there no juice when alternator is turning (unless there is a problem with brushes or voltage controller circuit)? Is there some solenoid or something from the ignition cluster that needs to open on the voltage regulator for voltage to flow out from alternator?

Thanks,

KAK
 

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Phoenix, AZ 85008
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Welcome to the FFO!
Based on the way you post I would guess you are not in the US. If you are in the US, take the vehicle to a Auto Zone or Oreilly's and have them do a test on the alternator. (There is not test for the electronic voltage regulator)

Attached is the charging system diagram. The connection from the ignition switch sends 12 volts to the alternator stator. If the shop wanted to prove their diagnosis, they would connect the stator. I assume they did not. If that is correct they do not want the repair work, I would not return to that shop.

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Text Diagram Floor plan Technical drawing Plan
Text Diagram Floor plan Technical drawing Plan
 

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Discussion Starter · #4 ·
Thank you for the schematic.

When you wrote, "connect the stator", did you mean attach a jump cable to the stator when the engine is running to see if the alternator starts putting out current?

Or did you mean pull the alternator and bench test it?

I took it back to this shop b/c the alternator they put in in April was under warranty, but I sorta get the feeling that they aren't trying very hard.

KAK
 

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Administrator
Phoenix, AZ 85008
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Connect the stator to + battery voltage and start the engine.
If the alternator starts charging the shop's diagnosis is correct. There are problems with the wiring from the ignition switch to the alternator.
If nothing changes the alternator or regulator are bad.
The regulator controls the alternator field. (Also needs a 12 volt signal from the ignition switch to work)

Charging system wiring is more commonly damaged at the alternator connections. And some times at the regulator. Rarely is wiring issues in the harness back to the ignition switch. That wiring is wrapped up.


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