Alternator Field Wire Shield or Not

I saw a few old posts on here where people had issues with unstable alternator outputs and replacing the field wire supposedly fixed it.

Now, I haven't tested mine yet, but before I seal everything up, what is the recommendation on shielding the alternator field wire?

I called PlanePower, and they said they do not have a recommendation - the factory harness is not shielded, and apparently in the turntables for the rv-14 it is unshielded as well. Additionally, PlanePower does not sell the crimp terminals.

The standard routing puts the field wire next to the alternator output for ~3 feet.

Anyone have issues with this or any suggestions? If replacing it, what is the part number for the crimp terminal in the alternator connector?

Unshielded

Not necessary.

Field current (DC) is supplied to the alternator. Shielding wouldn't serve any purpose.

If it's an audio (AC) circuit, RF (AC) circuit, etc. then it's necessary to shield the current SOURCE (not SINK) end of the circuit.

The standard harness is missing the rubber isolation/environmental seals that SHOULD be installed (I am referring to the grey-oval 3 pin connector). You can apply some sensor safe RTV, E6000, etc. into the wire side of the cavity to provide support for the wire. Or, you can find a replacement connector, pins, rubber boots on Amazon and elsewhere... https://www.amazon.com/Connector-3-Way-Alternator-Toyota-90980-11349/dp/B07JBKJT5T


B

That's a good explanation. It does make me consider alternator failure then. As I understand one mode of failure is a bad diode which causes AC ripple on the alternator output. Then if it's bundled with the field wire what effect would that have? Does it matter?

Thanks for your speedy reply and great information! I would definitely have missed the gaskets on the connector.

McStevens said:

That's a good explanation. It does make me consider alternator failure then. As I understand one mode of failure is a bad diode which causes AC ripple on the alternator output. Then if it's bundled with the field wire what effect would that have? Does it matter?

Click to expand...

Nope, if one or more of the diodes fail, you'll see a progressively larger AC ripple on the DC output from the alternator. That ripple translates into "whine" which shows up everywhere: radio transmissions - sent and received, Some lights will flicker, etc. No amount of shielding will suppress this as it's on the "B" terminal output from the alternator.

Agreed, no shield required.

If you start getting strange voltage fluctuations or over-voltage trips first thing to check is the field wire connector on the alternator itself. Engine vibrations can lead to a loose connector or frayed wire which then can cause erratic behavior.