1964 C10, 10DN Alternator FIELD wire

[ClemSmith]

1964 C10 10DN Alternator FIELD excite wiring.

64 C10 V8 with 10DN alternator and external voltage regulator.
Alternator and regulator test good (14.6v) at NAPA shop.

Where does alternator FIELD excite wire (dark blue from regulator) attach to alternator?

Looking at alternator plug from the rear:
Which terminal (12 oclock, 2 wire plug) is Field wire (Dark Blue wire from regulator #F)? Left (driver) or right (passenger)?

Which terminal is R (White wire from regulator #2)?

Tried search, electrical threads, and find various info. Searched interweb and found conflicting info/drawings.

Wired as per 3844000 V8 Truck Wiring, Pg 377 in Assembly Manual,
Dark Blue wire to left F terminal, White wire to right R terminal.

Alternator has vertical terminals in top 2 wire plug (10DN).
B terminal is Red bat wire from horn relay. G is ground lug.
Alternator case is NOT marked R, F or 1, 2 etc

Thanks, Clem

[ClemSmith]

Could someone with 1964 original type 10DN alternator with external regulator please look at back of alternator and verify position of BLUE wire?

[ray_mcavoy]

Originally Posted by ClemSmith

Wired as per 3844000 V8 Truck Wiring, Pg 377 in Assembly Manual,
Dark Blue wire to left F terminal, White wire to right R terminal.

I don't think the orientation of the R and F terminals shown on the wiring diagram is necessarily intended to match up with the physical orientation of the terminals on the alternator. With a 10DN mounted on the engine (with the plug near the top), the F terminal is on the right (as viewed from the driver seat), and the R terminal is on the left.

Originally Posted by ClemSmith

Alternator has vertical terminals in top 2 wire plug (10DN).
B terminal is Red bat wire from horn relay. G is ground lug.
Alternator case is NOT marked R, F or 1, 2 etc

The unmarked case could be an aftermarket replacement that was installed during a rebuild. Or possibly a case that's been through the rebuild process a few times and the markings have been blasted away.

Here is a pic I found on the net showing a 10DN with the original terminal markings:


The dark blue wire should run from the F terminal on the external regulator to the F terminal on the alternator. And the white wire should run from the 2 terminal on the regulator to the R terminal on the alternator.

[ClemSmith]

Thank you. That's what I needed to know....and what I deduced.

No idea where this alternator came from, or how many times it was rebuilt, where.
Truck wiring under hood was "hokey" at best.

Used to fighter aircraft wiring schematics where orientation of terminals is correct...and critical....or things fry.

Don't rewire a Chevrolet by the factory drawing, eh?

Thanks for the help.
Clem

[ray_mcavoy]

You're welcome!

Yeah, unfortunately, you can't always go by the physical orientation of the terminals as shown on the wiring diagrams. Terminal numbering or lettering (when present) is usually correct though. And in this case with the alternator, I think it might be an error on the 1964 diagram because the 65 & 66 diagrams in the assembly manual do show the F & R terminals in the correct orientation.

[ClemSmith]

Thanks again, really helps to have someone knowledgeable and helpful looking after me.

No telling why this alternator is unmarked.

Alternator now works…but putting out constant 17.8 vDC…..my voltage regulator must be dead or not sensing voltage….its also of unknown age/origin.

Is the White 20ga wire from Alternator R terminal to Regulator #2 the regulator voltage sensing wire?

I'd hate to plug in new regulator and burn it up.

Tracing power wire by wire under hood...but counting on wiring diagram to be correct.

[ray_mcavoy]

The voltage sensing wire is the red one connected to the regulator terminal #3. It's a fairly short wire that just runs over to the nearby horn relay and connects to one of the 2 screw terminals. Those 2 screw terminals on the horn relay are connected together and serve as a main power distribution point where the heavier gauge red wires from the alternator output, battery charge wire, and main cab feed wire all join together.

[ClemSmith]

Great.

What is the function of the White 20ga wire from Alternator R terminal to Regulator #2.

Rang out the Horn Relay 12+ wires. good, all new. ( Should have bought whole new harness).

Any way to test the regulator on truck, running?

Old school would have me disconnect regulator plug and (for short period) jump #3 (Red 12vDC) to F (Blue, alternator Field)...watch for arc and have alternator voltage up.

Who sells a GOOD external voltage regulator?

[ray_mcavoy]

The white wire running from the alternator R terminal to the regulator #2 terminal connects to a relay inside the regulator that operates the "GEN" light on the dash.

It's been a while since I've done any testing/troubleshooting on one of these externally regulated systems, but I believe disconnecting the regulator plug and installing a temporary jumper wire between the F and #3 terminals (to full-field the alternator) is basically how they show testing the alternator in most of the old service manuals. I don't have a manual handy at the moment, but I'm pretty sure they also show the location of the adjustment screw (inside the regulator) and describe the voltage adjustment procedure. And I seem to recall them saying something along the lines of replacing the regulator if adjusting it doesn't bring the voltage to within specifications.

Wells makes a good solid state external regulator that fits right in place of the old electro-mechanical style regulator. And if you're doing a stock restoration, it will accept the original Delco-Remy cover.

[ClemSmith]

Thanks again Ray,

I recall similar troubleshooting from my 1972 college auto shop training.
Have an old Motors manual somewhere.

Have more experience with WWII Dodges and Indian motorcycles (6v adjustable generator/regulator) and A-10, F-15 aircraft.

Not doing a factory correct restoration....or show quality….just trying to keep good original truck as stock appearing to use as occasional good driver.

This regulator is rivet sealed. No external adjustment or access to internals.

I'll replace regulator.

Thanks for all your help,
Clem

[rvrfoot]

Nice truck.

[ClemSmith]

Thanks. Looks nice, paid $5000.....it was sitting almost derelict after owner passed....now need it to run nice....almost there.

Needed a long bed to haul bikes and V8 to pull 1964 Airstream.

[LostMy65]

I was stupid and didn't take pictures.
What color wire goes where? I know the big red wire goes to the BAT terminal.

[LostMy65]

Actually,
I think this post answers my question.

Originally Posted by ray_mcavoy

......Clip......
original terminal markings:


The dark blue wire should run from the F terminal on the external regulator to the F terminal on the alternator. And the white wire should run from the 2 terminal on the regulator to the R terminal on the alternator.