Just changed the alt on my '72 to a '75 with square diodes and higher output. I ran a #8 wire direct from the alt to the battery. Reading other posts lead me to check grounds on the voltage reg and the ECU which are good now. Still getting pulsating dash and head lights in all RPMs. Sometimes very briefly they glow steady. Is the volt reg bad? Could the new alt be bad? I plan to check voltage per other posts here and will post later. Thanks in advance.

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'64 Valiant Conv V8
'72 Scamp /6 4bbl
'79 Adventurer SE

probably just bad diodes in the replacement alternator. When I put a rebuilt one in mine it did the same, actually took 2 alternators and 3 voltage regulators before it started functioning right lol... No quality control these days

The Piper Cherokee airplane used a Mopar setup for charging. If you really want to know your charging system in detail, including the reason for your surges, you should take the time to read this commented overview, it's the best I've seen.
http://flymall.org/aircraft/docs/Piper- ... System.pdf

Olaf

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Aspenized

Thanks Olaf. Great article. But due to all the plane refs not sure how to test for the fluctuation. Can I just run a jumper from the battery to the field winding and see if the pulsating stops? This is mentioned in the write up but not sure which field to test ... volt reg field or the one from the ign switch or both???

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'64 Valiant Conv V8
'72 Scamp /6 4bbl
'79 Adventurer SE

OK I think we are good. I ran a jumper from the field contact on the alt that has the blue wire coming from the firewall jumped directly to the battery and the pulsating stopped. So per the Plane write up provided, this means the wiring through the firewall must be too high resistance to allow the volt reg to function properly. Since the field wire must be switchable, I used a relay controlled by the firewall wire and now have a switchable direct feed from the battery to the field winding and all seems to be OK. The relay is not opening on shut down but I think that the relay is bad.

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'64 Valiant Conv V8
'72 Scamp /6 4bbl
'79 Adventurer SE

Sounds like it's time to go through the bulkhead connector and the steering column connector.

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Joshua

Excellent work!

I totally agree with Joshua, but I personally brought it one step further.
My alternator had bad diodes, but recognizing the above as one of the other sources for pulsation, is one of the reasons why I totally redesigned my underhood electrical circuit to be 'local' for charging, starting, headlights, wiper motor, heater motor, el. cooling fan and ignition. I only use the main harness to power instruments and lights and accessories inside the car, and I use return power from the main harness - like from the ignition and lightning switches, only to trigger the different underhood relays, which all are fed from the main charging circuit. All circuits are well protected with ordinary blade fuses, or Midi/Ami fuses.
http://www.slantsix.org/forum/viewtopic ... ht=#389064

It is a time consuming job (still in progress!), and it demands careful planning and exact execution safetywize, but if your wiring in general is in bad shape and you have the time to do it, my advise is to consider something similar to cover your car's needs.

If your main wire harnesses are in good shape, clean all connectors - including all ground connections, add some fuses in critical places, measure the circuits to see that there is a minimal voltage loss, and you should be fine.

Olaf

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Aspenized

Olafla, you seem pretty savvy on the electrical side. I can usually hold my own but this one has me stumped. I have run the #8 wire from the alt to the battery. I have the blue wire field winding energized by a direct wire from the battery via a 30 amp horn relay which is controlled by the blue ignition wire. When I shut down the relay sticks in the closed position. The blue control wire to the relay is dead but the contacts remain closed. If I disconnect the field wire from the battery there is a huge spark and then the line goes dead after reconnecting. Can you explain what is happening here and how to fix it? I have drafted a circuit using two more NC relays that will force the circuit open after powering down but it seems a bit odd that this relay is sticking in the first place. I have used three separate relays and all stick the same way.

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'64 Valiant Conv V8
'72 Scamp /6 4bbl
'79 Adventurer SE

Draw the schematic of the modified system and I'll bet we can figure out why the relay is not deenergizing.

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Joshua

https://www.dropbox.com/s/hv8kfl5dt3ktwip/scan.pdf

Not sure how this works but try the link above. Note the 30 amp relay drawn where the starter usually is.

Note '73 diagram and I have a '72. Not sure if this matters.

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'64 Valiant Conv V8
'72 Scamp /6 4bbl
'79 Adventurer SE

Joshua I will check the bulkhead connectors to fix this correctly but I do need to keep it rolling for now. This biggest issue is the white plastic connector at the base of the steering column is rotted and needs replacing. I'm afraid to touch it before I get a new one as it will just fall apart and I will be stuck. Thanks in advance for looking into the stuck relay.

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'64 Valiant Conv V8
'72 Scamp /6 4bbl
'79 Adventurer SE

According to the schematic and your report of the blue wire being dead when the ignition is switched off I cannot determine why the relay is not opening. If there is no voltage potential across the relay coil it will open. Maybe check the ground side of the relay coil.

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Joshua

The relay ground attaches to a mounting screw for the volt reg. There is no voltage on the blue wire or the ground with the ignition off. By chance could the amperage over the relay contacts be greater than the relay capacity making them stick together?

With the ignition off, after I break the field wire (with huge spark) and reconnect it, there is no voltage on the blue wire, the relay ground or the field wire at the alt. The relay works again when the ignition is turned on. I have been doing this for a week, resetting the system every time I park the car.

Glad this is strange to you too.

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'64 Valiant Conv V8
'72 Scamp /6 4bbl
'79 Adventurer SE

If you are using a real horn relay, that may be your issue. Change out the relay for a standard Bosch style one. Horn relays tend to have internal connections and usually only require three terminals. Battery, horn, and one to the button. They don't normally have a ground connection.

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Mattelderca
78 NYB (gone now), two S series, three old Snow Cruisers and a Doo.

I agree with mattelderca.
In general, a horn relay is provided with ground connction from the horn button. If you have a horn relay with markings 1, 2 and 3 for the connectors, 1 is power from the fuse box, 2 is ground from the horn button, 3 is to the horn(s).

Be careful with your connections, so you don't fry the diodes in the alternator, or your battery!
BTW, the photo link doesn't work for me.

Olaf

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Aspenized