So...I have a new alternator, and two different USA made voltage regulators didn't fix the issue: https://www.oreillyauto.com/detail/.../1970/buick/skylark?q=Voltage+regulator&pos=1 That one I linked above made a weird buzzing noise. The Chinese one I tried after that wasn't noisy but it didn't fix the real issue either. The voltage goes up to 13-14 volts while cruising but drops down to 11.2 - 11.4 at idle. There is a ground strap and a ground wire attached to one of the regulator bolts. That screw would not tighten so I added a split washer so it would tighten. This shouldn't be this difficult, seems like the next step is to either upgrade or start chasing connections.
There is no ground strap connected to the rear of the head, the strap connected to one of the regulator screws is connected at the other end to the pass side upper transmission to block bolt. Doesn't look like there's anything wrong with it and neither end is loose. I believe there's supposed to be a ground strap connecting the back of the alternator to the block. If so, it isn't there, and it hasn't been for a long time; long before this current problem started. Should I add one? On that same note, do I really need to ground that radio capacitor terminal for the VR to work correctly? I have the capacitor but not the bracket that goes around it.
I could not find a ground strap at any of the open parts stores to fit the alternator stud. I checked the resistance of all four wires at the regulator connector. With the battery disconnected and the regulator plugged in, I put one test lead on each connector wire crimp and the other lead on the back of the respective spade terminal on the regulator. They all checked out fine. I checked the resistance between the mounting flange of the alternator and the transmission where the other end of the ground strap is, that was fine. Since I've had the regulator on and off a bunch of times it is getting harder to get the screws tightened. I moved the ground strap and ground wire to the only mounting bolt I can get consistently tight. Made no difference, it seems to be undercharging at idle, just over 11 volts. Anybody know how to bench test one of these regulators? I'm suspecting I have to go get new regulator number four here.
The alternator grounds through it's mounting directly to the bracket/head. No need for a ground strap. Have you looked in the Chassis Manual. They describe regulator operation, troubleshooting, and adjustment.
The regulator in there now is supposedly solid state. I disconnected the negative cable at the battery and measured 12V between the negative cable terminal and negative battery post. The plot thickens
Tomorrow I'll disconnect the Fitech handheld and see if I still get 12V with that battery cable disconnected.
Use the chineesium one and replace your battery, it has a dead cell in it from over-charging with those USA expensive regulators and is now just a matter of time before it leaves you stranded I bet.I played this game and that’s how it went on 2 of my cars over a 3-4 year period.
Door open for inside lights (that includes trunk and glove box) clock, blue tooth junk, even radio memory ? One of your tests with the Ohm meter should be to disconnect the battery and check for ANY continuity from a fuse end to ground. "Ideally" your readings should read infinity (totally open or "zero" on the meter). Take the meter and practice on stuff; its easy to get yourself "reversed", LOL. The probes are called "stabs". Hold the two stabs in the air and apart and read the meter. Thats "open", then just touch the two together and you have a circuit, hence a "short" or zero resistance. Do that to a spool of wire on each end and it may read 10,000 ohms. THAT is the resistance of the length of that particular wire. If the meter is capable (some el cheapos are not). "zero" the ohm meter before testing for "accuracy". The ohm meter part actually requires a battery inside for supply voltage. The Volt meter part depends on a source from what you are reading (the car battery for instance). Right now your really just looking for "opens and closed's". If all the stuff above is good, I'd bet on an instrument panel (or eben each individual device) ground being poor. Do the wipers "park" correctly? Anything (horns or whatever) get warm to the touch? Electrical problems can be real FM's (freaking mysteries). Good luck! ws
So the aftermarket volt gauge under the dash as well as the Fitech handheld are reading the low voltage at idle, but measuring at the battery itself reads just over 12 at idle. There must be a voltage drop somewhere.
It was stupid, earlier I went to run the test and the field terminal wasn't marked on the alternator. Once upon a time we had to replace the pigtail harness going into the alternator so the wire colors are no longer stock there. Could not quickly find on my phone a definitive diagram of the terminals on a 10DN alternator. Yes, I could have run a continuity test from the regulator plug to figure it out, but my brain just didn't go there for whatever reason. What I was able to do is this: I have this book: https://www.amazon.com/Diagnose-Automotive-Electrical-Motorbooks-Workshop/dp/0760320993 A section in there suggested disconnecting the regulator plug and with the ignition on, check for voltage at the wire that goes to the ignition switch, and the wire that goes to the battery. I took that to mean the brown and red wires, and they both checked out fine. Also it said to check for continuity to ground with the field wire. That checked out fine. I had my dad rev it to about 1500. The voltage at the battery did go up but never over about 13.9 - 14 volts.
