I took a longer ride in my 68 Coronet. Out of sudden the ammeter went to full discharge and after awhile it went to full charge. Back home i changed the VR (mechanical) and put in a new 60 amp alternator. Multimeter across the batt terminals show 12,6 volts. With engine on it show around 13 volts. Now it gets confussing. Put in another VR (electrical) and voltmeter show between 12,6 - 12,8 with engine on. So no charging.
Put back in the mech. VR out of sudden ill get 15 Volt with engine on. So went to a buddy and get a brandnew elec. VR and again its not charging. Put back the mech VR (the one that puts out 15 Volt) and all it charged was between 13,2 - 13,6 Volts.

Did a field circuit resitance test (field@reg to +@bat) and the multimeter shows around 4 - 5 Volts (manual says shoould not exceed .55 volts).

Why isnt it charging with the electrical VR and why are the readings all over the place with the mechanical VR.

I should mention that i dropped the steering colum right before the drive to change the gearing box.

What to check next. Any help appreciated

sounds like a grounding problem.
I think the mechanical will pass current when the ground is bad, and can overcharge, The electronic regulator likely won't pass current if it has a bad ground.

thx for the reply. The vr has a ground wire to the engine block. what other grounds should ill check?

Under the two bolts which mount the regulator to the firewall there is still paint. I sanded the block where the ground wire goes. is that enough?

Check/trace the wires for pinched or grounded wires. I would check the area at the column first since that was where you moved things around.

I had the same problem and tried many different VR until I finally bought this one on ebay.I'm not positive it will solve your problem but it did mine.The number on my VR is 3438150 271.Part number for the VR #P-4529794
I bought it from mileoneonlineparts all one word on ebay.

thx but mine is a 1968 car. So this wont work with my alternator

with a jumper, jump 12V to the blue wire "ign" side of the reg & see if it straightens out & if so seperate/clean the bulkhead halves for a start on where the part time open is (might take some digging). If it dont straighten out with that then jump from the reg case to ground & see if that is it tho I dont think so with all the reg swapping that has taken place but it is an easy check. pull/check the alt brushes & it might be easy to swap in another alt from your stash. do check the green wire from reg to alt (& its terminals). If you get another reg FOR SURE get an electronic one. reportedly some parts store ones can take the OE electromechanical black cover for a stock appearance & Mrandy on here sells or used to sell one that is electronic with a stock black OE electromechanical cover. Your parts house has a Wells 706 (iirc) electronic (dont look stock tho if that is important). SWAG-bad reg or alt brush issue.

ill do that but do i have to disconnect tthe blue wire at ign. or place the jumper as is

Jumper as is

Across batt-terminals around 12,5 volts. With jumper connected around 13 volts. so i guess ill start with the b-head first and digg on. also measured at the alternator, that was around 13,4 @idle

Bulkhead. Pull a batt cable/seperate the bulkhead & clean the male ones with a metal mini bristle brush & the female ones with a spare male one or a new one from NAPA (725147-99 cents, might be 725145). Then spray everything clean with brake kleen. You might call an electronic repair shop or see what the guys here say for some conductivity paste to brush on, to enhance conductivity/reduce corrosion (I ain't used anything but guys swear by using something). when going back together get em barely started together so you know the terminals are lined up right then press em together.

As you probably know from the shop manual, the mechanical regulators are easy to adjust. 13.6 V isnt too of range - especially at idle, depending on temperature. So that part is easy. (Open it up, see if its dirty or something is loose or burned.)

To check the alternator output doing a full field test, it wouldn't hurt to briefly bring the engine rpms up to 1200. Voltage should go up with rpm since power into the field is not being regulated.

Might have bumped or tugged something when doing the swap.
From you last posts above, you've on the right path.

The regulator lets current through to the alternator's field. It decides how much current based on the voltage at the regulator on the blue wire. So if it sees lower voltage at that point due to resistance in the lines, it should send more current to the alternator's field. This results in a higher voltage at the alternator output than at the regulator input. (Field refers to the magnetic field generated by electricty going through the windings that are spinning).

It could have shown full discharge due to a short; but if it was showing say 10 - 15 amps discharge, that could simply have been the battery taking over because the alternator wasn't getting power in (field) OR the alternator's output couldn't connect.

When removing the bulkhead connectors, take your time. Unclip the top, the bottom and firmly work each one off. They may reclip themselves while yoiu do this. Take your time.

Remove male terminals by squeezing the barb part of the blade.

Remove the females by depressing the tab on top with a terminal removal tool or a thin screwdriver or cotter pin.


I'll attach a simplified diagram of the just the charging and headlamp circuit for a '68 - A. Your Coronet will be similar but not the same. Point is to make it easier to see the flow paths. Notice the ammeter only tells what is flowing to or from the battery.

thanks guys. will work on that later today

bulkhead cleaned but that didnt solved the problem. so im diggin on

pulled the ignition switch today with the original harness-plug. the groundwire is missing. is this right ?

Ground wire?
Nothing on he ignition switch should be a ground wire. That would be a short circuit.

ah ok. there is a male spade on that switch marked as GRD and no wire inside the connector

Would have to test the switch to see if it connects to something. But it would only be for curiosity. Shop manual shows the terminal location but doesn't show a connection. Otherwise its exactly the same as the Barracuda/dart one I posted above.

so put a wire from alt to batt plus. With everything on i get now 13,5 volts. with lights etc on it´s travels from 12,6 to 13,5 (it starts at 12,6 and travels fast to 13,5) volts. lights are now rocksteady in every rpm.

all measurments with the multimeter were alright except of the ammeter. there i onloy get readings while wiggling around. so i guess ill have to bypass the ammeter ?

I would take out the dash & visual/check on the ammeter as it might need the terminals tightened (be careful/studs need to stay isolated from ground) & might need to be replaced.