VOLTAGE! help please

[86VickyLX]

Should the engine still run with battery unplugged?

Yes, it should. But you shouldn't run it with out a battery.

[1987cp]

Yes, it should. But you shouldn't run it with out a battery.

yeah, I usually figure that as long as the operating voltage is over about 14.1 Volts, it's all good.

[gadget73]

Its really bad for the computer, and not good for the alternator either. Since y'all don't have computers, its less of a big deal but its still not good for the alternator.

[Tiggie]

Okay, sorry for the delay in responding. Side terminal you say? That makes it 100 amp or a 70 amp after looking at the service manual.

So when you bypass the regulator, it charges? And how about the amp light? Does it come on ever (bypassed regulator or not)? It sounds like you have narrowed it down to something associated with the voltage regulator.
There are two different types of regulators used on these cars according to my service manual; a blue-coded and a black-coded. The black coded ones are used on cars with an amp light (like yours) and the blue coded ones are used with cars that use an amp meter. I don't know where to find the color codes, but proper black-coded regulator will have four terminals in the plug and the blue-coded will have three. Check your replacement one. Visually check to see that your plug that plugs into the regulator is not damaged

Here are some suggestions from the 1982 LTD/Marquis EVTM:
- Check Fuse Link A at Starter Relay. (Fuse Link A is a green 14-gauge wire)
- Check Alternator Belt Tension
- Check Battery Terminals and Cable Clamps
- Check for clean and tight connections on Alternator, Voltage Regulator, and Starter Relay (aka Starter Solenoid)

And from the 1982 Body/Chassis/Electrical Under Voltage Tests:
(Have car running with no accessories)
1.) If voltmeter does not indicate more than 1/2 volt above the base voltage, disconnect wiring plug from regulator and connect an ohmmeter from terminal of plug (terminal F in figure below) to ground (at battery). Meter should indicate more than 3 ohms. If less than three ohms is indicated, service grounded field circuit in wire harness or alternator.
2.) If ohm meter indicates more than 3 ohms, connect a jumper wire from A to F terminals of the plug. If system charges, the regulator or wiring is worn or damaged. Perform the Regulator I and S Circuit Tests and service the wiring or regulator as required.
3.) If the voltmeter still indicates a condition of under voltage, remove the jumper wire from the regulator plug and leave the plug disconnected from the regulator. Then connect a jumper wire to the FLD and BAT terminals on the alternator.
4.) If the voltmeter now indicates 1/2 volt or more increase above base voltage, perform the S and I Circuit Tests and as indicated service the regulator or wiring harness from the alternator to the regulator.
5.) If voltmeter still indicates under voltage, stop engine and move positive voltmeters lead to BAT terminal of the alternator.
6.) If voltmeter now indicates base volts, service the alternator. If voltmeter indicates zero volts, service the alternator to starter relay wire.

Attached is first the regulator plug pinout and second, jumper wire connections to the alternator and how to do the I and S Circuit Test, and the wiring diagram of the charging system from the EVTM.

Hope this helps!

[1987cp]

Tig-mang, your scan of schematics is a little hard to read. Does that info allow you to either confirm or deny the accuracy of my little schematic I drew up? Just curious, since complicated schematics and I don't always get along. :p

[Tiggie]

It appears to line up fairly well.

For some reason, the forum software shrunk the file, so here it is on SuperMotors where you might be able to read it:

[1987cp]

Thanks for the link. That layout is a lot nicer than in the Haynes manual, far easier to verify what's going where.