jcat

1984 Berlinetta H vin .. 305cu 4 barrel . yesterday started her up and after a few min I hear a buzz sound under the dash . then I rev engine and choke light comes on .. doing all the troubleshooting the problem got worse. choke light on at idle , choke heater relay buzzes.. on the choke heater relay
lt blu wire 3-5 volts same on the choke heater at carb.. choke resistance 23 ohms. choke fuse replaced 20Amp volts on the heater relay coil 14.7 volts on the fuse to the relay , and the other coil connection measure 16.5volts which goes to the alternator #1 connector .brown wire.
disconnected the alternator connector turned key on engine off got 12.5 volts battery volts so when the connector is connected to alternator engine on the volts rise to 16.5 volts..so that is why that heater choke relay is not closing to put power to the choke heater.

the alternator has 2 wires on plug #2 battery #1 goes to choke heater relay coil. I measured the brown wire #1 at alternator and the volts 16.5DC..then measure the volts on #2 that goes to battery 14.7 volts.

when I rev it the battery volts light comes on so the gauge indicated much higher voltage.

I replaced the alt voltage reg same deal and same volts ..so what do you think causes the alternator to put out too much voltage and connector #1 to have 16.5 volts ? this all happened yesterday so must be on electrical component that failed ..

jcat

so with other searching on why this is occurring voltage too high from alternator .. so It may be the rotor is shorted lower ohms. the rotor brush rings should read 2.4 / 3.5 ohms. if too low that will cause the voltage regulator to not control the voltage at the lower correct amount.

I will check this soon and most likely get another alternator to fix it.

jcat

after testing this alternator to be sure it is not a wiring/component issue , I took it to the store to have it tested . the stator windings are bad .. volt reg/diodes good.. so that is why it did react so variable as the windings as they heated up , changed how this , choke light reacted.

also on the brown wire at alternator I got 4volts ac which is why that choke relay was buzzing .. stator caused that also

jcat

problem solved . I took apart the alternator power diodes 6 and there was some green corrosion on the surface conductors .. took a bit of time to not damage the mounting structure of these diodes. no buzzing voltage 14.5volts DC and no ac volts on the #1 brown wire that is on the alt connector that goes back to the choke relay coil .. put headlights on voltage held solid and alt put out 24 amps...

might help someone that has the ability to troubleshoot electrical devices .
alternator test racks not up to it !