Originally Posted by T-Bird Lover
There's a lot of wrong info freely given all over the net. I would use sound troubleshooting techniques and let the tool tell me where the problem is. Draining a 50 amp/hr battery in fifteen minutes usually makes wires hot.
'56 was the first year Thunderbirds used 12 volts. Have you got a 12 volt test light? If not, buy a cheap one or make it yourself from a dash light bulb and a lamp holder. DO NOT use an LED.
Simply pull one of your battery cables off and connect the test light between the battery cable (you just took off) and the battery post it came from. If the light shines you have a drain. If it doesn't shine, your battery may have an internal short.
To troubleshoot the drain, disconnect the B wire from your voltage regulator. If the light goes off, put the B wire back on and lift the other two (generator) wires off your voltage regulator. If it still stays on, your regulator is shorted to ground. Open it and inspect the relays the normally open contact on the far RH side may be stuck together, a coil may be shorted or the resistors may be bad.
If your light stays on when pulling the B wire off your regulator, put it back on and go to the starter solenoid. Disconnect the battery wires from that post. All the wires to your dash, windows, seats and headlights start here. If the light goes off when you pull the wires off the starter solenoid, follow the yellow wire. Make sure it isn't frayed and arcing anywhere. This wire has no fuse.
Do that and get back with us. - Dave