Re: 5587 generator issue

Posted by HH56 On 2023/6/18 11:44:35

55-56 cars were always 12v but while 55 kept the old positive ground 56 finally changed to negative ground. If your 55 is now running a negative ground and the generator was never repolarized for that change it is possible that could be the reason it is not charging.

Presuming it still has a generator and that was not changed out to an alternator during any conversion work it would not hurt to give a repolarizing a try. It may not help but done correctly, it will not hurt anything either.

To repolarize, get a short piece of decent size wire -- about 14ga will do. With key off and everything else connected as usual use the piece of wire to BRIEFLY short the BAT and ARM terminals together at the regulator. The FLD terminal must not be shorted in this procedure so make sure you are working with the BAT and ARM terminals only. A quick 2 second or so connection is all it takes to magnetically polarize the field coil pole pieces in the generator so that when the engine starts a small voltage will be produced that is enough to bring in the relay that connects the rest of the regulator and charging circuits.

If the battery ground was changed to a negative ground it is OK to leave it that way as nothing that was standard at the time is polarity sensitive -- although some regulators are labeled as positive or negative and it is still a question as to what exactly is different. There are other things that may need to change though. If wire connections were not swapped, the ammeter will read backwards and the coil will not be as efficient if it still has the + terminal going to the distributor and ground. If anything was changed to a modern solid state replacement such as the radio vibrator any solid state items may be damaged.

If the car ground is correct and repolarizing did not help then another test can be done using the FLD terminal to try and isolate the problem to the generator or regulator. If you need to do that test you will need a voltmeter and the short piece of wire.