Electrical gremlins…bad alternator?

[sleepycruiser]

Been working through some gremlins this week on my ‘64.

I noticed my blinkers and horn were not working. Re-grounded the rear lights and the blinkers started working. Mess with the relay for the horn and got those working for a second.

I noticed yesterday as I was checking everything that my battery was at 12v and the alternator was only at 12.5v. I drop to the store…has an aftermarket gauge and it was reading below 10v while I was sitting at a red light..got home and the battery and alternator tested at 9.5v while running!!

Today I checked the grounds in the engine bay (starter, alternator, battery ground, horn ground) and I took the alternator out and cleaned any point it has contact with the FJ. I had to jump it off and then when I unhooked it the battery and alternator were both at 12-12.5v. The alternator case is reading 8mv instead of 0. So I have a bad ground somewhere. I am ordering a tap and die set today and will be going through every ground point I can find, but does it sound like the alternator is going as well?

I’ll also add the blinkers and horn will only consistently work when the jumper cables are attached to the other vehicle… even if it is running the will work at first and then not work…almost like they are starting at full blast and then slowly degrading.

I’m sure this could be 1,000 things and someone did post some great tips in another thread about grounds. I’m just wondering if I should go ahead and change the alternator.

 

[charliemeyer007]

Does it have an external voltage regulator? They can be adjustable. Charging voltage should be at least 13.5 to 14.4 IMHO. When my alternator goes I doing a one wire GM 105 to 120 A to replace the OEM 30A

 

[sleepycruiser]

This? How is it adjusted?

 

[charliemeyer007]

There was a whole write up somewhere here in the last few weeks. Start with take the cover off and use a piece of crocus cloth the clean the contacts. Do the outside ones too. Unhook the battery first.

 

[sleepycruiser]

Thanks. I took it apart and it all looks ok. I did clean the corrosion off the interior part of the ignition tan, but don’t think that would lead to the overall issue. I did clean the exterior contacts earlier when messing with the alternator.

 

[charliemeyer007]

It does "look" clean. It never hurts to have some spare parts, get a new alternator and voltage regulator and keep the old ones as a spare. In the alternator the contact brushes for the slip rigs could be worn out or the springs went bad, bad/weak diode.... Have you load tested the battery.

 

[sleepycruiser]

It does "look" clean. It never hurts to have some spare parts, get a new alternator and voltage regulator and keep the old ones as a spare. In the alternator the contact brushes for the slip rigs could be worn out or the springs went bad, bad/weak diode.... Have you load tested the battery.

I have not yet. I tried to crank it after taking the regulator out and the battery didn’t seem to want to crank it. I’ll likely take the alternator and battery out and have them both tested.

My concern is would the 8.0mv on the alternator case kill a new alternator or battery?

I’ll need to research to see what the recommended alternator is…I assume OEM.

 

[sleepycruiser]

I might have figured something out…well at least found an issue. I have a switch on the dash above the key. It has 2 wires coming off of it, which are tied together…one is disconnected..hanging there. The other wire coming off that switch goes to the red wire on the voltage regulator, which should go to ‘IG’ on the voltage regulator. So the ignition isn’t tied to the voltage regulator, Where on the ignition switch should that wire from the voltage regulator commect? I wonder why a switch was wired to it to start with.

Edit: Based on the wiring diagram it should be going from IG to the WB wire on the ignition. Fingers crossed.

 

[sleepycruiser]

Hooked the IG wire to the WB portion of the ignition up and didn’t seem to make a difference, actually it seemed a little harder to get the starter to engage. When I have my jumper cables on the alternator is at 13.3v as is the battery. I’m going to take the alternator in to get tested this week.

Anyone have a recommendation for one to get me back up and running? I don’t need the jumbo alternator.

 

[sleepycruiser]

Double post