Battery not charging

[D@vid]

Hi guys,

I really need your help again. I have been working for years on the restoration of my 1973 Porsche 911T. Almost everything has been done; the car was taken apart down to the very last bolt and nut, and now I’ve finally reached the point where the car is back together again. However, I’ve run into a problem that I can’t seem to solve myself, even after going through the entire forum about this specific issue.

What’s going on? As mentioned, I’ve rebuilt the car from the ground up, including a partially new wiring loom. Now that everything is finally coming together and the engine is back in the car, I’ve discovered that the (new) battery is not charging. When I turn on the ignition, the red alternator warning light on the gauge lights up, but it does not go out when the engine is running. At the battery I measure just over 12 volts.

Initially, I thought it might be due to the voltage regulator. I replaced it just to be sure, but without success. The alternator has not been rebuilt (I know, I should have done that), but it functioned well before the restoration.

I’m unfortunately not very experienced with electrical issues, but could it be that the connectors on the oil temperature and pressure gauge were not reinstalled correctly?
I believe I connected the wiring the way it was originally, but to be honest, I can’t really judge whether I may have made a mistake.
I would greatly appreciate it if you could take a look with me.

So:

1. The alternator is not charging the battery when I measure at the battery.
2. The alternator functioned properly before the restoration, but there’s no absolute certainty that it’s actually charging now.
3. I replaced the original Marchal voltage regulator with a solid-state alternative without success, and the old one has since been reinstalled.
4. With the ignition switched on, the charge warning light in the temp/oil pressure gauge illuminates. When the engine is running, the light does not go out.

[Richard Knight]

Have you changed the charging light for a LED?

[D@vid]

No I used the original lightbulbs

[30westrob]

I suggest your next step is to remove alternator to check all wireing continuity and brushes. If no smoking gun, take or send the alternator and VR’s to a specialty automotive electrical shop. They are equipped to properly diagnose. Rob

[ian c2]

I cannot help , but your picture doesn’t seem to match your diagram using my “spot the difference” skills . ( I can also find Waldo and do sudoku to a reasonable level )
Wire missing on 1 plug , and wrong colour jumper on 2-5

[D@vid]

Thanks guys, I hoped I didn't have to remove the alternator to check if it's working but I'll probably have to bite the bullit.
allso, thanks for spotting the missing wire. will check what went wrong.
Just found a new problem... frunk won't open when I pull the handle.... great...