Not charging, no charge light, dim headlights, etc

[ScoopMan]

I have a 1979 Spider. Not really sure where to start. The car starts and runs with a charged up battery, but the charging system is awol. The charge light never turns on, and the bulb is good. Headlights are super dim, wipers barely move, heater fan does not run. I thought at first it was the alternator, but the fact that the charge light never turns on makes me think there is a loose wire somewhere. Any suggestions are welcome. Thanks!

[So Cal Mark]

the light needs to work or the alt won't get energized. How do you know the light works if it never turns on?

[ScoopMan]

Sorry Mark, I was not clear. I removed the bulb and tested it. FWIW the oil pressure bulb lights with the ignition on, as well as the hazard light button. I checked voltage at the fusebox, and fuses 1, 2, 9 and 10 were around 10 or 11 V. Fuses 3-6 (headlights) were only around 1 or 2 volts. Fuses 7 and 8 were 5.3 and 6.9 V, respectively. No voltage at all in 11 and 12, but I think these are for power windows, which mine does not have (I get this from reading whatever wiring diagrams I can find).

[majicwrench]

Help me out, does a 79 have a regulator?? If it's like a 72, one of the wires should be 12v key on. Do you have power at the big wire at back of alternator?? When checking fuses, very gently check both ends, touch volt meter or test lite to the terminal in the fusebox not the fuse, obviously should have power on both sides.
Keith

[azruss]

what is the volts across the battery when the motor is running. if it isnt above 13.5v, then your alternator is not charging. this could be a bad alternator or a bad regulator. later cars had modern alternators with an internal regulator. earlier cars had an external. usually a big rectangular box on the driver side inner fender.

[ScoopMan]

Yes I checked voltage at the battery with the engine running at 2500 rpm, and voltage was around 10V or so, so I know it is not charging. But like I said, the charge light NEVER lights, which is why I think I might have a bad connection somewhere. Wires at the alternator appeared to be connected OK, but access is not too easy without removing lots of stuff. I pulled off the air cleaner, but did not feel like pulling fuel lines and stuff so I could have an easier time getting to the wires. I am doing the shade tree thing, and it was getting near dinnertime when I went under the hood to look. I had to bag it until I have more free daylight time.

I was able to see the back of the alternator, and I believe the regulator is mounted to it.

Looking elsewhere here I have seen nearly as much written about the 'brown wire fix' as I have about Kim Kardashian. Lots about grounding pods too. Could these be possible culprits?

[ScoopMan]

Looking at the diagram, I must now guess that it is probably either the alternator/regulator or the wire to the charge light, since I am hot at fuse 10, which is powered off the alt terminal on the battery side. Since the alt is not producing at all, the likely hood seems to me to be the alt and or VR, not the wire to the charge light.

Any point to testing the VR, or just better to replace the combined unit?

[So Cal Mark]

you gotta have power in the wire from the light or the alt won't charge

[spider2081]

Mark is right you need to measure the voltage on the small wire on the back of the alternator. Measure this voltage with the wire disconnected from the alternator engine not running and the ignition switch in the run position. You should have very close to the same voltage on that wire (alternator field) and the alternator output wire. If there is no voltage read my reply under topic Engine and tuning subject for post "alt. light dosent turn on"
The voltage on the field wire will be much less when connected to the alternator as the field circuit provides the ground for the alternator light when the alternator is not spinning, engine not running.

[ScoopMan]

OK, thanks guys! I will try what you recommend, and let you know what I find.