Alternator issue- maybe..., Voltage gauge and Charging light issues Options

[creeves84]

So I'm lost on this one- here is what I have. its a 1975 914 2.0, my issue is the following:

Car was running fine- went to put it in the garage and notice that the fuel gauge was on reserve (but had about 10 gallons in the tank), gave it a bit of throttle to move the car and the charging light came on. I looked at the volt gauge and it was not registering at all.

Thought it may have been a voltage regulator, as at times when applying the brakes- the gauge dropped from 14 to about 12 volts, off the brake back to 14 volts. Car was acting weird earlier, I think it was running off the battery only- tach was acting weird, seemed like limited power.

I replaced the voltage regulator- the gauge still doesn't read, charged the battery (new AGM). It was low at 11 volts with no load (not completely charged yet), started the car, tested the battery again with a hand held meter - no increase in voltage at the battery.

I'm thinking its the alternator but the question I have, is the volt gauge pulling the reading from the alternator and that is why its not reading? is the fuel gauge not working due to low power from the battery working off reserve? Am I going down the right path thinking its the alternator?

[TheCabinetmaker]

Did you check fan belt tension?

[Spoke]

Check all the fuses, make sure they are ok and the belt is tight.

With the engine running, measure all 3 wires on the relay board at the connector from the alternator WRT to chassis ground. There is a ground or chassis stud behind the relay board. Record the voltage and let us know what you measured. These 3 voltages will speak volumes about the health of the alternator/Voltage regulator.

[GregAmy]

Make sure you didn't accidentally dislodge (or pop) fuse S9. That's the one that powers all the gauges and is on the car side of the voltmeter light.

[dr914@autoatlanta.com]

loose fuse??

So I'm lost on this one- here is what I have. its a 1975 914 2.0, my issue is the following:

Car was running fine- went to put it in the garage and notice that the fuel gauge was on reserve (but had about 10 gallons in the tank), gave it a bit of throttle to move the car and the charging light came on. I looked at the volt gauge and it was not registering at all.

Thought it may have been a voltage regulator, as at times when applying the brakes- the gauge dropped from 14 to about 12 volts, off the brake back to 14 volts. Car was acting weird earlier, I think it was running off the battery only- tach was acting weird, seemed like limited power.

I replaced the voltage regulator- the gauge still doesn't read, charged the battery (new AGM). It was low at 11 volts with no load (not completely charged yet), started the car, tested the battery again with a hand held meter - no increase in voltage at the battery.

I'm thinking its the alternator but the question I have, is the volt gauge pulling the reading from the alternator and that is why its not reading? is the fuel gauge not working due to low power from the battery working off reserve? Am I going down the right path thinking its the alternator?

[creeves84]

Thanks guys- I will double check the fuses- I did earlier but I have to admit I could have missed something.

I think it maybe more then a fuse, as the temp gauge and seemed to work, but it would be nice if it was just a fuse.

The fan belt appears to have decent tension but a good reminder to look at everything.

[creeves84]

Check all the fuses, make sure they are ok and the belt is tight.

With the engine running, measure all 3 wires on the relay board at the connector from the alternator WRT to chassis ground. There is a ground or chassis stud behind the relay board. Record the voltage and let us know what you measured. These 3 voltages will speak volumes about the health of the alternator/Voltage regulator.

Thanks for the details, will check it out and post the results.

[ndfrigi]

I remember it happened to me before and the ground is the culprit.
Check battery ground, tranny ground and all the body grounds of the electrical. But that is my experienced on my previous car.

[VaccaRabite]

I've been there done this. There are checks to can to to verify the alternator is working.

LOTS of information in my thread here: http://www.914world.com/bbs2/index.php?showtopic=332381

After replacing almost everything my issue ended up being grounds and I likely did not have to replace ANYTHING. Start at post 59 and read what Spoke had to say about testing grounds. There is also a test in there (unplug the VR, short D+ to DF) and test voltage should jump to about 17 volts as it puts the alternator into max effort mode - don't do this for long - just long enough to test the alternator. At idle this test will put a noticeable load on the motor, and if you run it for too long it will damage your battery. Also if you are getting only 13.5 14 volts (and the motor get a load on it when you do the test) that also a clue that you have ground issues. If you run the test and have lower then 12.5 volts and no load on the motor, your alternator is likely dead.

Zach