Why is my volatage so high?

[UR2H]

I read up on Blue's Atlantic Z site about the external voltage regulator to an internal regulated alnernator conversion. I think I will do this regardless if my voltage regulator is bad or not. Such an easy upgrade. I like the distributor upgrade too, seems a bit tougher...for me anyways. Still seems managable though.

Kind of a noob question here but do 77 280Z's have a in dash voltage regulator?

Oh and BTW GREAT site Blue.

[Zed Head]

Download the FSM and look in the Engine Electrical section - Charging Circuit. It will tell you all about your external regulator, where it's located and how to test it. It's a small metal box in the engine bay.

[UR2H]

I replaced the external regulator with an old one that I never tossed away and now the voltage seems okay. Stays right around 15 at idle, closer to 14 with the lights on and closer to 16 with throttle.

Kinda funny I never threw that old one away. I only replaced it with a new one cause my mechanic advised that I change it as it may have been the reason my alternator initially failed. Also funny that the older one is okay and the newer one that is maybe 3 years old failed already. I definitely upgrading to an internally regulated alternator.

[UR2H]

Download the FSM and look in the Engine Electrical section - Charging Circuit. It will tell you all about your external regulator, where it's located and how to test it. It's a small metal box in the engine bay.

I downloaded the FSM. Thanks.

[5thhorsemann]

You have a volt meter, if connected properly it should be reading the entire potential across the battery terminals, to include the charging circut. The battery should be around 12V, we know this to be true. the only other thing capable of creating electrical potential (voltage) in the car is the alternator, which is governed by the regulator. Therefor, since you are seeing a full field condition at the battery, via your new gauge, (and this has been verified with a meter) your problem is reg. wiring, or the reg. itself.

Please excuse the scientific speak, just read the vaporlock thread front to back and it put me back in college mode. I need a beer.

[UR2H]

What is the correct voltage my gauge should be reading?

[beermanpete]

What is the correct voltage my gauge should be reading?

14 to 15 volts is normal with the engine above about 1500 RPM. At idle the voltage will fall a volt or two depending on what loads are turned on, lights, heater, etc.

[UR2H]

These are my readings-

when warmed up at 800RPM

~14.8-15V at idle

~12.2-12.5V at idle with headlamps on

when driving

~15.5-15.7V regardless if headlamps are on or off

Are these with range?

[SteveJ]

Did you take the first set of readings with the voltmeter or your gauge (I trust a voltmeter reading more.)? Also, have you checked the accuracy of your tachometer? Those factors can influence your results.

If you look at the EE section of the FSM from EE-11 to EE-23, there is a very good description of testing the electrical system and what the results should be. It even has a troubleshooting guide.

If your measuring techniques are good, I would say you're a little high on the voltage. However, if you notice in the FSM, there are temperature variances for the acceptable range. The procedures the FSM has for adjusting the regulator are for a stock regulator. They won't work on a solid state regulator.