I just installed a voltmeter and a temperature gauge on y 73 2 liter and have some questions.
1- my voltmeter only gives me 9 volts reading ( the battery is fine ) I plug the Positive to the red wire off the brake pedal switch and grounded on the chassis ) What is wrong ?
2- my temp gauge goes all the way to the top ( red) and fogs after a few minutes of driving. Again what goes wrong ? is it the sensor under the engine oil pan or is it the gauge itself ?

thks

1.
a. Ground connection could have resistance (paint, grease, dirt, etc.). Ideally, should be bare steel and connected to the chassis.
b. Connect a temp. test wire from the VM to the + post on the battery. Should read source voltage (12+ volts). If not, the meter and/or ground connection is faulty. You coild connect the gauge (+ and –) directly to the battery to bypass all the above chassis connections.

2.
Gauge and sensor should be compatible. One or both could be malfunctioning (probably not both). Gauge wire could either be open or shorted to ground. Remove wire from the sensor and observe the gauge. With ignition ON, the display should change.

Something like that.
Sherwood

If your car is a 73 there is a gauge harness under the center floor carpet. Plug your wires in from there. Wiring diagram is available in several places. Do you have temp sending unit installed or did you put one in ? Sending unit and wiring have to be in place for it to work the temp gauge.

Thanks, will re-check all my connections !

Is that the stock voltmeter, or a regular testing voltmeter? If a regular voltmeter says 9V when you put the probes on the battery terminals themselves, the battery is dead. It has at least one or two shorted cells, and won't hold a proper charge any more.

If you're getting the reading on the clamps that go on the posts, there's a small chance that you're seeing a high resistance connection from the posts to the clamps, but a drop down to 9V is a lot of resistance.

If you're using the stock voltmeter in the stock location, 9V may just mean you have some lights on, or you have high resistance connections, or the battery is drained, or dead, or all of the above. If you're using the stock voltmeter across the battery terminals, I'd guess that your battery is dead.

If you have a charger, you might stick the battery on it for ~6-12 hours and see if the voltage comes up to normal levels. (Nominally 14.4V.) If you don't, take the battery to your FLAPS and have them test it.

--DD

Hi Dave , No I am talking about the round voltmeter gauge itself. I conneced it directly to the battery. and will not go over 9 volt . Battery is good .