PDA

View Full Version : Testing factory gauges



Geerbangr
10-18-2014, 09:56 AM
Do you guys have any specific method for testing factory gauges. I'm working on a 59 Silver Hawk.

I'd like to bench test them before an install.

paul shuffleburg
10-18-2014, 10:07 AM
Simply run a wire from each post on the back of the gauge to the pos. & neg. on the battery and the needle should climb to the
right. Don't let it stay pegged or you will burn up the gauge.

Geerbangr
10-18-2014, 10:13 AM
Thanks Paul, I don't have the dash apart yet. Are all the gauges electric ?

paul shuffleburg
10-18-2014, 10:49 AM
The oil gauge is mechanical as is the speedometer of course.

StudeRich
10-18-2014, 02:25 PM
I know electrics pretty well, but not a Electronics trained pro, so do I misunderstand something here, you electronics Majors can help me understand this. Gord?

That is NOT how the Stude. Shop Manual says to do it.

Are you very SURE about that Paul? The Temp. and Fuel Gauges only get Positive 12 Volts on the (+) terminal and a Sender regulated amount of OHMs ground on the Negative Wire/Terminal. A full 30 AMPs, 12 Volts could fry them? :confused:

rstrasser
10-18-2014, 03:27 PM
As said previously the oil pressure gauge is mechanical. You could use 20 pounds of air pressure to see if the needle moves.
You can not test the ammeter by connecting it to the positive and negative terminals. It will instantly burn out. Connect the + terminal to the battery and the negative terminal on the meter to one of the leads of a test light and the other lead to the battery negative terminal to a light bulb socket. You should see a little deflection of the meters needle. The higher wattage of the test light the more the needle will deflect.
Now for the fuel and temperature gauge. It is best to have some sort of resistor between the negative terminal of the meter and the battery ground terminal to limit current flow to the meter.
If you have the original style tach I am not sure how to test it as it uses a generator (alternator) inside the distributor to power the tach. I don't know if it uses AC or DC voltage. I am not even sure if they offered a tach in 59.
Ron

JoeHall
10-18-2014, 03:45 PM
About 99 percent of the amp gauges are OK, so I do not bother checking them. Ditto for oil gauges, except they sometimes stick a little, but a tap or two with the fingertips (on the crystal) will usually take care of it. If it continues to stick, you can decide if its bad enough to change, or if you can live with it.

As for the gas and temp gauges NEVER ground them till they peg; that insures at least a 50 percent probability of frying. Run a hot wire to the positive terminal, then a ground wire to just touch the sender wire terminal. Watch the needle closely, and the needle should start to move in a second or two. VERY IMPORTANT, as soon as the moves off the (lower) peg, even a fraction, IMMEDIATELY disconnect the ground. If it moves off the peg, it is good. If it does not move it is bad. If it moves off the peg and immediately flips to the high peg it is bad.

Geerbangr
10-18-2014, 05:11 PM
This is great knowledge you guys have given me. Thank you very much. Once I get the gauges out and test them I'll report back with my findings. Thanks again guys.