It might be broken depending on the tester, either that or you have straight coolant or water.
You just look where the needle is pointing. The trick is to figure out which scale to look at and how much to multiply it by ... but the selector switch is your clue.
A basic antifreeze tester
You can go to any parts house and for about $5.00 you can buy a tester. It is simple to operate.
By Taste. Just kidding use an auto antifreeze tester
Working a blood sugar tester is very easy. All you have to do, is prick your finger with the needle, and put the blood droplet on the stick to get your result.
If it is a ball type tester, use the bulb to suck in some coolant, then count the number of floating balls. The chart will tell you the coolant rating. If it is the needle type, then suck up coolant and the needle points to the coolant rating.
analog is a D'arsonal movement (an indicator needle over a scaled background) and a digital meter is a LCD display that has no movement
They float at different densities. If the density of the water/antifreeze mix is too weak, the number of balls floating will indicate that, if the mix is correct, they'll indicate that.
Need to get a pressure tester for rad. Do not pump up over 10LBS. And then look at the rear corners of the intake real close for leaks. The vortec engines are none for intakes leaking antifreeze. BE SURE TO CHECK ENGINE OIL CLOSELY FOR ANTIFREEZE
You will need a small electrical multi-tester to test the switch. Set the tester to "ohms". Disconnect the wiring from the switch. Touch one of the tester leads to one side of the switch and the other lead to the other side. Your reading should be zero. Have a friend depress the brake pedal, and the needle on the meter should swing left to right. If the needle does not swing then the switch is bad. If it swings then the problem is elsewhere in the wiring. The multi-tester can be found at hardware stores, auto parts stores and department stores.
simply means the tester's measurement is displayed in an analog way (not digital) For example: a moving needle that points to a scale a clock with hands is ANALOG a clock that displays the time like this (11:55pm) is DIGITAL
It may have a leaking head gasket. Has the coolant level dropped and needed more antifreeze . If so check it with a pressure tester