This latest version of our gauge matcher can match virtually any resistive sender to any gauge designed to read resistive senders. Your sender signal can be calibrated to your gauge at five points on the scale which can compensate for unusual sender characteristics and mis-shaped fuel tanks. The matcher also has a dual-stage output for a warning light - steady first, then flashing (for example, fuel level or over-temperature). There is also an auxiliary, programmable output that can operate a relay to switch on a cooling fan at a specific temperature. Included with each matcher is a miniature, 22-turn variable, 0 to 500 ohms, resistor. This can be used as a 'dummy' sender to transfer your original sender's resistance readings to the matcher on the bench. All this in the size of a matchbox - 38 x 80 x 22mm. Full instructions included. Basic electrical knowledge and a multimeter would be helpful. Weight 30 gms. MULTI GAUGE MATCHER #GMATCH Note: Will not work on Positive Earth vehicles. HOW TO DO IT Gauges and senders should always be installed as a matching pair. That is - the resistance of the sender, through it's operating range, whether it's measuring water temperature, oil pressure or fuel level in the tank, is perfectly matched to the instrument (gauge). The indicator needle, (or digital read-out) on the gauge moves when the resistance of the sender changes - with a rise in coolant temperature or a change in fuel level in the tank. Try an experiment. Set your multimeter to it's lowest 'Ohms' range and connect the two probes to, say, a water temperature sender. One wire to the terminal and the other to the sender body (or to both terminals if it's a two-terminal sender). Now warm the sender with a heat gun or suspend it in hot water. You should see the meter reading change as the temperature of the sender rises. But what if you don't like the look of the standard gauge and you want to change it for a more modern or high-tech one? It's pretty unlikely that your original sender will match the new gauge and you may well have a gauge reading of 80ºC when the actual temperature is 105ºC - disastrous ! Sender resistance changes are usually linear so it's all quite simple so far, but things get a little more difficult with an irregularly-shaped fuel tank. The rise and fall of the fuel sender float and it's resistance readings may have little relation to the amount of fuel in the tank. We've all experienced it at some time. The fuel gauge hardly moves for hundreds of miles then suddenly drops to 'EMPTY' over just a few miles - Panic ! This is a job for Gauge Matcher. You can program five sender resistance readings into your gauge at any points between empty and full so you get a smooth, regular, accurate change on your gauge. Here's how. Fill and measure the tank capacity. Let's say it's 12 gallons. Empty it again and take an 'EMPTY' sender reading. Put in 3 gallons and take another reading. Then another 3 and another 3 then a reading at 'FULL'. So, you'll have a list of 5 sender resistance readings at EMPTY, 3 gallons, 6 gallons, 9 gallons and FULL. Now, if it's convenient, you could do all that in the vehicle with all the components installed. Or, you may find it easier to do it on the bench using the little blue variable resistor that's included with the gauge. Duplicate your recorded resistances on the variable resistor, one at a time, measuring them with your multimeter and program them into the matcher.
