View Full Version : TR4/4A Temperature and Fuel Gauge Wiring...Help Wanted Please

12-21-2015, 07:51 PM
Currently wiring to the above gauges, but not sure where the power wire from the voltage stabilizer goes to on each.
Gauges are in situ, so I cannot see if there are any markings on the back of the gauges.
Fuel gauge...power to empty side terminal. ??????
Temperature...power to high temp side terminal ????????

12-21-2015, 08:46 PM
Each gauge has two terminals on the back. One goes to the output of the voltage stabilizer, the other goes to the sender. Doesn't matter which one is which.

12-22-2015, 12:44 AM
Thanks TR3driver....Pardon me for saying this....are you absolutely sure.

12-22-2015, 01:17 AM
Yup. The active element inside this type of gauge is just a length of resistance wire, wound around a bimetallic strip. It doesn't care which way the current flows through the wire, which is why the same gauge (and connections) will work on either positive or negative ground. There are some nice photos of the workings at https://www.mgb-stuff.org.uk/fuel.htm

Ok, one caveat : I'm assuming you are talking about stock TR4 or TR4A gauges. Aftermarket gauges, even those made by Smiths, may be different.

Geo Hahn
12-22-2015, 03:24 PM
Thanks TR3driver....Pardon me for saying this....are you absolutely sure.

Well, I know I smiled when I read that.

You've only been on the Forum for a year so you may not have noted a pattern. Randall doesn't know everything, but when he does offer an answer you can 'take it to the bank'.

12-22-2015, 05:44 PM

12-22-2015, 07:53 PM
Thanks for the vote of confidence Geo, but it's not strictly true. I do make mistakes just like everyone else; along with the occasional brain fart and senior moment.