Temp gauge not working AW11

[Cai]

Hey guys, I figure someone might know how to better diagnose this issue than I can. The temperature gauge in my AW isn't functioning. When I first bought the car it was slightly working, showing very low readings even when at running temp, but over the short time I've owned it the gauge has stopped showing any readings. It simply sits at dead cold!

I know the thermostat is working, as the radiator hoses stay cold for a while before heating up as expected. However, I don't know how to easily test whether it's the temperature sensor, wiring, or gauge that are faulty. Any advice would be appreciated!

[mknz]

Put a multimeter on the temperature sender and on the battery, it's in the BGB, it should change readings from 0 to 6V as the temperature changes.

If it does that then check the wiring behind the gauge but you need to remove the dash carefully because it's really easy to crack.

You can confirm it's the gauge by putting 12v across it and it should read max

[Cai]

Thanks mknz.

Running a wire between the sender wire and ground didn't affect the gauge. Although, the manual says to have a 3.4W bulb between the sender wire and ground, so I'll have to try it with that just in case it only works at a specific voltage/amperage or something like that.

I did take off the dashboard to have a look at the resistance of the gauge. Between the "TU" (temp unit?) - "IG" (ignition?) terminals it showed the correct resistance, but between "IG" - "E" (earth) and "TU" - "E" the resistance was lower than it should be. The manual says they should be 145.8 and 201.8 Ohms respectively, whereas my multi-meter read 8-something and 14-something respectively. Possibly a buggered gauge, but those readings seem too close to correct for it to be too buggered.

[Redmist]

Have known the sender unit and wire to suffer from corrosion.
With the ignition on, earth the sender wire briefly. The gauge should do a full deflection.

John