Temp gauge and senders

[ghia70]

After some advice, temp gauge is not working, 1968 car with temp gauge part number - 901 741 501 04. Purchased new sender unit however when connected needle on the gauge flicks and stays to the far right. Was there another style type of sender ? Do you need to match sender to gauge ?

Wiring is negative, positive and sender unit feed to the G terminal. Bypassed wiring loom just to make sure it was not a cable problem.

Sender works as measured the resistance when in hot water, increase and decreases with temp change.

Any advice appreciated.

[Strictly]

Bypassed wiring loom just to make sure it was not a cable problem.

Do you mean you earthed the cable, to confirm the cable to guage (and guage) was working correctly? If not earth the cable, and the cable should move to full with ignition on, and to off with the ignition off. or the other way around, im not sure for a 912 - see below

I had a similar problem yesterday with a 911, on the oil pressure, after changing the sender. I replaced the sender and it remained stuck at full (top in my case). I then earthed the cable to a really good bright earth like a new bolt fitted, and the guage went to the opposite (bottom in my case).

I then reconnected it to the sender and it worked as expected (i.e showing oil pressure with rpm). Im sure it was an abnornmatly, but in my case I needed to jolt the guage into working correctly again. It probally indicates that I need to investiage my guage earth, or main engine earth or etc.

Luke