Temp gauge and sender unit mismatch

Post by **NZJLY** » Tue Jan 30, 2007 7:27 am

Greetings, Olive has just had a new(ish) motor put in, and I have put a new temp sender unit in (I think out of a mini). Only trouble is it sends the gauge straight into the red zone.
Do I need to get a mini gauge to go with it, or can I put a resistor into the circuit, and if so how big.

Thanks in advance

John

Post by **Kevin** » Tue Jan 30, 2007 1:50 pm

John you do realise that is has to be wired through the regulator on the back of the speedo head.

Post by **Scott** » Wed Jan 31, 2007 1:41 am

Kevin wrote:John you do realise that is has to be wired through the regulator on the back of the speedo head.

That's only for the fuel guage, isn't it?

John, you might have to test the guage using a variable resistor to see what measurements are needed for it top operate at cold, normal & hot.
Once you have those, you can get a sender unit to match.

Or go to an auto shop & buy a new guage/sender combination.

Post by **patgarrett** » Wed Jan 31, 2007 2:34 am

Hi it may be the sender not working correctly. Is there a resitance when you swing through it to earth with a multimeter. If not and it is closed circuit it's must likely broken. One other thing might be the reason, is you car changed over to -ve earth. Hope this is of help Pat.

Post by **Packedup** » Wed Jan 31, 2007 6:25 am

Scott wrote:
Kevin wrote:John you do realise that is has to be wired through the regulator on the back of the speedo head.
That's only for the fuel guage, isn't it?

No

In fact, early Minors don't have a stabiliser for the fuel gauge, but still require one when fitting aftermarket temp gauges.

Post by **NZJLY** » Wed Jan 31, 2007 8:17 am

I will try the multimeter tomorrow. I had another after market gauge and sender unit fitted, without routing it via the regulator, but I will try anything

Thanks for the help,
John

Post by **Rob_Jennings** » Wed Jan 31, 2007 9:37 am

Kevin is right,

The temperature sender must be connected to the instrument voltage stabaliser which is a 10V output, connecting to the battery (anything between 10-15v depending on charge cycle) will probably give you full scale all the time.

Polarity of the car is not an issue, the sender is just a thermister (heat dependant resistor) and not sensative to the direction of current flow.

Post by **NZJLY** » Thu Feb 01, 2007 8:41 am

Thanks for that. So I could buy another 10v regulator and run that? It saves me some playing around under the dash time

John

Post by **Rob_Jennings** » Thu Feb 01, 2007 9:49 am

Yes you could.

although accessing the speedo is not too much trouble.