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Temp gauge and sender unit mismatch
Posted: Tue Jan 30, 2007 7:27 am
by NZJLY
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
Posted: Tue Jan 30, 2007 1:50 pm
by Kevin
John you do realise that is has to be wired through the regulator on the back of the speedo head.
Posted: Wed Jan 31, 2007 1:41 am
by Scott
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.
Posted: Wed Jan 31, 2007 2:34 am
by patgarrett
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.
Posted: Wed Jan 31, 2007 6:25 am
by Packedup
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.
Posted: Wed Jan 31, 2007 8:17 am
by NZJLY
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
Posted: Wed Jan 31, 2007 9:37 am
by Rob_Jennings
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.
Posted: Thu Feb 01, 2007 8:41 am
by NZJLY
Thanks for that. So I could buy another 10v regulator and run that? It saves me some playing around under the dash time
John
Posted: Thu Feb 01, 2007 9:49 am
by Rob_Jennings
Yes you could.
although accessing the speedo is not too much trouble.