13 replies to this topic

[DClarke1954]

I have searched the forum but not found the same fault/symptom.

 

The Temp gauge never lifts of the "Stone Cold" position, no matter what.

Ground the wire and it shoots to "H" quite happily.

Tested the sender in boiling water and it goes from 650 Ohms when cold to 92 Ohms when in boiling water.

 

So, if the gauge appears to respond to a resistance to earth change and the sender changes resistance with temperature why no joy in real working?

 

I can only assume (ASS-U-ME) that the senders I have are not matched to the resistance values the gauge works with/is looking for.

 

Are there alternative sender types and resistances?

 

Thanks in advance.

 

Dan.

[stuart bowes]

have you checked continuity on the wiring ?

[KTS]

from the following, the sender resistance you're measuring would appear to be in the right ballpark

 

https://www.theminif...ge-calibration/

 

from your description of the issue it's possible the sender does not have a very good connection to earth - is there a good earth strap from the engine to the body, and/or has someone used ptfe tape on the sender thread to prevent leaks ?

[Steam]

It is totally hit and miss whether a sender is "matched" to a gauge. You can have brand new units and they will still all be different. The only workable solution I have found is to mix and match senders and gauges until you find a combination that does what you want.
I assume you have checked the gauge has the correct supply voltage ang good earths.
Alternatively you can use a potentiometer or multiple reistors to work out what you need the find a sender that matches those findings.

[Chris1275gt]

PTFE tape on the thread of the sensor would not affect the thread contacting the metal of the block.

[DClarke1954]

I will check the resistance of block to earth on the chassis, but everything else measures fine when using the block as the "ground" so I don't think it is that.

If grounding the single wire of the sensor causes the gauge to work and show "Hot" plus off the scale, then the continuity of the sensor wire must be good, it can only be the resistance range is wrong I think.

I have tried 2 of the same part number (thinking maybe the first one was faulty), now I will try the alternate part number.

[Cooperman]

Best option is to fit the capillary type gauge kit as supplied by Mini Spares. The gauge reads in degrees and is accurate.

[timmy850]

Is the gauge wired using the voltage regulator or with a full 12V?

[Spider]

It is totally hit and miss whether a sender is "matched" to a gauge. You can have brand new units and they will still all be different. The only workable solution I have found is to mix and match senders and gauges until you find a combination that does what you want.
I assume you have checked the gauge has the correct supply voltage ang good earths.
Alternatively you can use a potentiometer or multiple reistors to work out what you need the find a sender that matches those findings.

 

Agree with this from Dave.

What brand of gauge are you using here ?

[andyapanel]

What happens when you attach the sender to its wire and put it in hot water?

[mbolt998]

Yes next stage is to do what andyapanel suggested. FWIW mine reads somewhere around N at 92 Ohms (I tested it with a variable resistor) so I think that's normal. What if there's much less than 10V going to the sender? I guess that might happen if your voltage regulator is hosed. The instruments have their own voltage regulator (a little rectangular thing attached near the back of the dials, at least that's where it is on my car). Maybe if you had a much lower voltage there the ground test would still work but not the gauge?

[DAC1952]

I have this same issue.
When I earth the wiring loom the gauge shoots up to high but when just ticking over it’s permanently cold, even when in hot water. New wiring loom installed and other clocks seem to be working ok, although fuel gauge is not buaye as it could be.

[Spider]

I have this same issue.
When I earth the wiring loom the gauge shoots up to high but when just ticking over it’s permanently cold, even when in hot water. New wiring loom installed and other clocks seem to be working ok, although fuel gauge is not buaye as it could be.

 

Does your car have an Alternator or Dynamo ?

[DAC1952]

Hi Spider, mine has an alternator. It’s a new one at that too.
All very odd in my mind.