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Possible faulty coolant sensor
andy996tt - 6/5/12 at 02:36 PM

Please bare with me. I'm a noob in the world of kit car electrics.

I've got a track only Tiger Avon. I bought it already built.

I've noticed the coolant gauge doesn't move. I've warmed up the car for around 5 minutes and there's no movement.

I checked the voltage to the gauge which was just over 5 volts. Is this right ?

I then dabbled with a multimeter to check resistance. This is where I'm struggling. I had the multimeter on 200k and on the sensor on top of the stat housing I got around 55. I then checked the sensor underneath which I think is for the gauge. This came back as 00.1.

My tiger has a blacktop with a weber alpha ecu.

Also if that sensor does the gauge. Then how does the Ecu get a temp reading ?

See pic below for the sensor in question

andy996tt - 6/5/12 at 02:38 PM

mark chandler - 6/5/12 at 03:09 PM

You should have two sensors, one for the gauge and one for the EFI (very important).

The picture of the sensor you have posted below looks like a gauge sensor, although I do not know the values for the one you have typically when using a multimeter set to ohms expect to see 4000 ohms when cold, 20 - 30 ohms when hot.

The sensor works to earth, depending upon your gauge it may have a battery via a voltage regulator which will provide less than 10v, others run straight off the battery.

So wiring then is battery - guage - sensor - earth or battery - voltage regulator - guage - sensor - earth.

nb/ the voltage regulator will tend to be a part of the dashboard wiring in cars, if you have an early smiths type guage you will need one, if a more modern gauge probably not.

Regards Mark

andy996tt - 6/5/12 at 03:32 PM

The one on top has nothing connected to it ?

The car runs well but I can't work out where the ecu is getting its signal from ?

RK - 6/5/12 at 03:39 PM

Is the broken wire to blame, by any chance? Try hooking that up to the sensor above and see what happens.

The gauge sensor always has ONE wire coming off, and the unit is earthed to the cylinder head. The ECU coolant sensor will have TWO.

andy996tt - 6/5/12 at 03:55 PM

The pictured sensor is the gauge sensor then. But I have no broken wires.

avagolen - 6/5/12 at 04:36 PM

Hi,

By the look of the sensor in the photo, there is a wire 'crushed' under
the sensor - suspecting a 'plastice thermostat housing' and this is the earth wire.
Check the wire is actually connected to the sensor body :- 0 -1 ohm.
Then check the sensor body to chassis ground.

This will tell you if you actaully have a ground path for the instrument signal.

HTH

Len.

andy996tt - 6/5/12 at 04:45 PM

Checked that. The earth is good.

Anyone know the part number for the sensor. If its cheap it worth a punt.

I'm assuming when I take the sensor out the waters going to come out

avagolen - 6/5/12 at 04:59 PM

Thats ok then.

Sensor will allow the fluid to run out, but not a lot - if you are quick......

The sensor may be specific for the gauge - Search for the make on the net and go from there.

Basic sensors may work, but that may be why it is not working

Len.

rusty nuts - 7/5/12 at 04:01 PM

Is the engine reaching normal operating temperature? if it isn't the thermostat may be faulty and no amount of testing the gauge/sensor will do any good.

andy996tt - 7/5/12 at 04:04 PM

Surely the gauge should rise a little before the stat opens ?

rusty nuts - 7/5/12 at 04:21 PM

quote:
Originally posted by andy996tt
Surely the gauge should rise a little before the stat opens ?



Only if it has a stat fitted