Temp Gauge

[tractor]

I am still struggling with temperature gauge I have earthed the sender I have separate earth on gauge when you turn ignition on the gauge is at zero then start engine it goes straight to eighty degrees then when engine warm stays at 100 pull the wire off the sensor it drops to 80 starting to think gauge is knackered

[magh]

Is it a correct matching sender for the gauge?

[tractor]

Well I really don't know whats going on I rewired tacho into mega jolt and it was reading two thousand rpm but temperature gauge worked perfectly I wire tacho back to edis and tacho works and temperature gauge works don't know what is going on

[tractor]

Scrub that didn't have temperature sender connected

[Guest 2b cruising]

It's that "black art" stuff mate.

Gets me every time I try doing anything with it.

It is the only part of my future engine/dash swap that makes me more than a little apprehensive.

I will probably end up farming that part of the job out. I don't want to loose my car for a long period, and my patience all went out the exhaust some time ago now.

Hope you are all complete for Stoneliegh.

[cb750]

Are you running both the temperature gauge and the Megajolt temperature input from the same temperature sensor? If so then that may be your problem and you would need another sensor for the megajolt.

Rob

[tractor]

tried it both ways rob still the same outcome

[cb750]

You have probably tried this but the only other thing I would try is to wire the gauge straight to a supply and the sender to see what happens. Have cbs sent you the correct sender?

[sj-bradley]

The sender will have a resistance value when cold and another when up to temperature.

 

These two extremes should be what the temperature gauge is expecting. For example (these will not be correct, so you will need to measure these yourself)

 

Cold - sender reading is 1000 ohms

Hot - Sender now says 200 ohms (Could be other way round, but you get the idea)

 

Now you can buy a potentiometer from maplins for the larger value and pretend that is the sender and connect this to the gauge and when you turn the knob, the gauge should vary from cold -> hot etc.

 

(You can also buy a set of resistors, but you need to know the colour code to read these, Black, Brown, Red, Orange, Yellow, Green, Blue, Violet, Grey, White 0,1,2,3,4,5,6,7,8,9)

 

The gauge needs to match the sender ideally, but with some electronic knowledge, they can be made to match

 

The pot above shouldn't cost more than £1 (but, knowing maplin - £2 or so. The cheap LINEAR one is fine - don't get the LOG one if you see it)

 

If you can measure the resistances with the multimeter when hot/cold and the gauge works with the variable resistor, you can see if they match.

 

Simon.

[cb750]

I Used the same principle to check the TPS input for the Megajolt when testing it on the bench

[tractor]

well I have put the old sender back in and disconnected the megajolt from the sender and it is now working also found out why clock runs slow so just fuel gauge to get working the wright way phewwwww

[sj-bradley]

Not so easy. You need to invert the sender output somehow so that the low and high resistances are at the other end of the scale for that particular gauge.

 

I'm working on this, but have not completed it yet.

 

Simon.

[tractor]

got a new fuel sender it just don't fit the hole in the tank and don't think I can make it work by making the best of the two think I will have to make an adaptor plate or cut a new smaller hole in tank

[sj-bradley]

Sounds like the adapter plate is the way to go in that case.

 

Provided of course, that the new sender works the correct way round ... I'd check that out before fitting it.

 

Simon.

[tractor]

will do simon