[Phill]

Hi guys,

my dad had a bit of a 'barn find' last weekend. He bought a highly spec'd Uk 1994 1.8 Mk1 with only 36k on the clock. The owner had a bit of an accident in it about 10 years ago and parked it up in his garage and never went back to it.

Anyway we collected it last weekend and my dad went about getting it up and running. When we get it back to his we tried a fresh battery in it, it would turn over but wouldn't start - turns out it had an immobiliser fitted and the guy we bought it off had gone and lost the fob to disarm it. We traced it all back an un-wired it so now it's up and running.

The only problem we now have is the temperature gauge isn't working. It gets upto temp and the fan comes in and out like it should be no gauge.

I down loaded a manual via here and it seem's it's only for the early 1.6 model as that show's the temp sender mounted in the thermostat housing on the front of the engine. This engine has a totally different housing on it and there is no evidence of a sender ever being there.

We've found the sender that is on the back on the engine under the coilpacks & CAS unit. That has a green plug and 2 wires going to it but I think that ones is for the ECU. Is it possible that the later mk1 1.8 just has the one sender? Could we have disturbed the wiring when we were stripping the immobiliser out going from the ECU to the gauge??

Any help would be greatly appriciated as i'm reluctant to start putting the car back together until we've got this issue sorted.

 

[Mr Slow]

You're correct the 2 wire sensor is for the ECU, however if you look closely in that area you'll see a single wire going to a sensor just below the 2 wire one.

It's this single wire sensor, (eath is through it's body), which drives the dashboard clock.

 

[Phill]

O.k cheers for the quick reply - i'll take a closer look. Space is tight back there so maybe i'm not looking hard enough!! lol.

 

[Mr Slow]

it's a pig to get at... I swopped mine with the engine out

 

[alfajerry]

Almost certain there are two, keep looking.

 

[Mx5 Dan]

Easier to see if coil packs are removed first

 

[Mr Slow]

Easier to see if coil packs are removed first

Dan it's a 1.8 the coilpacks are on the otherside/not in the way

 

[alfajerry]

Have a look here

http://www.mx5parts.co.uk/advanced_search_result.php?keywords=temperature&x=0&y=0

to see the different senders you could find

 

[niggle]

I down loaded a manual via here and it seem's it's only for the early 1.6 model as that show's the temp sender mounted in the thermostat housing on the front of the engine. This engine has a totally different housing on it and there is no evidence of a sender ever being there.

That is actually a thermo switch for the radiator cooling fan on 1.6 models. On the 1.8 the cooling fan is switched on by the ECU based on the Engine Coolant Temperature sensor screwed into the back of the cylinder head.

 

[Phill]

This is the pic of the sensor that is on my dad's car :

Sounds like we've caught a wire when removing the immobiliser - anyone got a wiring diagram for the later UK 1.8? Or could someone give me the pin-out on the ECU for the wire that goes to the gauge?? The wire at the gauge is black with a blue trace but there are several of these at the ECU end!!