Okay, well I got my car running finally if you did not know. It was a bad CAS sensor, but now the water temp gauge on the dash goes straight to H as soon as I turn the car on. My fans still kick on, and my AEM is showing correct temp 176 full warm. What the hell could this be?

 

stock gauge or aftermarket, change the sending unit

 

Stock gauge on the dash, well if the sending unit was bad wouldn't my AEM not be reading temps?

 

No there are 2 sensors, one is a single wire sender in the back of the head which feeds the dash.

There is another 2 wire sensor in the back of the head which feeds the ECU.

 

On the 1.6L isn't the single wire sensor in the front thermostat housing?

I've long since moved mine around with reroutes and forget, but that should be the one that feeds the gauge.

You can definitely search though, there have been threads on it.

Richy is correct in that the two wire that original resided in the back of the head feeds your ECU.

The 1wire sensors are cheap and easy to replace, and the wiring...err...kinda simple.

 

If you are running an MS, you don't use that one wire sensor, which I believe is what switches on the fan at a certain temperature. You can vary the temperature at which the fans kick on, therefore it requires a variable sensor, so it uses the rear sensor.

Edit: uh...same for AEM I think.

 

That sensor on the thermostat cover is a thermostatic switch to activate your fans.

AFAIK the 1.6 still has a tiny 1 wire sensor in the back of the head for the dash signal.

EDIT: Just checked the wiring diagrams, I'm right, the 1.6 has in effect 3 water temp sensors, the one that feeds your dash has a black/blue wire colour, likely after all this time it'll mostly look black, but look for something like that around the back of the head and you'll find your sensor

(Fig3 for the thermoswitch and Fig4 for the dash signal)
http://neomiata.com/garage/Wiring%20...20Diagrams.pdf

 

That's right...remember now, three sensors.

I ended up with the fan thermoswitch on the back of the motor and just squashed it to not contact firewall. MS handles fans. My 2 wire ECu sensor is now up front, easy to check and service.

 

Why do you have the thermoswitch if your MS controls the fans? It's either one or the other controlling them?

 

Figured it out, I broke off the little metal piece that goes the plug slides into. I googled but found nothing, does anyone know the name or product number for this part. It looks like I will have to replace it.

 

Those gage senders are ~ generic…I got one for about 5 bux for a Miata locally at an AutoZone.

 

Sounds good thanks!

 

Looks like this:



http://www.mx5parts.co.uk/product_in...roducts_id/847

 

It's not functioning...it's disconnected, and flattened for clearance. It's simply filling a hole.

 

What color wires are running to this sensor? Black/Blue or Yellow/Red?