I'm not talking about the temperature sending unit by the oil filter, I think theres another water temperature sensor closer to the front and top of the engine and what is it for ? What sypmtoms might come up if it is not functioning well? As usual, Thanks! for any help...

 

The sensor is used for the electric fan that sits in front of the AC condensor... it should turn on at aprox 90 degrees C ... with the ignition turned on, if you unplug the single wire from the sensor, the fan should turn on.. If you're fan is always on, you can try grounding the signal line to keep it off..

 

Both S4 and S5 have an ECU thermosensor mounted on the back of the water pump, directly below the alternator.

The S4 has a thermoswitch for auxiliary electric fan on top of the thermostat housing.

The S5 has a thermoswitch for auxiliary electric fan next to the ECU thermosensor on the back of the water pump.

 

Gentlemen, thank you very much...I'll get right on it...

 

how much is one of those thermosensors?

 

But not all have an auxiliary electric fan, right? I mean, I'm pretty sure mine doesn't.

 

Yeah, it was only optional on some models.

 

SO what exactly does that thermosensor do? I left mine unplugged for a while on my 88 SE since I used the spot for a aftermarket gauage.

 

Which one?

 

The on the back of the waterpump housing. The green plug.

 

It tells the ECU the coolant temp. Leaving it unplugged would be a foolish thing to do.

 

my car woudln't even start when I left it unpluged once.

 

I left it unplugged for a good month or two without any ill effects. I checked too but it ran fine.

 

the ECU will use a stored signal in memory if the thermo sensor signal is disrupted or out of map tolerances...if the signal breaks while driving, you'll know it...it's hard to believe you didn't notice any difference, Digi7ech, my car ran pretty crappy when the signal failed...I'll bet your engine was not running as efficiently as it should have...

 

The stock computer will default to a setting of 80c if the sensor is unplugged/way out of tollerance.

 

I knew someone would have the books in front of them and produce the temp number, LOL, thanks, White FC

 

Well the thing was an 88 SE with 150k on the engine. It pulled a 17.4 at it's prime. So no i did not notice anything! lol

It blew a coolant seal in the front rotor anyways 4 months ago.

Now I'm selling it as a parts car. hint hint!

 

THERMO SENSOR COST THE ORIGINAL FROM MAZDA 40$.

 

what about 2 on the back and one on the top?

 

Huh?

 

one looks like a thermo sensor the other looks like a thermo switch that belongs on the rad. jspec thing maybe?

 

You need to be a whole lot clearer. I have no idea what you're asking.

 

heres a couple of pics. there was no conector on the harness I got for it. and I did not see it on the FSM wiring diagram. so I either need to break in to the harness and find the missing wires or I can leave it as extra. the engine is a late 88 jdm

 

well it seams there is a problem with posting pics right now will try again latter