what gives the stock temp gauge its signal?
 

the reason I ask this is because the stock water temp gauge on my car(after my TII swap) goes all the way to H with the key in the "ON" position, and as the car warms up(the only 2 times it started :( ) it moves down a little. almost like the gauge is on reverse???

I thought the little plug on the bottom of the rad that the two wires went to controlled it, but I tried switching those, and same thing happens(maybe I just screwed up and put them back in the same place[I tried this twice]:D?)

and the main reason I'm concerned is because I think my ECU is screwed up by it, and causes my car to run overly rich(when it ran those 2 times :( ) like it's still on warm up mode, or whatever its called.

I'd really appreciate any input. thanks

-travis

the gauge reads off the water temp sensor which is right below the oil pressure one. under the oil filter. the sensor is tiny

it gets its signal from a small gnome who hangs out in the coolant

Water Temperture Sender Unit found under the Oil Pressure Sender Unit.:)

hmm...... any ideas why the gauge is screwing up so badly then? I'm almost 100% sure the wire is plugged into that (I know what you're talking about)

Well yes, If It wasn't plugged In, you wouldn't get a reading.:D

If I had the same problem, I'd disconnect the wire, wipe down the contact point of the Sensor and Wire. Give It a go...If nothing changed, I'd check the solder joints behind the Instrument Cluster. Still the same, change the Coolant Temperture Sender Unit. Good Luck...

stick a couple of dollars into the radiator, that should appease the little guy :D

What sensor is on the water pump neck then? I always thought that was coolant temp...

coolant temp is the same as engine temp

that is the coolant temp sensor for the ecu

Just to clarify Scott's answer, the sensor on top of the thermostat housing on a S4 is the electric fan's temp switch; the sensor on the back of the water pump underneath the alternator is the ECU's coolant thermosensor. ;)

There's a good pic of the temp gauge sender on page 106 of the Haynes manual (Fig. 10.1).

Im pretty sure its beside the oil pressure sensor, not under it ;)