Hi chaps.

Mk4 fiesta. Coolant temp sensor for the dash is a 1 wire type. 12v sent from the dash to the sensor, and the sensor varies resistance depending on heat and earths to the engine block.

Anyone happen to know if it changes the flow of current or voltage?

Thanks

 

Your coolant temp sensor works on the earth side, then the other side of the temp clock as an ignition feed to it, so when you disconnect the wire off sensor and put it to earth it should go to the top.
As your question : as the coolant temp increases, the resistance value and the signal voltage decrease.

 

I understand that the ign 12v comes from the dash. What I was asking is weather the sensor (thermister) changes the voltage it lets through, or the current. I'll get a volt meter on it I suppose. Was just being lazy!!

Matt

 

It's the resistance that changes, this in turn will effect both voltage and current (ohms law).

Martin

 

Of course.... Thanks.