Does anyone know how these are tied together? I tried searching but didn't come up with much. The tstat housing seems to have 2 sensors on it: one in the front (single wire) and one in the back (more of a plug). The gauge on the dash does not read the same as the ecu, it seems to somehow be smoothed out unless temps are 230°F or higher.

I'm kind-of thinking the dash gauge is connected to the sensor at the front, and the ecu is connected to the sensor/plug at the back, but it's an educated guess at best.

 

Yeah, the dash gauge isn't a linear gauge for sure. It's more of a dummy gauge to alert the driver when the car is overheating.

How exactly it's accomplished or wired, I'm not sure. I'm sure some electrical expert in here can shed some light on the subject.

 

The single wire sensor is usually for the dash guage & the two wire sensor should go to the ECU...That's what past experience tells me, I could be wrong though.

 

Yes, that is correct.

 

Yes the front single wire is for the guage. If you have issues with the guage not working properly, check the contact on the sensor, it gets crudded up by any leaks from the hose above.

The rear sensor is for the ecu, IIRC its resistance goes down with increasing heat, not sure about the change to 0-255 for digital inside the ECU though

Milburn

 

Ok, that makes sense.

Do VIII's and IX's read differently at these two points? The IX has a channel that connects the tstat housing with the outlet pipe benieth it. The VIII's don't have this, and it seems like when logging them the coolant temp will go up while doing pulls then immediately go back down. IX's don't seem to do this. Could this be why (or part of the reason) some people say that the IX head has better cooling properties than the VIII?