(See my previous threads on my wifes R55)

Last year i found no compression in cyl 2, and replace exhaust valves. Since then we have had no heat in the cabin, and watching the temp gauge on torque app, it never gwts above 140F.

I have replace the thermostat 2x (once before the head work, and in hindsight P173b has never gone away), total of 3 thermostats, new radiator, new crossover pipe, just did the waterpump a few days ago. I bleed the system till no air comes out. The car comes up to temp in the shop and the thermostat stayes open. I have heat on the test drive, then never again.

No air, only coolant comes out of the bleeder, no leaks, holds pressure perfectly. I have used air to push all old coolant from the heater core, and filled it before hooking the hoses back to the thermostat.

Again i am very confident there is no air, no leaks and coolant moves.

I am reading that the thermostat is electronic, can a bad module keep it open? My service light will not reset. I have chaned the brake sensors and reset it all includint the mini on the lift light, yet they all come back.

I did get the card in the mail about extending the warranty on a bad BCM for lighting, and other functions. That would explain the service lights, but i have 172k on it, so its well out of warranty.

Does the DME control the thermostat? Have i been maybe throwing darts and chasing my tail on this issue?

Thanks.

 

I just looked on newtis.info and found the rear connector controls the "charastic map thermostat"

I cant seem to find what voltage is supplied to open/close the thermostat.

Id love to see if this has been the source of my woes.

Can someone supply the data for these pins for open/close?

 

I just looked on newtis.info and found the rear connector controls the "charastic map thermostat"

I cant seem to find what voltage is supplied to open/close the thermostat.

Id love to see if this has been the source of my woes.

Can someone supply the data for these pins for open/close?

 

Going to embarrass myself. I had to 2 radiator hoses that go to the radiator from the t/s on backwards and had trouble that you describe.

 

I feel like an idiot, i checked the hose diagram, yup reversed.

All heat back, light off, sanity restored (kinda)

 

It happens, glad you got it fixed.