Temp Gauge 2005
 

My 2005 Malibuhttp://images.intellitxt.com/ast/adTypes/icon1.png Maxx LT's temp gauge stopped working last night. The fan still seems to be working when it needs to and the air is still hot from the heater.

I have 5V across the pins to the ECT. Is this the same sensor that runs the gauge? Or is there a separate sending unit? If so where is it?

data from the ect sensor is read by the ecm and sent via serial data lines to the instrment cluster.

a fault in the ect sensor should default the temp guage to 100'F and set dtc in the ecm. What is the guage reading when the fault occurs?


key on engine off, you should have 5volt on the yellow wire.

grd is provided on the orange/black wire via the ecm.


Disconnecting the harness to the ect sensor should make the guage read max cold with key on engine off. jumpering the connector terminals should make the guage read max hot, koeo.

I had the 5V and ground KOEO. The gauge is bottomed out no movement. It just threw a code I still have to read. I am betting on the sensor being it.

The engine constantly runs as if it is cold, but the fans run too. I have heat inside the car as well.

Jumping the wires causes no change. Neither does any disconnect that I can easily do.

I just replaced the sensor and no change at all. Any further hints? I am working blind without a manual or diagram on this car.

if the guage is bottomed (reading cold) and you have already replaced the sensor; the wiring is open.

Grd the yellow wire and see what the guage does, it should go full hot. If it does 5 volf ref wire is good and the grd wire is open. Check the grd circiut again.

if your sure the grd wire is good; connect everything back together and observe the temp reading with a scan tool. If its reading ok with the scan tool, the stepper motor in the ipc (cluster) could be bad. Do the guages do a needle sweep at key on?

Well, it seems fixed now. I had to disconnect the battery. Then a 15min drive. then shut it off and turned it back on and somehow it was working. Hmmm.... a reset period maybe for the PCM?

Very useful info. Hope to see more posts soon!