Hello and thank you for your post. I am a master certified GM tech, with 15 years Saturn experience,and can help you to resolve your issue.
which computer did you replace? the engine or the body control module? (ecm or bcm)
have you installed a scan tool to read engine coolant temp as it is being reported by the sensor?
I believe at this point that is your only option moving forward.
if you do not have access to one, it is time to take this to a mechanic and see if the sensor is reporting properly when the gage goes off
I replaced the ECM and I have a scan tool but if there are no codes to read the check engine light is out. I will look at the BCM to see what is going on there.
the ecm gets the coolant temp signal from the sensor and then sends a signal to the cluster and to the body control module which also communicates with the cluster
according to my info, the bcm is not in the loop for the coolant gage but i doubt that is correct as the bcm really controls almost everything on this car
so you MIGHT have a bcm issue but I can't say
on your scan tool, read the coolant temp sensor reading when the gage is reading badly and if the coolant temp reading is also bad then you have an issue with the sensor or the wiring
Let me check this out and will talk later
tip: if the sensor reads about-40F then it has an open wire
if it reads about 290F then you have a short to ground across the signal return wire.
so check that and let me know what you find
The problem was the Themostat it was bad and the computer was setting a fault code of dropping out at 174 degrees. The dealer had to find the problem. It was not the gauge computers or anything wiring related.
ok. glad you got it figured out.
as I said before using a scan tool was required to solve this. ( to see what the temperature was being reported by the sensor)
I have a scan tool it was not showing the fault. What they did was hook it upto a laptop and watched it work. That's when they figured out that the thermostat was bad. My regular scan tool did not show this message and he informed me it wouldn't.
Thanks, XXXXX XXXXX to be a bigg issue with Saturns he said. The Ion, Sky and the Vue