[AstraMX]

Main issue:

• Car starts, runs OK, warms up, but NO temperature is shown on Instruments temp gauge. Car gets visibly hot, heater works. Everything else works, but temp gauge never increases and radiator fan does not turn on even at 95°C.
• Before the Temp gauge issue not showing temperature, the fan was working OK.
• Fan turns on when Thermostar sensor is disconnected.

Image showing Coolant temperature working OK but FAN not turning on at 91°C

Diagnostic:

• OPCOM on Engine output values shows Coolant Temperature going UP when engine is running, and DOWN when stopped. No FAN is coming up when reaching 85°C to 95°C and Intrument cluster temperature gauge doesn't move at all.
• OPCOM on Body and Instrument diagnostics, can increase and decrease the Temp gauge physically and it's working OK. For this issue, the output values that can be read are this ones:

- Image showing that Temp gauge can be increased/decreased with OPCOM diagnostics:

Body and Instruments fault codes shows ECT circuit low and high input (165 & 166)

Already swapped:

• New Thermostat and Sensor
• Bought a new Engine cooling module for around $160 USD and I just found out my car has NO Engine cooling module behind the front bumper (Maybe previous owner took it out? I've been owner for 8 years and no previous Cooling Fan or Temperature issues other than replacing thermostats)

Image showing no communication to Engine cooling module:

I need help, I'm lost I don't know how to go from here and car has been parked for almost 4 months now :'c

Thanks...

 

[Ayresyy]

These issues could be signs of the ECU failing.

 

[Jaybnewcastle]

On later astras there was two coolant sensors one on bottom of radiator drivers side maybe the same on yours

 

[AstraMX]

On later astras there was two coolant sensors one on bottom of radiator drivers side maybe the same on yours

I'll check this, thank you

These issues could be signs of the ECU failing.

Wouldn't be bad to take my ECU for some visual check, thank you

 

[AstraMX]

Ok, so far I got an update...

The issue seems to be within the wiring to the instrument panel, the wiring to the engine loom is OK.

I don't know the exact point of failure in the wiring but I'll try jumping from engine loom to instrument panel tomorrow....

So far, temp gauge gets no reading when connecting a 250ohm resistance to the temp connector, but car runs good.

Anyone has instrument panel diagrams?

 

[AstraMX]

Changed the instrumnets with a working used part and all has been fixed