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[Clarkey]

Hey all, not been on here in some time.

I have recently put my Omega back on the road after being parked up a number of years. It is a 2001 3.2 Auto. I just fitted a new thermostat but still have no engine temp reading on dash. I plugged in tech 2 to check live data and did an actuator test while I was at it. Engine at operating temp reading 90deg C in engine ECU live feed. When I check engine temp from instrument feed it reads 60deg C at operating temp. I know there are 2 sensors on coolant bridge at back of engine. I took wire off single contact sensor as I thought this was for instrument temp feed and put it direct to earth which turned on engine overheat light but did not move temp gauge. I also tried a replacement dash and got same result. Does single wire sensor simply operate overheat light or does it supply engine temp signal to dash as well?

Thanks in advance,

James.

[Doctor Gollum]

That is the dash temp sensor. The fact it grounds the light on suggests the wiring is sound... Doing this should also move the gauge. Did you try with the ignition on? If it still doesn't move, then a new sensor is probably on the cards with the following caveat...

Could also be that the gauge itself is stuck... A gentle tap of a couple of potholes may be enough encouragement.

[Clarkey]

That is the dash temp sensor. The fact it grounds the light on suggests the wiring is sound... Doing this should also move the gauge. Did you try with the ignition on? If it still doesn't move, then a new sensor is probably on the cards with the following caveat...

Ignition was on when I grounded wire. Was surprised gauge did not move yet overheat light on when I grounded wire. When I performed actuator test with Tech 2, needle went to max and light came on. As engine temp showed 60deg on instrument data feed it was not registering hot enough to move needle.

Could also be that the gauge itself is stuck... A gentle tap of a couple of potholes may be enough encouragement.

I've tried a couple of "gentle" taps when driving at the beginning. Looks like replacement sensor is the way forward. Before I fit it can anyone tell me the correct code index for the instrument panel for my machine?

Thanks for reply Doctor G

[Doctor Gollum]

If you have access to the live data, is the ECU seeing the coolant temp

[TheBoy]

ECU and dash sensors are separate on the 6 cylinder ones (not sure about 4, as never owned one).

Ground the single wire for longer - the dash gauge is massively damped (30+ seconds) - to see if it moves needle.  If it does, replace the sensor (or check it for a large build up of crud, which if it has, this will likely also be present throughout the coolant system, so you know what you need to do!)

[Doctor Gollum]

ECU and dash sensors are separate on the 6 cylinder ones (not sure about 4, as never owned one).

Ground the single wire for longer - the dash gauge is massively damped (30+ seconds) - to see if it moves needle.  If it does, replace the sensor (or check it for a large build up of crud, which if it has, this will likely also be present throughout the coolant system, so you know what you need to do!)

4 pots have the same set up although the coolant 'bridge' connects one side of the head.to.the other rather than joining two heads

[Clarkey]

ECU and dash sensors are separate on the 6 cylinder ones (not sure about 4, as never owned one).

Ground the single wire for longer - the dash gauge is massively damped (30+ seconds) - to see if it moves needle.  If it does, replace the sensor (or check it for a large build up of crud, which if it has, this will likely also be present throughout the coolant system, so you know what you need to do!)

Thanks TheBoy. You are the man. I was over thinking this. New sensor ordered.

[Clarkey]

Update on this. I replaced engine temp sensors on coolant bridge (did both while I was at it) and still have same issue. At operating temp (engine ecu live data 95 deg) the live data in instrument reads 65 deg for coolant temp. Same thing with spare dash I acquired. I then let the engine cool and rechecked. Engine temp was 25deg in engine ecu feed but reads steady 50deg in instrument live data. When I ground single wire for temp gauge, overheat light on but temp reading on instrument live data is 0 deg. What am I missing?

On another note the rev counter was reading too high. I had to reprogram code index on instrument from 12 to 7 to have it register correctly. I have no idea how code index changed but wonder if some time in oven after respray could have caused issues. Am open to suggestions.

J.