temperature gauge problems

[Omega2.5]

Hi all, I have a 1998 Vauxhall Omega 2.5.t/d Elite, temp gauge not working, I have had the sensor changed, but gauge still not working, before I change the dash cluster is there anything else that I can check, I also have a problem with he interior light, when the doors are closed it stays on at half brightness, I am wondering if both of my problems are connected, any help would be gratefully received

[GreenV8S]

No idea what the circuit is for either of those, but presumably the light has more than a simple on/off ground via the door switch. Is it possible that these circuits have a common ground and it isn't a very good one?

[Omega2.5]

Thank you for your reply, I think you are correct in suspecting a dodgy earth, problem is where, I wondered if the time delay that turns the interior light is at fault, but cannot find any information on which device controls it

[GreenV8S]

Google suggests that some Vauxhalls operate the courtesy light through a relay which has the timing function built in, but I also saw a comment about the Omega/Carlton suggesting that it has an electronic circuit built into the overhead light fitting.

[Penelope Stopit]

Earth fault causing both problems is a near on zero chance, if it was the case of an earth fault at the cluster there would be numerous faults
The interior light will have a delay unit built into it or fitted elsewhere, if the delay is in the lamp you could disconnect or you could test the door switch signals at the delay unit and light and if all is ok try another light, the same goes for if the delay unit is fitted somewhere else....disconnect the delay and see what happens and then if there is still a problem you could check the door switch signals to the delay and light and go from there

As for the temp gauge fault, you need to find out which is the temp sensor for the gauge, there will possibly be 1,2 or 3 temp sensors fitted at different points around the engine, once you know where the sensor for the gauge is fitted you can unplug it and if it has 1 wire to it you can connect to earth and watch the gauge to see if it moves up, if there are 2 wires to the sensor the chances are that you can link them together to see what happens at the gauge, the chances are that 1 of those 2 wires will be an earth and the other 1 will go to the gauge, google for a diagram so that you can be sure you are checking it correctly

Now if you are comfortable with the above tests and have carried them and the gauge hasn't moved up, you need to check the wire that connects the sensor to the instrument cluster, remove and unplug the cluster, unplug the sensor, now carry out a continuity check between the sensor and the cluster, if all checks out ok....there is a very good chance that the cluster is at fault and you will need a professional to check the cluster.....I could go through a cluster test with you but there are too many scenarios that may break something if a test is carried out through an electronic circuit in the cluster

[Omega2.5]

Hi All. thank you for your suggestions, I will try changing the interior light, have already had the gagrage change the temp sensor, so it looks like the cluster is the next step, thank you for your help.