Good morning/afternoon everyone. I recently purchased a 06 Gs300 and some things have started to happen here and there but I am having issues the coolant and fuel gauges are inaccurate it started with the coolant temp gauge reading cold all the time when it’s at temp. The fuel gauge was never accurate since I got it but it’s been getting worse now when it’s full it only marks a little bit above half. I read somewhere to fix the gauge manually and when the car is off the needle slowly falls from E same with the coolant gauge. I’m at work currently but I used this as an example the white lines are where the needles will be if I try resetting them on E and let the car sit for awhile. The yellow lines are the lines are where they will be once the car gets up to temperature.

 

Have you put the car on a scan tool and tested the coolant temp, and fuel levels on the scan tool itself? I would try that before tearing apart and adjusting your needles. Maybe its another issue causing the ecu to read funny. For instance if the scan tool shows the temperature is low, and the instrument is low aswell then it could be the temp sensor. This is why using a scan tool to verify the ecu is the same as the instrument cluster. If the temps on the ecu are different then the cluster then I would suspect the cluster

I would also check for voltage issue, make sure alternator is producing proper voltage.

 

That's a common gauge cluster we have replaced in the past for needle issues. If your diagnosis leads to that, we can set you up with a replacement.

 

I like that there are people who specialize in our old cars and you always make courteous posts.