So what is the indications of the temp guage not being accurate?
Here is what goldwingdocs.com sayz about it. If this isn't your symptom, then continue along the lines of adjusting just the fuel gauge,
If you have a GL1000, GL1100 or GL1200Std Goldwing with mechanical (not electronic LCD) temperature and fuel gauges, you've had this problem. Or...you will. It's only a matter of time. You'll start noticing that your temperature and fuel gauges are reading off the scale - the temperature is in the red, and the fuel shows full. The only thing is, the bike isn't overheating, and you know you've only got a quarter tank left. Or...even worse: your bike is operating normally, and suddenly your temperature and fuel gauges just turn off, and look like the picture above. How much fuel have you got left? You'll have to guess!
What's causing it? A faulty, worn-out 7 volt voltage regulator. Behind the fuel and temperature gauges is a special voltage regulator that turns your motorcycle's normal 12 volts into the 7 volts on which these two gauges run. When it starts to fail, it typically starts doing so intermittently. Left in a failed state, it can cause damage - allowing a full 12 volts into your temperature and fuel gauges, destroying the delicate coils inside! That gets expensive, requiring the replacement of the entire center gauge cluster!
Now let me state one thing: If one
of the two gauges is working normally, and the other is not, then your problem is not
your 7 volt regulator. But if both of them are not working correctly - it's time to replace that regulator. The symptoms of a failed 7 volt regulator are both fuel and temperature gauges reading high, or both reading zero, and it commonly happens intermittently for a while before complete failure.
Ohhhhh, 1500! Ummmm yea, thin this definitely ISN'T your problem