Does your 90 has the gauge connector behind the glovebox? Then it should have the connector for the temperature sensor too. Search for it below the left front light. It has two blue/striped wires. There goes the sensor. The other features don't need extra sensors.
Greetings
Is there anybody interested in a clinometer? I have one of the colored version for sale with the temp sensor included. I am located in Germany. Just drop me a message!