The instruments computer reads the coolant temperature sensor 40 times a second. The voltage on the sensor is high for about 4-6 msec every time it is read. Therefore the sensor voltage can not be measured with a normal voltage meter. One would need an oscilloscoop or a (fast) voltage meter with a maximum voltage function. It is calculated that there is a 230 ohm resistor connected between 5V and pin 8 in the instruments computer.