Temp sensor/sender question

[NHbmw325I]

I have an issue after doing my engine swap. The temp gauge on the instrument cluster pegs to red as soon as the key is turned. is it the blue sensor or the black one that controls the gauge reading? I have a 325 so has 2 sensors on the cylinder head.


thanks!

[gpelite]

I always assumed temp readings came from the rad coolant temp sensor... Actually Im pretty sure. Thing does go bad or in my case a light film of dirt was on it from the years of use. Cleaned it and suddenly was far more accurate.

[flyfishvt]

I always assumed temp readings came from the rad coolant temp sensor... Actually Im pretty sure. Thing does go bad or in my case a light film of dirt was on it from the years of use. Cleaned it and suddenly was far more accurate.

Temp readings come off the sensor in the cylinder head. 96-99 cars have one that sends a signal to the dme AND the cluster gauge. 92-95 cars have 2. 1 for the dme and one for the temp gauge. The blue one in front is for the dme. The connector for that one should have a patch of blue on it. The black one next to it is for the cluster gauge.