Temp gauge not working.

[MiniC]

Hey zone just done loads of work on my 325i and have replaced the cambelt /coolent etc the cars running well but I don't know how hot it's getting as my gauge isn't working. Any ideas? Also if it matters my k6 and k1 relays are missing.

[Brianmoooore]

Relays K1 and K6 are for the auxiliary electric cooling fan fitted as part of an air con system.
First thing to do to sort your temp. gauge is to unscrew and take apart the C101 20 pin engine loom plug and socket, next to the fusebox.
Take a piece of wire, earth one end of it (rear bonnet locating bracket is ideal), and push the other end into pin 4 of the half of the C101 that is still attached to the car.
Turn the ignition on and see if the gauge remains at zero or goes to full hot.

[MiniC]

By the look of it it's staying at 0

[Brianmoooore]

If that is the case, the problem is with the instrument cluster, or the wiring between the C101 and the cluster.
Did you disconnect the car battery while working on the car?
Are the service interval LEDs working as they should, including resetting propery?

[MiniC]

I did disconnect it as far as I remember. And it seems all of the instruments on the cluster are good. Fuel/light other lights etc. Only the handbrake light doesn't go off unless you have the car running.

[Brianmoooore]

Are the service interval LEDs working as they should, including resetting properly?

[MiniC]

No service leds were on when I checked.

[Brianmoooore]

Time to open up the cluster and see what's going on with the batteries on the SI board/

[MiniC]

alright ill get on that. what am i looking for if anything? also the cars been sat for probs 15 years so batteries maybe dead?