temp gauge won't register, footwell connectors?

[fronton]

My M3's engine temp gauge has not worked since before I bought it. I think the previous owner messed up the wiring because there was about 5lbs of crap connectors for the sound and alarm system that I took out of the footwell alone! Anyway, I didn't care much while the s14 was in there but I have now done an s38 swap and need to more carefully monitor the temp since it generates MUCH more heat and my cooling system is custom.

When the key is turned to Pos II, the temp needle nudges from rest to very cold then never does anything else regardless of how long the engine has been running. It does not jump around, and I have never seen it above cold with either engine in it. I have put in new temp sensors on the coolant rail and it did nothing. Yes, I get heat threw my heater, so its bled correctly.

I just tried another e30 M3 cluster as well as a '89 iX cluster and neither registered any temp gauge reading, same story every time.

SO... there must be a breakdown elsewhere. I'm hoping there is a loose ground nut or something but can't find one.

Could any of the following disconnected plugs be related? There are five. three in my hand, the white plastic square in the middle with two prongs and the bright orange. None of those are plugged in and I don't know what they are suppose to connect to since I can't find 'mates' for them.



This one is for the 13 button OBC correct?:

[jlevie]

The temp sensor wires run through C101 to one of the connectors for the cluster.

The wiring diagrams from http://wedophones.com/BMWManualsLead.htm will help in determining where the problem is

[Unearth078]

that one that you think is for the obc, looks like a aftermarket radio connector from a older kenwood.

[ezlnh8u]

I have a simmular issue with my temp gauge, i replace the speedo on my cluster, before my temp gauge read perfect, but now, after installing the new speedo, the temp gauge does not pass the end of the blue line, i never touhed the temp gauge, so i am not sure what might of happened, the solder is intact on the back as well. any sugestions?

[fronton]

that one that you think is for the obc, looks like a aftermarket radio connector from a older kenwood.

Thanks, I'll junk it. The car came with a ton of 80s sounds crap. I think the heat unit was indeed kenwood but it may have been jvc. real lame carbon trim faceplate. I now have BMW's blank plate on. MUCH nicer.

[fronton]

All sorted out. The connection was not correct between the X20 and C101 pins. Thanks or the tip jlevie!