M42club.com - Home of the BMW E30/E36 318i/iS

DISCUSSION => Electrical => Topic started by: AlpineE30ic on November 18, 2013, 08:11:45 AM

Title: 1992 E30 M42 Temp Sensor Locations??
Post by: AlpineE30ic on November 18, 2013, 08:11:45 AM

Im looking to find the exact locations of the engine's temperature sensors?? I can't seem to find anywhere a photo of the brown temp sensor which is what sends the reading to the actually temp gauge..?

I just replaced the SI batteries in the cluster but when I turn just my ignition on, the temp gauge spikes to full red, and then back to the off position when the car starts...then it does nothing.

from what Ive read, there are 2 or 3 sensors/senders? Can anyone confirm this?

thanks!!

Title: Re: 1992 E30 M42 Temp Sensor Locations??
Post by: deansweet on November 18, 2013, 10:25:37 AM

There are two temperature sensors, both on the intake side of the head. The sensor closer to the front sends the signal to the ECU, while the other sends the signal to the temperature gauge. They are situated beneath the intake manifold. Hope this helps. Have a look on www.bmwfans.info or www.realoem.com to get an idea.


http://bmwfans.info/parts-catalog/E30-2-doors/Europe/318is-M42/M/jan1991/search?s=temperature

(http://ills.bmwfans.info/py.png)

Title: Re: 1992 E30 M42 Temp Sensor Locations??
Post by: AlpineE30ic on November 18, 2013, 10:46:07 AM

Thank you! this is a huge help! - 10 years of bmw ownership and this is the first time I've come across bmwfans site...awesome stuff

thanks again

Title: Re: 1992 E30 M42 Temp Sensor Locations??
Post by: DesktopDave on November 18, 2013, 05:12:20 PM

That sensor is pretty easy to get and and test. Between the sensor pin and a good ground (like the cylinder head) you should see high resistance when the engine is cold (something like 9K ohms) and low resistance at operating temps (only a few hundred ohms).

Your problem might also be a bad temp gauge or burned trace on the board too. I've seen both.

Did your battery swap repair the service lights?

Title: Re: 1992 E30 M42 Temp Sensor Locations??
Post by: AlpineE30ic on February 11, 2014, 09:28:13 AM

would a bad sensor (the one that sends to the ECU as you mentioned above) effect the read out at the temp gauge?

thanks

Title: Re: 1992 E30 M42 Temp Sensor Locations??
Post by: DesktopDave on February 11, 2014, 03:55:11 PM

Not that I'm aware of. I'd suspect a bad contact, broken wire, damaged cluster driver board (the circuit board/back panel) or gauge. That sender is just a resistor - it can be easily tested with an ohmmeter (or a multimeter on the ohms/resistance setting).

Well, with the intake in the way it's not really easy to test, but you get the idea. Both coolant sensors and the air temp sensor all share the same test specs. Resistance should be very high when cold, lowering as the sensors warm up. When cold, you should see high resistance (>3Kohm). When warmed up, you should see far less, like 300 ohms or so.

The sender uses a brown/violet wire...it comes through the C101 connector (big round one at the firewall). From there it goes to the cluster connector C1, pin 26. The gauge is powered from the SI board via terminals 1(+) & 12(-), it converts the sender resistance to a needle movement.