need help! electronic issues

[bullyd]

hi to all! been away due to computer troubles but now im back with yet more car troubles,
my temp is reading -37c (changed temp sensor to no avail)and my cruise control packed up on the same day! could this be linked or coincidence?
any ideas on what to check with regards to temp sensor?
thanks in advance

[bullyd]

;) bump

[wingman]

bump x 2 he he he. Hope this keeps it fresh bullyd. Sorry I can't help you though.

[Phil Sanderson]

http://bmwe32.masscom.net/ Go to "Fixes/Electronics/-30 . It may be your problem.

regards
Phil

[bullyd]

thanks for the link phil but i think ive found my problem! the plug for the sensor looked like a wire was hanging by a thread and closer inspection showed it was! i thought about cutting the wire further up and joining a new plug but the internal wire has gone black? ive cut about 3 inches off the wire and its still black, does anyone know what could have caused this? if its just age can i follow the wire into the nearest good part of the loom and solder in a new one? or will doing this give me false readings? thanks

[SRR2]

Copper wire can turn black and still function, though it's not a desirable situation for sure. The black appearance can be caused by components of the insulation deteriorating and migrating and acting on it, causing oxidation or other chemical reaction over long periods of time. Exposure to temperature extremes and other environmental factors doesn't help either.

You can replace parts of that harness with copper wire. The sensor is a thermistor so it's not sensitive to wire type like thermocouples can be. However before you do that, you should check end-to-end continuity with an ohmmeter to prove that the wire is actually the problem.

Considering the 'dry circuit' nature of the thermistor, I'd suspect a corroded connector somewhere before the wire itself. With the low currents and voltages in the circuit, it doesn't take much deterioration at all in a connection to cause trouble. And we're talking about something that's 16-17 years old, so this kind of problem should be expected.