temperature switch relay NLA

[alexg]

Hi:
Tried to order part 61 31 1 459 009 from Euro Motoelectrics and tried the stealer as well. NLA! MAX BMW has it available but I ordered a "previously owned" from e-bay to try.

In any case, I am wondering if there is a source for repairing these relays, as they have some electronics inside that control fan and overtemp light.

How do I know it is the relay: fan is always on, even at startup cold, the resistance of the temp sensor is in the right range (2200 ohm), and removing the relay stops the fan. I must assume it is the relay, unless there are other opinions.

Thanks for the help,

Alex

[daveson]

If you remove the temperature relay you can check for continuity between pin 15 and pin A2. You should not have continuity, if you do, that looks like the contact is stuck closed.

If you don't have a multimeter, connect the relay to a battery, positive to pin 9, and negative to pin 31. Then with a jumper wire between 31 and E for the briefest moment, you should hear a click from the relay. If you don't hear a click, again that sounds like a stuck contact.

I spose a short in the wire from the temperature sensor to pin E is another possibility so might be worth a look.

[Laitch]

How do I know it is the relay: fan is always on, even at startup cold, the resistance of the temp sensor is in the right range (2200 ohm), and removing the relay stops the fan. I must assume it is the relay, unless there are other opinions.

You might consider cleaning a particular frame ground connection as mentioned in this bulletin concerning early models with that condition.

[alexg]

Thanks for the tip Laitch; I will check the ground, but I cleaned the thing good when I replaced the battery a few month ago.

@ Daveson: I checked if the relay and is not stuck. Checked the resistance of the temp sensor terminal, and is 2200 Ohm, which for a cold engine is normal.

Will report when the new old relay arrives.

Thanks,
Alex

[alexg]

Installed a new used relay; all worked as designed. I noticed that the fan came at a slightly lower temp than with the original relay (when it used to work). Thanks for the suggestions. Now that I have a faulty and a working one, might do some troubleshooting to see what is the component that failed; I bet it is not the IC but some stupid resistor or one of the small power transistors. Will update if I find anything.
Alex

[sebas2357]

Glad to hear everything's back to working as usual.  Keep us posted on what failed within the relay, would be interesting to know!