I recently acquired a 2001 slk230 with 105k miles on it as I've stated in the intro post I made.
I have been doing a little bit of maintenance on it, to include changing the fan control module which was faulty and some other smaller things, everything was going smooth as butter until yesterday when I went to reconnect the negative battery terminal after I've disconnected it, like I always do if I am messing with anything electrical, but this time it was to see if I could clear the CEL after replacing my O2 sensor.
So some background first. I have previously disconnected my negative battery terminal to change out the fan control module which fixed my fan not working, obviously doing that required me to enter my radio code which I have and has worked successfully.
Today however I disconnected my negative battery terminal to do some work and when connected it back up to take the car on the test drive two weird things happened.
the cooling fan doesn't engage anymore, however the low coolant light doesn't turn on like it did with the previous faulty unit and when I turn on the AC the fan does turn on but weakly.
Does that mean my module is going out again?
This time around when I enter my radio code the radio doesn't accept it anymore when I know the same code has worked previously without any issues not even two weeks ago? Now, the previous code that I have entered was one that was written down for me by the previous owner, this one is off a little silver card I found in the car, and I can't for the life of me find the one the previous owner has written down for me. I have ordered a set of radio removal tools just to compare the serial numbers I have my my silver card to the one on the radio and eliminate that issue.
My question is, do these cars have some type of a fail safe fuse or something that when disconnecting and reconnecting the negative terminal can make it blow and therefor causing said problems? And also lets say that my fan control module is going bad again, has anyone just bypassed the stock one and created their own circuit with a custom thermal switch? I am asking cause spending $150 bucks every 2 months on this module could get a little costly at the end of the year hehe.
I have been doing quite a bit of searching on the forums, but haven't really come up with a solution to my issue, any insight would be greatly appreciated.