N65 Cycle Control Module- '97 C230

[PHAEDRUS242]

So during the 60K I did yesterday, I show a current fault in my AAC for "N65 Cycle Control Module". I'm getting together with one of my techs later on to assess this, but I was hoping to get some suggestions from the community at large. I don't have any real symptoms present, but knowing the code is there is aggravating me. Anyone familiar with this? I checked STAR Finder and ther wasn't even a location listed for the part.

[MrCjames]

The cycle module is responsible for controlling several different items, controlling the auxiliary fan is one of its operations. The module may be conveniently placed in the fuse box assembly, slides into the side and has the appearance of being part of the box. What code did you retrieve from the system?

[PHAEDRUS242]

The Code is B1421 Cycle Module N65.

[MrCjames]

You may want to double check DTC's in the Air Conditioning control unit as well. The code refers to a K2 serial interface problem. Go to N22 (A/C Pushbuttons) and on the R/H connector KEY-ON socket 10 to ground you should have >.300 V. I would imagine if the voltage is correct than N65 may not be capable of processing the info from N22, you may need to check the voltage input to N65 to be sure.

[PHAEDRUS242]

Thanks for the info. My techs and I will be tearing into this bad boy later this evening. I'll post the results of our little adventure.

[PHAEDRUS242]

Alright, it took a little electrical testing and a whole lot of reading, but I have the definative answer to the elusive N65 problem.

The build date of my vehicle falls at a time when the M111 recieved the newest available electrical fan. The ME and the AAC modules are still old versions. Because of this, the code is totally invalid and should be ignored (direct statement from MB). I imagine there are very few cars in the world that have this specific lineup of modules, so it probably explains why I haven't seen this on a 202 before. In later variations, the cycle module was tied into the ME via the CAN databus and would throw a check engine light when it failed. This is now quite obviously not the case for mine. This also explains why, despite showing a current fault, the fan still continued to operate normally, it never ran hot and the A/C worked almost too good in the hot, humid midwestern climate I currently enjoy.

One peculiar thing is, as soon as I entered the "activations" screen on the SDS, the fan kicked off. You are also unable to perform any sort of version coding for the fan, both because of the older AAC module. This was all located through MB literature I spent too much time reading through last night.

So the good news is, everything on my car is now in perfect running order, save for some normal MB seepage from the diff and one tiny drip starting to form from the pinion seal. This will be dealt with accordingly on Tuesday night of next week. Thanks to MrCjames for the assist on this one.