Suddenly the front lights do not work, though the CS2 is set to have them on. In looking at the parts diagram I do not see which part is actually creating the light and how to get to that part. Also, I don't see how to open the locomotive so as to get to that part. Appreciate advice.

Regards
Harvey

I have a CS3 so not sure what you can do with a CS2 but since that is a fairly recent mfx loco the first thing I would try is resetting it.

Harold
Thanks for pointing out those findings/suggestions. I have to research further as this loc seems very complicated, likely due to the small size and compact design.

Regards
Harvey

I would not dare to open that loco up without first trying every other possible solution. Including looking to see if the cv settings can impact the lights. I have the same loco and will put it on my programming track to look at the cv's.My problem is I have a CS3 and am not sure how the CS2 handles loco edit and even if "Set Up" is an available option. The problem might not even be in the loco as the decoder is in the tender.
That loco has an unusual feature - unusual in that it is uncommon in most locos. the f1 function sends power through the coupling to activate lighting in the consist. Not sure how that will show up in the cv's.

Using the mapping function of the CS3 you have the following capabilities for the loco front lights and rear lights separately. On or off and when on either going forward, in reverse, or both. So it is quite possible that somehow the front lights were turned off.

You can try that but I am not sure if that completely deletes the loco data from the CS. If it does not work I will walk you through the procedure on a CS3 and you can look to see if it is also available with a CS2. First you should have a programming track. And place the loco on the track. Then find the "Edit loco" tab and click it. Then find the 37981 and click on it. That brings you to a screen with three tabs. Click on the "Set Up" tab and that brings you to a screen with a box in the lower left that says "Loco Reset". You click on that and just follow the instructions. I belong to a club ETE-ENE which has some members in Connecticut and N.Y.. I will look up Glen Oaks and see if you are near any of them who has a CS3. I am only familiar with the CS2 as a slave unit when we operate our club layout.

Hi Harvey
Recent Märklin MFX locos have 2 tools:
- one is deletion of the loco in the CS2. It re-initialize partly the loco and forces a new registration
- the other one is to access the loco by the CS2, then select the wrench signal to do some editing


Then you get a screen like this


There are 2 keys circled:
- the one in red is to re-initialize the loco to factory setting NOTE: the sounds are NOT changed even on a mSD3 decoder This will force a new MFX registration on your CS2
- the one circled in pink is used to update the decoder firmware. I suggest you do this only when you have serious problems

On recent Märklin locos the mapping is a very powerful tool and controls
- physical outputs characteristics: steady, blinking, pulsating, amplitude / brightness, telex, Mars light, etc
- sound fonctions: individual volume
- logic fonctions
- conditions on ANY fonction: forwards, reverse, moving, stopped

Here, for instance the individual volume adjustment on sound fonctions


and here the mapping of fonctions (assignment of fonction keys to physical fonctions, sound fonctions, SUSI fonctions (motorised pantographs, motorized coal level and much more.


These are poor examples of what MAPPING is but also how garbling with it (e.g.: the new CS3 updates 2.5.1 and 2.5.2 ) can change the physical and soun d fonctions

Having both a CS2 and CS3 I work only on the CS3 (the CS2 programming track output is dead) but I know first hand that the recent changes on Mapping is reflected on both the CS2 and the CS3

Note: all above screen are copies from my CS2 v4.3.0 (11)
Cheers
Jean

Do the rear lights work when the loco goes into reverse?

And did you do a reset with the CS2 or merely delete and reregister the loco. The problem is I don't know whether the reset accesses the original factory settings of the loco without the CS being connected to the internet or if there is someplace that the original CVs are stored. And I have no idea what the actual CV is for the front lights to work nor how to change them without a CS3.

According to Rick Sinclair, a Marklin USA employee. a Marklin mfx loco does not need to be on the programming track and the factory reset is stored in the decoder so no outside connection is necessary. He would be a good source for repairs if that is your decision