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ZIMO function mapping MX660

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I’m quite big on my DCC sound but most of the time it’s steam locos and therefore less inclined to include lights. (I’m talking N gauge here) 


Anyway, I’ve started to fit some diesels now in my fleet and I’ve got myself up to my Graham Farish 108 DMU. 

I really want to have carriage lighting so I’ve made my myself two bars of LEDS to go inside. I seem to have run out of functions however. 

I’m using an MX660 drop in board and have completed the install apart from the light bars. 

functions 1 And 2 are the directional lights 

functions 3 & 4 are the directional cab lights 


I’d like to be able to switch the light bars on and off and could probably lose the cab lights or have them on the same bus. The output from the AUX is 3v so maybe I would need two  separate functions for each carriage to provide the right power for up to 5 LEDS on each carriage 



I have no idea how to remap the functions and struggling to get it to work. If anyone can offer any advice that would be most helpful - I’d love to get the inside lights going!



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Documentation on the MX660 is a bit limited at present, unless you read German.   SBS in the US has some stuff, making reference to the constant current function outputs (rather than "track voltage less a bit", which is more common in other decoders).




To operate standard "light bars" from commercial sources, which are likely to be a number of LEDs (so need more than 5mA of the constant current) and be configured to work from something nearer to 12v,  then I think a transistor acting as a switch will be needed, or an optocoupler acting as a switch. 



There are 6 outputs on the MX660, but with the constant current nature, they're not quite the same as normal outputs.  Plus there are two more underneath at logic levels if the appropriate CV's are set. 



Once the wiring, current and voltages are sorted, the programming for Zimo is well documented in Zimo manuals, supported in various pieces of software including JMRI, or a programming tool which YouChoos offers.  

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Thank you guys.


here is what the lighting looks like in one carriage so far .... I have used tin foil and white paper in the roof and the leds are soldered onto two brass rods facing upwards. With the reflection that the paper brings I think I could use the same aux for the other carriage and not have any brightness issues. This is currently using 5 leds....


the obvious issue is that I need to make it not direction dependent !




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Just wanted to ask if anyone knows how to make the directional cab light function non directional? 

I can’t find the answer and keep messing up the results and having to reset my decoder. I have finished my installation  and it so annoying not being able to see it working !



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1 hour ago, RedgateModels said:

depends which wire you have used, if it's the white wire write a value of 1 to cvs 33 and 34. If you used the yellow wire write 2 to cv33 and 34


thank you for your reply!


all this seems to do in my case is turn off the front headlights on one end completely. 

here is the wiring I have used 




and here is the decoder layout 



Thanks in advance 


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15 minutes ago, Nigelcliffe said:

Or use one of numerous other methods to set up lighting behaviour for Zimo.   

Knowing which wire or function output pad was connected may help with specific advice.




where is a good place to have this information in front of me? The manual for zimo seem SO complicated it’s like a different language 

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Not being able to read decoder raises this question - what DCC system are you using for programming track ?   And what mode of programming ?  (It should be Direct Mode on the Programming Track output).     Until you can get a system which reliably reads the decoder you're unlikely to make a lot of progress. 


Next, diagram is very confusing as to what is wired where.   I believe you have "front cab" on F02 and "rear cab" on F04 ?    In which case, the default function map ought to put those onto FunctionKey#2 for F02 and FunctionKey#4 for F04 ?    Is that what you have ?  Or is there something different due to the sound project settings from the sound supplier ? 


If the function mapping has been changed by the sound supplier, then information about that mapping might help me and others understand what you have infront of you. 






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I have Z21 system. 

what’s strange is it is just this decoder behaving like this. I have the exact same decoder on another loco working and ready writing completely fine for all the same values. (Exactly the same lighting set up too) 


if I can learn how to make the cab lights non directional on this other loco and test it - I can test the same approach on the offending decoder so that’s good at least. 

one time I adjusted the acceleration values etc and the cab light functions started flickering together and it drove off at full speed with no throttle!!! It has a complete mind of its own. How does that happen? 


you are correct about F02 front and F04 rear. 

here are the values from youchoos






hope this helps 







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14 minutes ago, markw said:

Changing CV128 and CV130 to 0, will make both of the outputs wired to the cab lights non directional, controlled by function key 12.


oh wow thank you it worked ! 

the decoder only allows one programming move then it changes everything to 255 and says can’t read CV so unfortunately I can only have both carriages lit in one direction and forced to use the default decoder settings. 

do you think it is faulty? My other MX660 with the exact same setup and lighting does not do this. 



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