First off, whom ever gifted you the car set should have ordered the A/C version. then you'd have no issues.
Can it be returned and exchanged? It would save you a lot of aggrivation.
You'll also have better wheel grounding because no wheels will be insulated from one rail. However, converting is done all the time. The pick-up shoe can be ordered, it's part # should be listed on the instrction sheet, or on the A/C version parts list on Roco's site.
Once you have the shoe, just remove the car body with the decoder, and follow the wire from the ground, and the + plus power rail side wire to the decoder. That wire gets unsoldered from the wheel pick-up and soldered to the shoe.
Note; The Locomotive does not enrgize the car lighting. This car set has a decoder of it's own, so you can set it to DCC on your CS3, but it won't auto recognize like MFX. Default address is 03. To change the address, use the programming track. Roco Zimo function decoders are not yet MFX.

this is from the Roco website. At the bottom of the page there is the list of spare parts. The coupler, of which there is no picture, costs € 17+

https://www.roco.cc/ren/...t-%22railjet%22-obb.html

I don't know how easy it would be to remove one of the Roco couplers and NEM pocket and install a current conducting coupler by Marklin both on the engine and on the coach. If this is doable then you can use this set. I haven't seen if they ever made an AC set at all though. If there is, look at the catalogue, then a swap may be easier. I've stopped finding a way to 'hack' things, life is too short 😊

I wouldn't be surprised to see something in the New Items which is only a week or so away.

To cut the story short , yes you can add lights to your Roco Railjet cars, you have to figure out which electrical coupling you need for your loco, a male or female Roco electrical coupling, this is your first step, the second step is to find out which pin goes where, headlight, markerlight, interior lights, common wire,
I would like to see the underside of the driving cab and see if there is a lid you can open up and insert a decoder ?, this will depend on how you would proceed with wiring regarding your loco,
if there is no room for a decoder connect the male coupler to your female Roco electrical coupler, use a 14-18 volt DC power supply and find out which pin does what., when you've established this you than can figure out wow to get the wires from the electrical coupling into the loco, we also need a picture of the loco's circuit board, which is important and see if there are Aux functions left over to use for the interior lights., this would be the first thing you have to investigate before you order Roco electrical couplings, so all in all, provide a picture of the underside of the Roco cabcar, also of the circuit board of your loco., also let me know how many pins the Roco electrical coupling has, are you handy with fiddly work and soldering ?, you don't have to worry about the axles beeing DC and it doesn't look like your bogies are in the position to take any slider.

until than I can suggest further options


John

The Roco Railjet sets were designed to be powered from the locomotive, meaning that there were current conducting couplers from one end of the train to the other.
Using these coaches with a Maerklin rather than the Roco locomotive will mean that you will either have to adapt the locomotive or the lead coach in order to couple them together.
The Roco model was designed so that in AC operation, the train would get power from the leading end.
If you can replace the coupling at the coach end connecting to the locomotive, you can adapt the Roco coach set so that the coaches draw their power from the pilot coach. This may require installing a function decoder in the pilot coach.
When running a Railjet, there are also versions which are for use in Italy, others for Switzerland and the markings are different on those coaches. The HO Models are interchangeable, but the prototypes normally don't mix.

My recommendation would be to keep searching for a complete set of Roco models. The Railjets are also made by Jaegerndorfer and a basic hobby model comes from Piko

You can also use your Railjet (Taurus) with normal red/white/beige OBB coaches from ACME, Roco or LSM (1/87) or Maerklin (1/93)

One suggestion might be to contact Reynaulds. They list some Railjet material as on consignment and may be able to offer some solutions and complementary items to solve your issue

Regards

Mike C

I have Roco Railjet AC, the first release around 2010. Coach lighting is always on, and takes power from pilot coach. Pilot coach headlights and high beam are controlled by a function decoder.
Current conducting couplers have four pins but only two wires (red and black) are connected

regards