There are two ways to do this:

#1. Most common is as you suggest replace the wheels with Isolated pickup type contacts on the wheels and a small constant lighting circuit in each car to avoid the flicker and dimming and brightening effects of direct to track contacts with voltage increases and decreases as the train speeds up and slows down

#2. add a Coin battery system with 1.5v bulbs or LED`s but with this system can get expensive with the battery replacement & or the price of rechargeable batteries and the recharger. You can make a recharging system that will recharge as the train rolls and this can be very expensive too as each car using lights will require the circuit.

From your question it look`s like you want to light just 1 Coach and I`m looking for the constant lighting circuit for you to build and yes you will need the electrical pick up wheel sets or trucks with pickups and metal wheels and axles in order to power your lighting system.

Unless someone beats me to adding the constant lighting circuit I`ll be back soon.

Dan

but one of our sponsors, Rapido Trains, makes lighting circuits that run off watch batteries, called "Easy Peasy" lighting.  Check them out on their website www.rapidotrains.com/light_ho.html 

I'm not sure of the exact application you have in mind, but here are some simple constant lighting circuits for DC and DCC for consideration.

Car Lighting

Hi ,Thank you for your reply. Sorry I did not make it clear,I want to put head lights and maker lights in the cab end with a decoder

Are you talking about a caboose or a passenger car with an operator's cab in the end for push pull commuter operations?  The old MDC-Roundhouse steam locomotive kits used metal wheel sets in plastic frames for the tenders and used a brass or bronze wiper for tender pick up.  Those wipers used to be available for a low price from MDC, but since Horizon bought the company, I don't know how much of the old stuff is still available.  Any plastic truck can be made "live" electrically by using a wheel set with metal axles and one wheel on each axle on the same side insulated.  I also saw a thread where the poster used Kaddee centering springs from a #5 coupler bent up to make wheel wipers and picked up power from the spring through the mounting screw, but I dont remember if it was on this forum or another one that I visit.

Hi, Yes a passenger car with an operator's cab in the end for push pull commuter operations.

Thank you for the advice.

  Peter

I think most Athearn passenger cars are design to be lighted and that the trucks are designed so that all you need is a lighting kit added to the car to use track power to light the interior.  If that is the case, you could use a lighting kit to power your cab lighting.