Many thanks for your replies, yes, I have studied the EZ commands, however the controller that I use is a ZTC 505 and not a Bachmann one. 

I have recently bought a few Bachmann locomotives ready equipped for DCC operation.
The loco's in question all have "lights" (example item no. 60348 HO GP40 Alaska) Question is how do I get the lights to work ?
I use a ZTC 505 controler and although I have tried CV values 49 and 50  on the test track I cannot operate the lights.
Can anyone tell me the CV values that I should be using, or give me a step by step instruction.
I have no problem reprogramming the decoder (directional/ speed etc) but am sure that I must be missing a stage out or using a wrong value.

All help greatly appreciated.

Thanks Pacific Northern,  that is indeed the one. I'll put it on E-Bay and go for a ready DCC equipped one.

I have recently purchased a second? hand Bachmann locomotive.
Its the Daylight GS4 4-8-4 which was sold under the catalogue number 11301.
I have never attempted to place a DCC locomotive decoder into a Bachmann loco before. Has anyone had experience of converting this locomotive to DCC ? If so, can you give me a step by step guide. I haven't even attempted to remove the body yet, but it has been test run and responds beautifully.

For information, my controller is a ZTC 505 and I can use any "chip" with it.

TIA for any help