Lighting update for the Bachmann Class 66/0  Heavy Freight Diesel Locomotive

EWS Class 66/0 at Penrith June 2009



The early Class 66 variants used by EWS were fitted with light housings that include forward marker lights in the outboard locations. (These are in addition to a dedicated rear light and headlight in each light cluster.) The lack of space behind these lights limits the options for LED reproductions of the original marker lights in the 00 scale Bachmann model. This supplement to the Class 66/9 web page shows how tiny 0603 surface mount LEDs can be used for this purpose.

Note that the smaller pictures can be enlarged by clicking on the image.

EWS Class 66/0 locomotive at Ely Station in June 2009


Scope of the project:

This page covers the additional work required to fit original style marker lights and cab lighting to early Class 66 locomotives used by EWS as modelled in 00 scale by Bachmann. Circuit concepts are similar to those explained in the Class 66/9 page, although some minor differences to the circuit diagram are shown below.

In the Bachmann model, although the early light housing is correctly modelled, the marker lights are painted rectangles with no operational capability. The headlight operation on the original model is correct only for daylight running.

On the real loco, daylight running uses all three forward marker lights plus the right hand headlight. Night running uses all three forward marker lights plus the left hand headlight. Both rear lights are used during day and night running if the loco is moving "light engine" i.e. without a train in tow. When towing a train, no rear lights are shown by the locomotive, but instead, a single rear facing, flashing red rear light is fitted to the rear wagon of the train. (To see a way to produce a realistic flashing rear warning light for DCC freight trains: click here).

The original Bachmann light housings with "painted on" marker lights

Circuit Diagram for the new lighting system, as fitted to Bachmann's early Class 66 number 66068: 

Note that the newer Bachmann Class 66/0 number 66152 in DB Schenker red livery, uses more recent circuit boards (derived from the later Class 66/9 models). The circuit diagram for this model is therefore different to the one shown below. (e.g. rear lights intensity is fine but top markers are too bright).

Click here for a DB Schenker livery 66152 conversion circuit diagram.

Note: The 4k7 resistor used in series with one of the end 2 rear lights is different as I broke the original SMD LED and replaced it with a different type.

The Bachmann decoder provides directional white and yellow wire outputs that are used to power the marker and rear lights. The TCS FL4 decoder is used to power the headlights and to select day or night running lights. PNP transistor switches under the control of the Bachmann white and yellow wires, enable the head lights at the correct end of the loco. A third transistor switch, under the control of the FL4 decoder, switches the rear lights on or off. An additional hazard warning mode of headlight operation is also available using the FL4 decoder pink wire.  The original rear lights were too bright, so extra series resistance has been added. The resistors in series with each LED control the current flowing through that LED. This determines the intensity of the light generated by the LED. The above values were established by experiment, for the LED types employed. Some adjustment may be required if different LED types are used.


Surface Mount 0603 size LEDs

These devices were sourced from DCC Supplies (also available from Bromsgrove).  0.2mm diameter enamelled copper wire was carefully soldered to the rear pads of the LED. (Click here for advice on soldering the wires to the chip LEDs)


Three of the 0603 LEDs with wires soldered in place, next to a mm/cm ruler


Fitting the LEDs to the Bachmann model:

1. The new left hand headlights

LED Mounting pads and a wire solder pad are already provided for the missing left hand headlights on the lighting PCB. (See the Class 66/9 web page for access to these PCBs). Just solder the new LEDs to the mounting pads and attach the additional wire to the rear of the PCB. (The older Bachmann models use large 1206 size LEDs although on newer Class 66/0 models such as the red DB Schenker 66152, smaller 0603 size LEDs are used.)

2. The new 0603 marker light LEDs

Rectangular apertures need to be made for each marker light. The cavity is required to be somewhat deeper than the 0603 LED, to accommodate the wires on the rear of the chip. Finally, a hole is required from the upper part of the aperture, for the wires to penetrate the top of the light housing close to the edge of the moulding (where it will be hidden by the overhang of the upper body shell moulding, immediately above the light housings. (Note: clearance slots will need to be filed in the upper body shell to correspond with the wire positions on the chassis.)


Apertures cut

LEDs fitted and super-glued in place

(Incorrect lifting lugs also removed)


Holding the new LEDs in place and making the electrical connections:

Drops of super glue hold the LEDs in place and filler plus paint is used to make good any surface damage. The two adjacent marker LEDs are connected in series and then connected via a series 100k resistor between the appropriate Bachmann common positive supply wire and the white control wire for end 1, then the yellow control wire for end 2.

Correcting a buffer beam error by Bachmann:

While the chassis unit was clamped in the vice, the opportunity was taken to remove the two right hand side lifting lugs from the buffer beam. Although these are fitted to the later Class 66/9 locos, they are absent on all EWS / DB Schenker Class 66/0 locomotives (the subject of this model).

Prototype with marker lights wired and activated

Programming the CVs:

Using the DCC controller (mine is a Bachmann Dynamis) the CV values were programmed into the TCS FL4 decoder (with the Bachmann decoder completely isolated from the controller).

FL4 CV Purpose

FL4 CV Number





Green wire function  (rule 17 dim f&r)



Purple wire function (rule 17 dim f&r)



Brown wire function (full on f&r)



Pink wire function (x2 strobe f&r)






Green wire control button (2)



Purple wire control button (1)



Brown wire control button (9)



Brown wire control button (9)



Pink wire control button (6)






Dimming active (headlights)



Dim amount (headlights)



Dim all the time button (5)






The "rule 17" dimming option provided in the TCS decoders has been used, so that when the train is stationary, the headlights and marker lights are dimmed. As soon as the train is made to move, these lights come up to their normal intensity.


Testing the Lights:

Button 0 should activate the marker lights in the forward end of the loco and with Button 9 also pressed, should activate the rear lights in the rear end. (Rear lights are switched off by leaving button 9 off.

Button 2 activates the right hand (daylight running) headlight in the forward end of the loco, or alternatively, button 1 activates the left (night running) headlight.

With buttons 1 and 2 off, Button 6 activates all 4 headlights in double strobe hazard warning mode for yard shunting operations.


Day running lights are OK (buttons 0,2,9)


Rear lights work OK (buttons 0,2,9)


Night running lights are OK (0,1,9) 


(Button 6 controlled headlamp strobing is also O.K.)                Conclusion: All is working well!


The finished Class 66/0

Postscript:   DB-Schenker Class 66/0 66152

66152 day running

66152 night running

Final comment: I've just discovered that yellow water colour paint can be used successfully to add a hint of yellow to the lower marker lights

Supplier website links:


Hattons of Liverpool    The Class 66-0 units above were purchased from this very reliable mail order company.
Trains 4 U (Peterborough)    A good (almost local) source of Bachmann and Dapol product. They also stock TCS decoders and offer good technical advice.
Bromsgrove Models    Excellent source of DCC decoders and specialist LED devices for this type of project
DCC Supplies    DCC specialist supplier based in Worcestershire. Good prices on Tower LEDs and TCS decoders
TCS (Train Control Systems)    A U.S. company. My preferred DCC decoder family with good programming data and advice on their website.
Maplins    My usual source for resistors and transistors, with two convenient local shops.


Photos of the real class 66 were taken at Penrith & Ely in June 2009.   The photos of the model were taken on the kitchen worktop using a tripod.    


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