Busta4 Make Adaptor

Busta 4.2 - Connector Fitting Instructions to make an 'in-line adaptor'


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The Busta 4.2 is designed for use by all 12 volt negative earth towing vehicles (known to LAB Electronics at the time of writing) that have been built to European lighting regulations and are towing trailers which have only one tail/licence plate lighting circuit and do not require monitoring of the trailer’s turn signal LEDs.  It will provide the vehicle with trailer recognition and when required, stop the trailer’s park, brake and turn signal LEDs from blinking.

Busta 4.2 is not to be fitted to the towing vehicle, as that vehicle will always (falsely) recognise that a trailer is connected.

Busta 4.2 can get very HOT when in operation.  Do not restrict ventilation to the Busta 4.2 nor place it on/near plastic or any other heat sensitive materials.

Carefully read the instructions all the way through.  If you feel that you are unable to perform any of the operations, please seek the help of someone who can.  Refer to the ‘You will need’ list near the end and gather all the tools and materials to complete the installation before you proceed.

Busta 4.2 has a 600mm long (2ft) 7-core cable rated at 10 amps per wire.  It is supplied without trailer connectors because trailer connectors vary greatly around the world.  Obtain locally the type of trailer connectors that you need to make Busta 4.2 it into an in-line adaptor.  Locally obtained connectors may have different uses and different wire colours indicated for their individual terminals. When there is a conflict with the Busta 4.2 wiring, follow the suggestions for the use of the connector terminals, as it will make troubleshooting any faults, at a later time, much easier.  Copy the plug and socket wiring page at the end.  Identify the uses and colours of the wires on your trailer and write them down in the space provided on the plug and socket wiring page. 

Busta 4.2 is internally connected to the trailer’s LEDs using the Australian trailer wiring colour scheme - yellow (left turn), green (right turn), red (brake light), brown (park and license plate light) and white (earth) wires.  Each of the LED driver circuits is capable of driving up to 4 amps of LED current.  Do not connect any lamps (light bulbs) to the LED driver circuits on the trailer.  The blue and black wires go straight through from one end to the other and can be used for any purpose.  If you do not require these wires, you may cut them back and leave them disconnected.  The labels on Busta 4.2 are marked VEHICLE on one end and TRAILER on the other end.  The plug that fits into the socket on your vehicle goes on the cable from the VEHICLE end and the socket that fits the plug on your trailer goes on the cable from the TRAILER end.  Following the fitting instructions and the “use” information for your chosen connectors fit them to the Busta 4.2 cable ends.  At the connection points you will need to remove from both cable ends the minimum amount of outer sheath that is required to make all of the wiring connections. 

Testing the operation of the trailer LEDs

With the vehicle ignition and lights switched off, connect the trailer to the vehicle.  Switch the ignition on and check that any trailer LEDs that were previously blinking have stopped and the trailer telltale does now operate with the turn and hazard signals.  Start the engine, switch the park lights on and operate the foot brake to check the operation of those LEDs and check that there are no lamp failure warnings.  Refer to last page if there are.  

Sealing the cable ends after testing


All Busta 4.2 cable ends are sealed internally during manufacture to prevent liquid and dust entry.  As an extra precaution, the ends of the 7-core cable inside the connectors should also be sealed.  After you have tested the operation, please apply a small amount of silicone sealant or liquid electrical tape to the open end of the outer sheath, around and in between the individual wires using a small screwdriver (or similar tool) to push the sealant into the crevices if required.  Before the connector covers are fitted re-inspect the sealing at the cable ends and ensure that they are still properly sealed.  If they require re-sealing add more sealant. 

Operational note

Always connect and disconnect the trailer with the vehicle’s ignition and lights switched off.  Connecting or disconnecting the trailer with the vehicle’s ignition and/or lights switched on can cause malfunctions to be indicated, or unintended operation by some of the vehicle’s computer systems.   


You will need a Busta 4.2 and:

A plug to fit the trailer socket on your vehicle
A socket to fit the trailer plug on your trailer’s cable 
Silicone sealant or liquid electrical tape
You will also need various hand tools – Side cutters, wire stripper, screwdrivers, needle nosed pliers.

Warning - Busta 4.2 can get very HOT when in operation

Without a wiring modification a vehicle that does not have an electric brake controller fitted cannot be used to tow a trailer with electric brakes.  Because the vehicle has two park light, circuits when the park lights are turned on one of the circuits will activate the trailer brakes.  When the park lights are turned off the trailer's brake solenoids are de-energised, this puts a very, very large pulse of energy from the collapsing of the solenoids magnetic fields (back EMF) into both of the park lighting circuits.  This will almost certainly damage the Busta 4.2 and may possibly damage the lighting controller in the vehicle.  Modification – open the trailer plug and disconnect the trailer electric brake wire (Blue for Australia).  This will stop the brake solenoids from being activated/de-activated.  Reconnect the trailer electric brake wire when finished towing.

Trailers with load resistors fitted – Do not connect a Busta 4.2 to a trailer with load resistors fitted as the load resistors and LED arrays may require more current than the Busta 4.2 can comfortably supply (max 4 amps).  Please disconnect any load resistors on a trailer before connecting a Busta 4.2.

Horse floats – It has been found that some manufacturers have connected non-LED lights, inside the horse floats, to the park light circuit of their trailers.  Please check which type of lights are fitted and to which circuit they are connected before connecting a Busta 4.2.  These lights use too much power for the Busta 4.2 to supply (max 4 amps) and overloading will void the warrantee.  You will either have to replace them with LED lights or modify the wiring of the trailer and vehicle to supply a different power source for the horse float's internal lighting.

Trailer Brake LEDs pulsing
A new generation of 'high end', electric brake controllers for trailers are on the market.  When fitted to a vehicle the controller emits a stream of pulses to the trailers electric brake solenoids to ensure that they are connected to the controller and when there is a problem will warn the driver.  It has been found that some trailer manufacturers are installing a diode between the wires going to the trailers brake solenoids and the brake LEDs.  This will cause the brake LEDs to flash with the pulses from those controllers.  Busta 4.2 cannot stop this type of pulsing.  To test this – with the ignition on - open the plug on the end of the trailer cable and temporarily disconnect the trailer electric brake wire (blue in Australia).  If the trailers brake LEDs cease blinking then you will have to contact the trailer manufacturer to obtain the location of the diode in the trailer wiring harness so that it can be removed. 


Busta 4.2 Mk4 is warranted against defects in parts and manufacture for two years from purchase.  All care is taken during manufacture to seal each unit to the IP-68 rating however due to the severe operating conditions, in which it can be used. It is not warranted against internal or external corrosion or any damage caused by liquid or dust ingress once it has been put into operation.  It is strongly recommended that you regularly check the assembly for possible liquid and dust entry points (nicks, cuts, abrasions, etc.) and seal any openings with silicone sealant to prevent the ingress of any liquid or dust as entry could eventually work its way along the inside of the cable and corrode the wires and electronics.  Please return Busta 4.2 to LAB Electronics for damage assessment and repair, as there are no user serviceable parts inside.

Busta 4.2 Mk4 is designed for 12 volt direct current negative earth vehicles and trailers.  Each LED driver circuit can drive up to a maximum of 5 amps of current.

Do not connect any lamps (light bulbs) to the LED driver circuits on the trailer.

Busta 4.2 does not conform to E/ECE/324 – E/ECE/TRANS/505 regulations as it has only one park light circuit and does not monitor the trailer’s turn signal LEDs and is therefore unable to inform the driver if a fault is present by turning off the trailer telltale in the instrument cluster.  The onus is always on the driver to check that all of the vehicle and trailer lighting is functioning correctly.  

A trailer lamp failure warning appears in the vehicle when the park and stop lights are used.

As the lamp check modules in most vehicles do not have the functionality to check a trailers park and stop LED circuits the internal load resistors inside both the Busta 4.2 and Euro have been fitted but are not connected.  These load resistors develop quite a bit of heat and waste power, and as in most cases, they are not required, they have been left unconnected. 

If you do receive a trailer lamp failure warning, you will have to carefully undo the cable gland tail and rubber seal, remove the two screws on the trailer end of the unit and access the three wires inside of the unit at that end.  If you feel that you cannot perform these operations, please locate someone that can.

On the trailer end of the unit undo the cable gland tail – Grip the 19mm (3/4in) body nut of the cable gland with a THIN spanner, so that it will not rotate on the end plate and break the silicone sealant seal.  Loosen the tail with another 19mm (3/4in) spanner.  Once loosened undo the tail completely by hand and slide it along the cable away from the body.

Remove the black silicone sealant from the two screw holes in the trailer end plate with a hobby knife or similar tool.  Remove the two screws from the end plate and check that the O-ring seals under the screw heads are still there.  To access the rubber seal carefully move the end plate a short distance along the cable then move the end plate back against the case of the unit, grasp the seal and slide it along the cable as far as you can away from the body.  Move the end plate along the cable as far as you can away from the body.  Check that the sealing gasket on the end plate is not damaged.

Fish out the three insulated wires with pre-stripped ends from inside the unit.  The White wire has an end cap fitted.  The Red and Black wires have plastic sleeves fitted over the bare wires at their ends.

The White wire is the earth wire.

The Black wire is for the park circuit load resistor(s) – one resistor for the Mk4 and two resistors for the Euro.

The Red wire is for the stop circuit load resistors – two resistors in all units.

If you have a lamp failure warning only on the trailers park circuit then connect the Black wire to the White wire.

If you have a lamp failure warning only on the trailers stop circuit then connect the Red wire to the White wire.

If you have a lamp failure warning on both the trailers park circuit and the stop circuit then connect all three wires together.

Un-screw the end cap from the White wire and remove the sleeve from the Red and/or Black wires, straighten the bared wire ends and twist the ends of the required wires together and screw the end cap from the White wire over them to terminate the required two or three wires you have twisted together.  If only two wires have been terminated leave the sleeve over the remaining unused wire, if all three wires have been terminated the plastic sleeves are no longer required, Please dispose thoughtfully.

Place a small amount of neutral cure silicone sealant around the surface of the end plate gasket and refit the end plate using the original screws.  (check that the O-rings under the screw heads are still fitted.)  Place a small amount of neutral cure silicone sealant (black) to cover the screw heads as they were originally sealed.  Slide the rubber seal along the cable and into the cable gland.  Hand tighten the tail onto the cable gland.  Use two 19mm (3/4in) spanners, one THIN one on the nut, to tighten the tail onto the gland without breaking the silicone sealant seal between the cable gland nut and end plate.