PCT Limited; home of PCT Automotive and PCT Metalmex

Electrics Kits available for all cars and light commercial vehicles
Designed and manufactured in Sheffield
Tested independently at MIRA to EC/95/54
Multiplexed bulb failure, digital controlled lighting, mixed voltage lighting systems, low voltage side light systems
The UK's leading towing electrics manufacturer

ZK3000A & ZK3020A Towing Interface Relay Kits
Questions and Answers

Why have towing electrics changed so much over the last few years?
Vehicle manufacturers are constantly striving to improve the performance of their vehicles and the safety, control and comfort that the driver and passengers experience when travelling in their car. In the last few years the introduction of computer technology and digital control of the vehicle systems, to enhance the driver's control of the vehicle and provide the passengers with in car entertainment and comfort has been dramatic. Since the spring of 2000, vehicle designers have been introducing digital control to the driver activation of vehicle road lights. These new auto-electrical/electronic systems require protection from faults in trailer or caravan electrical systems, this has required the introduction of a new method of wiring the towing electrics.

What are the problems with installing towing electrics? Two problems inherent with connecting relay coils, filament bulbs, current switching contacts and caravan or trailer road light circuits to a towing vehicles digitally controlled road light circuits are, first, potential voltage spikes (noise interference) introduced onto the digital control wires, and second, the towing vehicles electronic digital control circuits may not be designed to carry high currents caused by faults that may develop in the caravan or trailer road light circuits.

What is the solution?
The solution is simple, PCT Automotive have developed a 7 Channel Car to Caravan/Trailer Towing Interface Relay (ZR1328A), which when installed isolates the trailer or caravan road light circuits from the vehicle road light circuits.

What benefits do I get by fitting a Towing Interface Relay?
The ZR1328A, 7 Channel Car to Caravan/Trailer Towing Interface Relay is designed to act as a buffer to prevent voltage spikes being introduced into the towing vehicles digitally controlled road light circuits. It also eliminates the possibility of a fault within the towed caravan or trailer road light electrical circuits from damaging the towing vehicle's digitally controlled road light circuits. The Towing Interface Relay also includes a built in audible device which buzzes when the vehicle's directional indicators operate, alerting the driver that the towed unit's indicators are working correctly (only when coupled to a towed unit), this function is a statutory requirement under the UK road regulations.

How do the ZK3000A and ZK3020A kits offer a solution?
The ZK3000A kits contain a ZR1328A, Towing Interface Relay, and all components and instructions necessary to install 12N towing electrics (suitable for use with trailer) to any* car or light commercial vehicle, including vehicles which have multiplexed bulb failure, digital controlled lighting, mixed voltage lighting systems or low voltage side light systems.

The ZK3020A kits contain a ZR1328A Towing Interface Relay, a ZR1220 Volton Combi Relay, and all components and instructions necessary to install 12N/12S towing electrics (suitable for use with caravan or trailer) to any* car or light commercial vehicle, including vehicles which have multiplexed bulb failure, digital controlled lighting, mixed voltage lighting systems or low voltage side light systems.

* Suitable for use on 12V negative earth vehicles only. Not suitable for earth switched vehicles, e.g. Jaguar S Type.

What benefits do I get by fitting a Volton Combi Relay?
Modern caravans contain a refrigerator and an on board battery, the refrigerator can be cooled and the battery can be charged during the journey to the destination, thereby saving time at destination in arrival set up. The ZK3020A Towing Relay Interface Kit contains a Volton Combi (self switching combination relay). The Volton Combi Relay has been designed to switch a positive 12 volt supply from the towing vehicle's battery/alternator power source to the towed unit's supplementary power system (caravan refrigerator/battery), without draining the battery of the towing vehicle. The Volton Combi Relay will only switch power to the towed unit's supplementary power system when the towing vehicle's battery/alternator has power output capacity in excess of that required to power the vehicle's own electrical systems.

Can I switch my vehicle Fog Lights off whilst leaving my caravan Fog Lights on?
The vehicle fog light off and caravan fog light on function is provided by the addition of the 'Fog Off' latching relay, an extra electronic unit to the ZR1328A, 7 Channel Towing Interface Relay. The vehicle fog light off facility does not require the cutting of vehicle fog light wires, and does not affect the integrity of the Multiplex CAN bus digital vehicles road light systems. Add ‘-FO’ after the kit number to include the 'Fog Off' relay.

Do the ZK3000A and ZK3020A comply with all relevant UK and European laws?
Yes. All products manufactured by PCT Automotive that require Type Approval Certification are certified and carry a label accordingly. Only Type Approved electrical and electronic systems should be installed in vehicles which carry a whole vehicle type approval.

When should I fit a ZK3000A or ZK3020A?
Whenever there is a requirement for a 12N or 12N/12S electrics supply connecting to a vehicle. For example, if a customer would like to tow a trailer, caravan, or connect a lighting board to their vehicle.

Where are the relays in the ZK3000A and ZK3020A installed in the vehicle?
The Towing Interface and Volton Combi Relays are installed in the rear of the towing vehicle, inside the boot compartment behind the trim. The ZK3000A and ZK3020A kits provide all the components and instructions necessary to install the Towing Interface Relay and the Volton Combi Relay.

My vehicle has mixed voltage lighting systems, does the ZR1328A Towing Interface Relay work with them?
Yes, the ZR1328A Towing Interface Relay has been developed specifically for mixed voltage road light systems.

What will happen if I fit a ZR1328A Towing Interface Relay to a vehicle which does not have digitally controlled lighting?
The ZR1328A Towing Interface Relay is designed to work with standard vehicle road lights as well as digitally controlled road lights.

Electrics Kit Selection

	A	B	C	D
12N 7 Pin (For Use With Trailer)	ZK3000A	ZK1226	ZK3001	ZK1227
12N/12S 7 Pin (For Use With Trailer/Caravan)	ZK3020A	ZK1375	ZK3021	ZK1389
13 Pin (For Use With Trailer/Caravan)	ZK3040		ZK3041

Type A Kits
'Complex' Electrics
Cars/Vans

Contain all components and instructions necessary to install towing electrics to cars or vans which have:-
• multiplexed bulb failure,
digital controlled lighting
• mixed voltage lighting systems
• low voltage side light systems

* Suitable for use on 12V negative earth vehicles only.
Not suitable for earth switched vehicles, e.g. Jaguar S Type.

Type B Kits
'Simple' Electrics
Cars/Vans

Contain all components and instructions necessary to install towing electrics to cars or vans which do not have:-
• multiplexed bulb failure,
digital controlled lighting
• mixed voltage lighting systems
• low voltage side light systems

* Suitable for use on 12V negative earth vehicles only.
Not suitable for earth switched vehicles.

Type C Kits
'Complex' Electrics
Chassis Cabs/Pickups

Contain all components and instructions necessary to install towing electrics to chassis cabs or pickups which have:-
• multiplexed bulb failure,
digital controlled lighting
• mixed voltage lighting systems
• low voltage side light systems

* Suitable for use on 12V negative earth vehicles only.
Not suitable for earth switched vehicles.

Type D Kits
'Simple' Electrics
Chassis Cabs/Pickups

Contain all components and instructions necessary to install towing electrics to chassis cabs or pickups which do not have:-
• multiplexed bulb failure,
digital controlled lighting
• mixed voltage lighting systems
• low voltage side light systems

* Suitable for use on 12V negative earth vehicles only.
Not suitable for earth switched vehicles.

Electrics Kit Contents	ZK 3000A	ZK 3020A	ZK 3040	ZK 1226	ZK 1375	ZK 3001	ZK 3021	ZK 3041	ZK 1227	ZK 1389
ZR1328A Type Approved Towing Interface Relay	•	•	•			•	•	•
ZR1220 Type Approved Volton Combi Relay		•	•		•		•	•		•
ZR1000A Type Approved Rear Audible Relay				•	•				•	•
12N Pre-Wired Socket (2m Cable, Plate)	•			•
12N/12S Pre-Wired Socket (2m Cable, T-Plate)		•			•
13 Pin Pre-Wired Socket (1.8m Cable)			•
12N Pre-Wired Socket (5m Cable, Plate)						•			•
12N/12S Pre-Wired Socket (5m Cable, T-Plate)							•			•
13 Pin Pre-Wired Socket (5m Cable)								•
Red Insulation Displacement Tap Connector	x7	x7	x7	x10	x11	x7	x7	x7	x10	x11
1m x 9/0.3mm White Wire	•	•	•			•	•	•
0.2m x 9/0.3mm White Wire		•	•				•	•
4m x 9/0.3mm White Wire				•	•				•	•
5m x 28/0.3mm Red Wire	•	•	•			•	•	•
5m x 44/0.3mm Green Wire		•	•		•		•	•		•
Grommet	•	x2	•	•	x2	•	x2	•	•	x2
Blade Fuse Holder	•	x2	x2		•	•	x2	x2		•
15 Amp Blade Fuse	•	x2	x2		•	•	x2	x2		•
Blue Fully Insulated Female Spade	x2	x4	x4		x2	x2	x4	x4		x2
Red 6.4mm Ring Earth Terminal	x2	x3	x2	x2	x3	x2	x3	x2	x2	x3
Blue 6.4mm Ring Earth Terminal		x2	x3		x2		x2	x3		x2
Connection Identification Warning Labels	x7	x7	x7			x7	x7	x7
Socket Fixing Machine Screw, Nut and Washer			x3					x3
Fitting & Maintenance Instructions and Written Product Guarantee	•	•	•	•	•	•	•	•	•	•