Product details
Maypole 12v 7-way bypass relay with audible buzzer and 7-pin 12n pre-wired towbar socket
Here’s a practical, no-nonsense towing electrics pack that does the job without faffing about. The Maypole MP3877B 12v 7-way bypass relay sits inline with your vehicle’s lighting circuits and drives the lights on a trailer or caravan, while the included pre-wired 7-pin 12N towbar socket gives you a neat, ready-to-fit connection. It keeps the load off the vehicle’s lamps and gives clear audible feedback if something’s not right — handy reassurance when you’re towing.
Key features and benefits
- The relay connects directly to the vehicle lighting circuits so the trailer lights are powered safely without extra load on the car’s bulbs or wiring — helps avoid blown bulbs or dimming lights when towing.
- Built-in audible buzzer monitors the indicator circuits and chirps to warn of faults; the buzzer automatically mutes when the hazard warning lights are on — useful if you’re hitching up on a busy road.
- Designed to cope with dual-voltage tail/brake and tail/fog arrangements, so it’ll work with many common rear light setups.
- Includes a 7-pin 12N pre-wired towbar socket with a 1.5m, 7-core cable, plus a flexible gasket and mounting plate for a tidy install.
- Can be powered from either the vehicle battery or the fuse box and provides an ancillary flasher/indicator monitor output for a panel lamp or an extra buzzer.
Compatibility, what to check and typical use
This relay is compatible with most vehicles using conventional filament bulbs and with many LED lamp combinations. It’s suitable for cars that use multiplexed (shared-signal) wiring for position/brake and position/fog lights — provided those signals appear as physical wires at the rear light clusters. For proper indicator monitoring you’ll need separate indicator signal wires to each rear cluster.
Important: it won’t work with vehicles that use fully digital or networked lighting systems (for example some CANbus-only setups) where there are no direct rear signal wires. If you’re not sure about your car’s wiring, get it checked by a qualified auto electrician before buying — saves time and stress.
Technical details and handy info
- Model: MP3877B
- Voltage: 12v
- Relay type: 7-way bypass relay with internal audible buzzer
- Socket: 7-pin 12N pre-wired towbar socket with 1.5m, 7-core cable
- Extras: flexible gasket and mounting plate included
- Power: can be supplied from vehicle battery or fuse box
- Made in the UK
If you want reliable trailer lighting without loading up the vehicle’s circuits and like the peace of mind of audible indicator monitoring, this Maypole combo is a sensible, straightforward choice. It’s great for DIY installs or a technician’s quick-fit job — just check your vehicle’s wiring first, as it won’t magically make a digital-only system play ball. In short: less faff, clearer warnings and a tidy towbar socket ready to go.