Auto Electrical Service
Trailer Wiring
7-pin and 13-pin socket installations and tow bar electrics.
Towing is serious business in South Africa. Whether you're pulling a horse float, boat trailer, caravan, or utility trailer, the electrical connection between your vehicle and trailer must be correct — both for legal compliance and safety. Mobile Auto Elec installs and repairs trailer wiring across Johannesburg.
Trailer Wiring Services
- 7-pin (round) and 13-pin (caravan) socket installation
- Bypass relay installation to protect modern vehicle electronics
- Breakaway systems for trailers with brakes
- Auxiliary battery charging relay for caravans
- Fault diagnosis on existing trailer wiring
- Trailer board / lighting bar wiring
Why a Bypass Relay Matters
Modern vehicles with electronic body control modules cannot have trailer sockets wired directly into the lighting circuit — the module cannot handle the additional current and will fault. A bypass relay (also called a dedicated module or towbar wiring kit) is required. We fit the correct solution for your specific vehicle.
Frequently Asked Questions
A 7-pin socket handles the basic trailer lighting functions (indicators, brake lights, tail lights, reverse). A 13-pin socket (common on caravans) additionally provides 12V power for the caravan's internal 12V system and charges the leisure battery while towing.
Almost certainly yes if your vehicle has electronic body control modules (most vehicles made after 2005). Wiring directly into the harness without a relay will cause module faults and may void your vehicle warranty. Themba fits the correct relay kit for your specific vehicle.
This is typically caused by a bulb with the wrong resistance (common with LED trailer lighting), a faulty bypass relay, or a failing indicator flasher unit. It's a common fault and usually straightforward to resolve.