The most reliable method for the GCC-spec vehicles common in the UAE is to use a multimeter set to the resistance (Ω) setting. In our workshop's experience with models like the Toyota Land Cruiser and Nissan Patrol, the terminal that shows a measurable resistance reading (typically between 2-4 Ω) when one probe is touched to it and the other to the horn's metal body/chassis ground is the positive (+) terminal. The negative (-) terminal is usually connected directly to the vehicle's chassis ground. According to the RTA Dubai Vehicle Inspection Manual, ensuring correct polarity is part of the basic electrical system check for vehicle registration renewal, as reversed connections can affect relay operation. The MOI UAE's General Directorate of Traffic also highlights proper accessory installation to prevent electrical faults. For a typical sedan like a Toyota Camry, the cost of diagnosing and correcting a wrongly connected horn, including potential fuse replacement, can range from AED 50 to AED 150 at independent garages, based on 2024 service quotes from Dubai and Sharjah.
- Diagnostic Tool: Multimeter on resistance (Ω) mode.
- Typical Reading: 2-4 Ω between positive terminal and ground.
- Common Practice: Negative terminal is often chassis-grounded.
