ISO 1185:2003

Overview

ISO 1185:2003 specifies the physical and functional requirements for the 7‑pole 24 N connector used for the electrical connection between towing and towed vehicles with a 24 V nominal supply voltage. The standard defines dimensions, contact allocation, mechanical and environmental tests, and marking requirements to ensure interchangeability and safe operation of trailer/tow vehicle electrical interfaces.

Key topics and technical requirements

• Connector type and layout
  • Defines a 7‑pole plug and socket: six smaller spring tubes/pins (Contacts 2–7) plus one larger tube/pin (Contact 1).
  • Dimensional drawings (plug and socket) determine form, pitch circle and locking features to ensure physical compatibility.
• Contact allocation and wire colours
  • Contact functions and recommended core insulation colours:
    • 1 - Common return (White)
    • 2 - Left‑hand rear position & registration plate illumination (Black)
    • 3 - Left‑hand direction indicator (Yellow)
    • 4 - Stop lights (Red)
    • 5 - Right‑hand direction indicator (Green)
    • 6 - Right‑hand rear position & registration plate illumination (Brown)
    • 7 - Braking control for trailers (Blue)
  • Note: rear registration plate lamps shall not share a common connection to both contacts 2 and 6.
• Electrical and mechanical terminals
  • Rear terminals accept nominal conductor cross‑sections: Contact 1 = 2.5 mm²; Contacts 2–7 = 1.5 mm².
  • Contact identification must be permanently marked inside the socket cover and on terminal faces (character size ≥ 2 mm, smaller allowed where space is limited).
• Identification and protection
  • 24 N connectors must be distinguished from 24 S by darker permanent colouring (preferably black).
  • A storage/protection provision for a disconnected plug is required to prevent ingress of water and damage.
• Tests and performance
  • Test sequences reference ISO 4091 with specific requirements: mismating prohibition (no contact between Contact 1 and Contacts 2–7), locking/cable retention force 500 ±5 N, connection/disconnection force 150 ±50 N, modified temperature/humidity cycling (−25 °C to 75 °C), salt spray and endurance (1 000 cycles) as specified.

Applications and users

• Intended for heavy commercial vehicles, trailers, semi‑trailers, drawbar trailers and towing vehicles requiring standardized 24 V electrical interconnection.
• Primary users:
  • Vehicle manufacturers and OEMs
  • Trailer and connector component suppliers
  • Fleet operators, maintenance engineers and vehicle inspectors
  • Test laboratories validating connector compliance
• Practical benefits: ensures plug/socket interchangeability, safer trailer lighting/braking connections, simplified maintenance and global compatibility.

Related standards

• ISO 3731 - 7‑pole connector type 24 S (supplementary)
• ISO 12098 - 15‑pole connector (alternative for >7 functions)
• ISO 4091 - Definitions, tests and requirements for towing/towed connectors
• ISO 4009 - Location of electrical/pneumatic connections
• ISO 4141 - Multi‑core connecting cables

Keywords: ISO 1185, 7‑pole connector, 24 N, 24 V, towing and towed vehicles, contact allocation, trailer connector, connector dimensions, electrical connector standard.