ISO Wiring Harness Adapters UK

Choosing the right ISO wiring harness in 2026

An ISO wiring harness is the simplest, safest way to fit an aftermarket car stereo in 2026. Instead of cutting the factory loom, you plug the harness into the original vehicle connector and join the matching colour-coded leads to your new head unit. This guide from Bass Junkies explains how to pick the correct lead for your car and what to wire up where.

What is an ISO harness and why use one

ISO 10487 is the European wiring standard used by most car makers since the 1990s. An ISO harness converts the vehicle plug into a standard set of speaker, power and accessory wires, ready for any aftermarket stereo. The big win is that the factory loom stays intact, which protects warranty wiring, keeps any future trade-in tidy and lets you reverse the install when the car is sold or scrapped.

Honda all-models harness

The Connects2 CT20HD02 covers most Honda Civic, Jazz, Accord and CR-V platforms with a factory ISO-compatible connector. It plugs straight in, with separate ignition, constant 12V, ground, illumination, speaker and amp-remote leads brought out the other side. No cutting, no splicing, no risk to the factory loom.

Older Jeep 14-pin harness

The Connects2 CT20JP01 is the right lead for older Jeep Grand Cherokee, Wrangler and Cherokee platforms running the legacy 14-pin block. It saves cutting the original loom and avoids the very common ignition-feed mistake on those vehicles, where the constant and switched 12V are reversed compared to a UK car.

Brand quality at a glance

• Connects2. UK-designed harness adapters trusted by trade installers since the early 2000s.
• Autoleads. Long-running OEM-grade harness brand for European and Asian car makers.
• PAC and Axxess. Premium integration brands for cars that need CAN bus or amplified-system harnesses.

Pin-out and colour code

Every ISO harness in this collection uses the standard colour scheme. Knowing the basics avoids miswiring on install day and saves an hour with a multimeter.

• Yellow. Constant 12V for memory and station presets.
• Red. Switched ignition 12V, on when the key is turned.
• Black. Chassis ground, run to a clean unpainted bolt point.
• Blue with white stripe. Amp remote turn-on output.
• White, grey, green and purple pairs. Front and rear speaker outputs.

Compatibility and fitting

An ISO harness is rarely the only part you need. For a true factory-look install we usually pair it with the matching fascia and stalk kit, ordered together to save a second courier charge.

• Fascia adapter. Vehicle-specific trim ring that hides the DIN cage in the dashboard.
• ISO harness. The lead from this collection, matched to your vehicle.
• Steering-wheel control adapter. Keeps the factory wheel buttons live on the new stereo.
• Aerial adapter. ISO-to-DIN antenna converter for clean FM, AM and DAB reception.

Solder, crimp or quick-splice

Soldering and heat-shrinking gives the longest-lasting joint and is the method our workshop uses every day. Insulated crimp connectors are a fine alternative for confident DIY installs, especially in a dry dashboard environment. Quick-splice scotchlocks are the option to avoid, since they cut through wire strands and corrode quickly in vehicle door looms and footwells where moisture eventually reaches. A small soldering iron, a pack of heat-shrink and a roll of self-amalgamating tape lasts most DIY fitters a decade.

Why buy from Bass Junkies

Bass Junkies has supplied UK installers and DIY enthusiasts since 1995, working out of our Wolverhampton workshop with proper trade stock rather than drop-ship listings. Ring us on 01902 863 005 to confirm the right harness for your vehicle before you order. Same working day dispatch on stock items, fitting advice on every line, trade pricing for return customers and a real workshop on the end of the phone if the install hits a snag.