A bit of a mystery to me (I'm new to this). I have a power cable in my car like this: enter image description here

The back of my new Pioneer stereo has a connector like this: enter image description here

Basically it doesn't fit (the plug does not have the 2 notches but just a flat notch on the top)!

Do I need to cut off the plug from the ISO adaptor lead (which came in pioneer radio box) and solder onto the power cable in my car (or is there an easier way)? It looks like this (which of course fits in the back of the stereo):

enter image description here

2 Answers 2


You need to buy an adapter. Don't hack up your car's wiring harness to install an aftermarket head unit. The connector which came with the head unit should have loose wires. The adapter which you'll get will be specific to your vehicle and attach directly to the plug which is part of the car. It will then have free wires which will match the color codes on the plug for the Pioneer head unit. Attache those two up, then plug it into the head unit. Plug in the antenna, then fire it up.

  • Thanks for the advise - the new head unit just came with the ISO harness wiring loom (third picture), no loose wires. Do you know the best place to buy these adaptors? Incidentally, the car I'm fitting it to is an '89 Toyota MR2 Mk1(!)
    – Jeb
    Aug 5, 2017 at 22:59
  • Most any electronics store should have it for you. Here in the States I'd either buy it online or go to something like BestBuy or maybe even Walmart. Not sure where you'd be able to go in the UK. If the head unit was actually "new", it should have the part which plugs into the back of the unit. If it's not there, take it back to where you bought it and tell them to get you one. Aftermarket companies provide this automatically with the new head unit. Aug 5, 2017 at 23:01
  • 2
    @Jeb Either the bay of fleas or a car audio shop or Halfrauds will have them, other DIY places have them but they may only carry a limited range.
    – Solar Mike
    Aug 6, 2017 at 7:58
  • I ended up buying the same brand head unit as the one I replaced, for the socket and plug to be compatible. In hindsight, I should have inspected the plug/socket before purchasing the radio! All works fine now. Thanks!
    – Jeb
    Aug 8, 2017 at 14:42
  • Incidentally, I have a JVC/Kenwood plug there - hence got another Kenwood :)
    – Jeb
    Aug 8, 2017 at 14:44

As long as the original Toyota plugs were still there it would have been easy to resolve - Toyota to ISO adaptor lead. They are about £6.00 The wiring looks a mess with all the intermittent "tap on" connectors. Would get rid of these asap - they cause nothing but trouble.

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