Check the fuse first: switch off the ignition, find it using the diagram on the fuse box lid, pull it and look at the link or test it with a tester. Replace it only with the same rating — the colour tells you which. If a new one blows straight away, look for a short instead of fitting a bigger fuse. If the fuse is fine but there is no power, inspect the connector: pins come out with a depinning tool after the secondary lock is released, without force.
The power socket, one headlight, the radio or a window stops working — and the first thought is an expensive repair. In reality two small things are most often to blame: a blown fuse or a poor contact in a connector. Both can be checked in half an hour without special equipment.
Part 1. The fuse
Where to look
Most cars have two fuse boxes: one inside (under the steering wheel, at the side of the dashboard or in the glovebox) and one under the bonnet. The lid or the owner’s manual has a diagram with numbers and circuits. There is often a plastic fuse puller inside the box.
How to check it
- Switch off the ignition and the device that isn’t working.
- Find the fuse on the diagram and pull it out straight with the puller, without wiggling.
- Hold it up to the light: a good fuse has an unbroken link; a blown one is broken or scorched.
- Or test it in place through the two metal test points on top: a probe or test lamp shows whether there is power on both sides.
Colours and ratings
Standard blade fuses about 19 mm wide use the same colours across all makers.
| Colour | Rating | Colour | Rating |
|---|---|---|---|
| grey | 2 A | blue | 15 A |
| violet | 3 A | yellow | 20 A |
| tan | 5 A | clear or white | 25 A |
| brown | 7.5 A | green | 30 A |
| red | 10 A | blue-green | 35 A |
Never fit a fuse with a higher rating than specified, let alone a wire bridge. A fuse protects the wire: a bigger one lets through current that can melt the wiring and set it on fire.
An experienced auto electrician on the Mini owners’ forum gives a simple rule: if a new fuse blows straight away, don’t fit a third — find out why. And don’t panic over a single blown fuse: fuses age, and a tired one can go without any fault.
based on The Mini ForumIf the fuse keeps blowing
The cause is a short or an overload. Most often a wire has chafed where it moves or vibrates: in the rubber boot between the body and the door, near the boot lid, under the seats. Another common cause is a faulty power socket or a cheap charger plugged into it. Unplug everything on that circuit and reconnect things one at a time.
Part 2. The connector contact
If the fuse is fine but power doesn’t reach the device, inspect the connectors along the way: green corroded contacts, a pin backed out of the housing, or a broken latch. A pin can be removed, cleaned or replaced without changing the whole connector.
How to remove a pin without breaking the plug
- Disconnect the negative battery terminal.
- Unplug the connector and see from which side the pin is held.
- Release the secondary lock. This is a coloured plastic insert (TPA) that stops pins backing out even if the main latch fails. Slide it out a few millimetres or remove it — gently, so its own tabs don’t snap.
- Insert the tool from the mating face — into the gap next to the contact where the locking tang sits, not into the pin opening itself.
- Push the wire slightly forward from behind to take the tension off the tang, hold the tool in and ease the wire out backwards.
- If it won’t come, don’t pull harder. Take the tool out, insert it again and check the secondary lock is released.
Before removing pins, photograph the connector from both sides: in a 20-way plug it is very easy to mix up which wire goes where. Push the pin back in until it clicks clearly, give the wire a light tug, then refit the secondary lock.
If the wire next to the pin is broken
Cut out the damaged section, join the wire with a butt connector or solder, and always insulate it with heat shrink — how to do it properly is covered in crimping and heat shrink.
FAQ
Can I fit a 15 A fuse instead of a 10 A?
No. The rating matches the wire in that circuit. A bigger fuse won’t blow while the wire is already overheating — and the wiring can catch fire.
Why did a fuse blow once and never again?
Fuses age, and a brief current spike or a faulty gadget in the power socket can blow one too. If the new one holds, you’re fine.
How do I find the secondary lock in a connector?
It is an insert of a different colour — often white, red or violet — on the mating face or the side of the housing. While it is in place, no pin will come out.
Can I remove a pin with a needle or hairpin?
Sometimes it works, but a needle bends the tangs and scratches the contact. A tool of the right shape presses only on the lock, so the pin and the housing stay intact.
Sources and workshop experience
- The Mini Forum — an auto electrician’s notes: why fuses blow, why never to upsize, and when to hunt for a short
- Lazada Auto Guides — removing terminals safely: secondary lock first, tool from the mating face, no force
Updated 30.09.2026 · PayPayPlast editorial team — we test the advice on our own repairs
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