Aygo centre brake light not working

[8bitnitwit]

So far I've tried changing the bulbs, checked the fuse, and replaced the whole unit with an LED version - none of them are lighting up.

The other brake lights on the rear of the car work fine. The wiring harness (what I can see of it) and connector that connects to the centre brake light also seems fine.

Any ideas where I should be looking next? It seems safe to say that no power is reaching the light connector when pressing the brake.

[flash22]

Get someone (or a bit of wood) to hold the brake and check for 12v and ground at the connector for the light, then test for 12v at the light and use a body ground

does the rear wiper work ?

[Vandals01]

(You will need a Multimeter.  Any cheap one under £10 will does the job.)

 

In the light assembly, you have 2 pins in the connector:

One pin is positive, that should give 12v when you step on the brake.

One pin is negative, that runs through the entire car's body. (So yeah, any metal that touches the car body which is not cover in plastic or paint will supply -12v).

 

Step one - verify you have positive 12v at the centre brake light when someone step on the brake.  Hook up the Multimeter, black lead goes to car body (the best ground at the tailgate is usually the tailgate latch assembly that is screwed onto the car body).  Red lead to the light's connector, poke each one until the multimeter reads 12v.

If you do not get readings that means the positive is bad.  Since left and right brake light works, chances are you got a broken wire.

If you do get a reading, next will be supply your own negative to the light and see if it lit up.  You can do it with the Multimeter.  Switch the multimeter to Current (Amp) AND MAKE SURE YOU USE THE 10AMP terminal or you will blow the fuse in the meter.  Black lead to the tailgate latch just like when you tested the positive 12v.  Red lead to the OTHER PIN at the light.  Obviously, with the light connected, you can't tap it the pin, but you can tap it to any metal that runs off the other pin.

 

[8bitnitwit]

Thanks guys. I'll test with a multimeter and get back to you!