My partner has just bought a 2011 Ford KA studio. 

 

I noticed that one of the side brake lights and the 3rd brake light (strip) were not working. The side brake light just required a new bulb so fixing this issue was quite easy. 

 

The 3rd brake light seems a little more confusing. I took it out the 3rd brake unit noticed that there are 5 bulbs in it, all of which look like they are fine. If there is an issue with one of these bulbs would the other bulbs still work? I've ordered some new bulbs for this but I don't actually think that's the issue. I checked the connections on to the unit and there is no sign of rust or anything else that could be causing an issue.  

 

I took a look in the manual and checked all fuses that I thought could have anything to do with the brake lights and they are all fine. 

 

Having read a couple of other posts I believe there is a brake light switch near the peddles but I think if this had any issues it would affect all of the lights (don't know this for sure so please correct me if I'm wrong).

 

Anyone got any idea what could be causing the issue and how to go about fixing it? 

 

Thanks 

check voltage present at the connector with a voltmeter.

by the way, the middle brake light is not a legal requirement or needed to pass the MOT.

MOT rules say that they can fail it for not working unless it has been permanently disconnected. It goes on to say that if there is any doubt about whether or not it has been disconnected the benefit of doubt should be given and not fail.

I do agree it would be better if it worked as it is safer with that extra brake light.

could be break in wire between the rear hatch and body of car where wire flexes when boot opened/closed. 

are the light bulbs 12 volts? if so, they are connected in parallel and not in series, therefore one faulty bulb would not stop the others working.  

Hello Isette 

Thanks for the response, yes it had passed an MOT the week before I bought it so thought it must not be required for that. 

Good idea regarding the voltage meter, I've not got one but I will put a call out to see if anyone I know has one. 

Yes they are 12v bulbs, I thought they should still work if one goes as I've seen that in other cars but it's good to have that confirmed.

I had taken a quick look at the wires and from what I could see they looked ok but I will investigate this further. 

My daughter's 2011 Ka has the same issue.  My thanks for the advice given on this post as her MoT is due.  No voltage at the brake light detected, hoepfully they won't fail it.

On 1/24/2019 at 6:38 PM, isetta said:

the middle brake light is not a legal requirement or needed to pass the MOT.

Not quite true. There is no requirement to have the third brake light but if it is fitted then it has to work. If you remove the light or cover it with black tape then it can be ignored for the purpose of the MOT.

I’m pretty sure it doesn’t have to be covered. I think the mot rules say if it’s been permanently disconnected then it’s ok and if any doubt about whether it’s been permanently disconnected then give the owner the benefit of the doubt. I know that sounds stupid.  

From mot manual, just checked it:

Vehicles first used on or after 1 January 1971 must have 2 stop lamps, one on each side

Additional stop lamps, over and above the mandatory requirements, must be tested. However, if you are not sure if they are connected, you should give the benefit of the doubt.             

It is my understanding that "if it is fitted" then it has to work.

For example you are following cars in a line of traffic, you can see the centre brake light of the car that is two in front of you. That car brakes but you can't see the other brake lights and so don't react to the potential of the traffic stopping.

If we go with the idea of fitting lights and not having them work it will be very confusing, what about fitting extra indicators but not wiring them ?

I know it’s totally illogical but I didn’t write the mot manual. 

@seanohareuk or anyone - did you find the reason for the issue? Was it a broken wire, and if, where was it broken?