hi all,

all my brake lights are not working they just stopped about 3 days ago.

i have changed a bulb, the fuse and even the brake switch. still nothing.

there is a little bit of rust on the bulb connection itself,but dont think that could be the problem as all 3 went same time. or could it.

could this be caused by anything else other than faulty wiring. as i do not have any diagrams and a lot of garages telling me they dont or cant fix the problem.

any help much appreciated.

 

oh and there is nothing else wrong with the car, so far.

According to Haynes, Fuse 45 (15A) feeds the stop light switch(GnWh), to a soldered joint(GnWh) for the three brake lights (GnRd,GnYe,GnBk), and to the ABS(GnBk).  Only other place it might go is to a trailer socket.  Two different earth points, so I think a meter might be needed !

Thanks for the reply.

Yes I changed fuse 45. It looks like I'll have to get it checked in a garage as my knowledge only goes so far.

have booked my mot for Monday afternoon. Poor timing to say the least.

I will have to ring around desperately tomorrow morning.

Thanks again

 

2 hours ago, glyn7000 said:

I'll have to get it checked in a garage

It's not a garage you really need. You need and Auto-Electrician and most garages don't have one. Do a search locally for Auto-Electrician and You should find a few that will be able to help.

I will have a look at the wiring diagram tomorrow and see if i can suggest any pointers.

Looking at my diagram, firstly is your reverse light working ?

If not check f30 15a, if that is ok then either you have a bad ignition switch or relay 41 is bad.

Basically +12v is fed from FE / FF 60a

FF SUPPLIES RELAY CONTACT which then goes to reverse and brake light switches which when pressed

supplies +12v to brake bulbs or reverse bulb.

FE supplies ignition switch which in turn goes to relay coil, when this is activated the relay contacts close

and completes the FF supply.

Really important you check the reverse light first !

then check f30 15a

then check for 12v on relay 41 pin 1 when ignition is on, if no +12v then ignition switch at fault.

I can only assume all earth points are present.

My bet is ignition switch is at fault

 

A get out of jail (temp bodge) to get you through mot, is to connect +12v to fuse 45 & 48 green/blue cable behind fuse panel or remove relay 41 and put a jumper link between pins 3 & 5.

But only temporary !

If that doesn't work but reverse light does then you have a brake light earth issue.

 

 

My reverse light is working. 

I will check f30 tomorrow and go through what you said. Hopefully it can be resolved.

If not then I may try the quick temp bodge. 

 

If it is faulty earth do you know where the earth is or could it be one of several ?

 

If that gets me through mot then I will find auto electrician as mentioned above 

16 minutes ago, glyn7000 said:

If it is faulty earth do you know where the earth is or could it be one of several ?

It is not likely to be an earth fault if both brake lights are out and also you have a working reverse light as each light cluster is independently earthed (ie. left side and right side have their own earth point).

Ah ok.

So if I check fuse f30 and that's good.

I could replace relay 41. ??

Then if nothing, surely changing the ignition switch would solve it. Looks like R3 on a diagram I have

Might be getting somewhere here and hopefully get it sorted for MOT.

Thanks all for helping by the way.

 

Well in that case if reverse light is working then F30 will be ok.

you have an open circuit from F45 onwards on the green /white cable which paul kp mentioned in the first reply.

And as Unofix says above the rear brake lights are independantly earthed so almost impossible for an earth fault.

Good thing is, you now know ignition switch and relay are not at fault, so probably just a Fuse (45) cable or connector at fault.

BTW, the bodge i mentioned will make no difference

You do really need a voltmeter with continuity function - its literally a few minutes to sort, carpets and plastics will be your worst enemy.

9 minutes ago, glyn7000 said:

Ah ok.

So if I check fuse f30 and that's good.

I could replace relay 41. ??

Then if nothing, surely changing the ignition switch would solve it. Looks like R3 on a diagram I have

Might be getting somewhere here and hopefully get it sorted for MOT.

Thanks all for helping by the way.

 

If ignition switch was at fault, then the reverse light would not work.

There is an awful lot of stuff fed from Relay41 aka k79 Ignition Switch Relay.....wipers, fogs, blower, ABS, Windows... If they all work, I would suggest that the relay is OK.....

This is an appended diagram to show what I have done to my car so has a few additions....

12 hours ago, Paulkp said:

There is an awful lot of stuff fed from Relay41 aka k79 Ignition Switch Relay.....wipers, fogs, blower, ABS, Windows... If they all work, I would suggest that the relay is OK.....

This is an appended diagram to show what I have done to my car so has a few additions....

Would you agree that it must be o/c on the green/white from brake switch to rear brake light term.

I cant see any other reason ?

 

Yes, Certainly where I would look first, between Brake Switch to Soldered joint (wherever that is hidden!).  As you said earlier, a meter is required, as even with a good fuse, we do not know if the 12V is getting to the brake switch, let alone to the lamps.

(Other very remote possibility is that there is a short to chassis somewhere on that line, and the fuse continues to blow, but OP has not stated if the fuse had ever blown.)

Yes, has to be metered, i don't think Glyn will have one, even one of them bulbed screwdrivers, with a fly lead and croc would be sufficient...