Boot wiring - I've messed it up on my MG TF 135

Hello All,

I have just joined and I guess like most my first request is for help, I am slightly gutted in having owned my TF less than 24 hours and made it worse. To be fair I could cry, I started the day with working brake lights and now have nothing...

I knew yesterday the high level boot brake light was not working and thanks to this website I knew it was likely to be the boot wiring loom having snapped with use, on investigation this morning this had been previously modded, therefore I surmised the wiring was at fault under the layers of insulation tape. I undid all the tape to find nothing seemingly amiss, however in my excitement at fixing my new car, I forgot to undo the battery (I hadn't realised this yet) and put the whole thing back together as I had found it, only to then discover that nothing I now worked, including all the brake lights. The Hazards and the tail lights work, but the brake lights, boot light and the boot opening warning was on.

After a brief panic I decided to it properly and having disconnected the battery, brought some wire strippers and terminal blocks and wire them up methodically. In my mind the wires that leave the boot should match the colours in the car, however whoever had done the wiring previously had placed a plain black wire from the car into the red/black wire from the boot (but his solution worked). So I wired up the three black wires into the same terminal (I believe they are all earth wires?) and matched up all the others, when this failed I wired it up as the previous owner had and still nothing.



I know it's not the best photo but it just shows the general arrangement I was going for, I was going to tidy it all up when it worked, which it didn't. The boot open warning light has now gone, but the brake lights are still completely off as is the boot light. I checked fuse 15 and all seemed okay and the horn works.

So effectively I have undone someone else's job and now b*ggered it right up.

Is there a plug in the engine bay that I could of accidentally pulled out? Any clues would be greatly appreciated as I am gutted I've knackered it up.

Thank you

Oly

Hi,
You need to check first fuse 26, its a 15A fuse thats in the fusebox under the steering wheel. This feeds the brake light circuit.
There are also two larger fuses backing this up under the bonnet in the fuse link box that is behind the battery. Link 5 is a 40A fuse link and then link 6 is a 60A link. Both of these links feed fuse 26 which is the brake light fuse.
The only other things in the circuit is a switch contact on the ignition switch and the switch on the brake pedal and the negative earth returns which go to local header points.
Turn you ignition on and if you can, test for voltage on the green and yellow wire that goes to the brake switch if all the fuses mentioned beforehand are ok.
If you have voltage there, then operate the switch to see if it switches and test the green and purple wire that comes from the switch to the tail lamps and high level brake light. If you have voltage on that wire, test it back at the lamps while someone presses the pedal for you.
You can make a simple volt tester by using a 12v lamp and a couple of bits of wire if you do not have a tester or multimeter.

Hope this helps, Sundance

Hi Oly and :welcome: to the forum from John in Yorkshire.
Well Sundance has given you some good pointers so all I can add is don't get yourself in a tizz . To be fair there aren't that many wires to get wrong . Just take your time and there are always wiring diagrams that may help you on this forum .

Hi and welcome to the forum Oly

For some strange reason each circuit in the boot lid has a separate earth. They can be combined.

There are wiring diagrams in downloads under the community tab at the top of the page.

James

I made some tutorials on this topics if they might help you:

1. https://forums.mg-rover.org/mgf-mgtf-12/mg-f-tf-boot-hinge-lid-wiring-loom-inspection-guide-866231/

2. https://forums.mg-rover.org/mgf-mgtf-12/mg-f-tf-fuse-relay-listing-487819/

Anyhow, if you are missing corresponding wire colours from the car (as it seems to me on your picture), the you might want to strip isolating tape around wires deeper in the engine compartment as somwhere there previous owner must joined these new wires to old ones, and there you can find colour wire match.

Yes, agree with Roverlike here,
Remove the metal grill and follow the wires down into the engine bay. It would not surprise me, looking at the pictures that you will find other joins in these wires, so remove any tape and strip them back, and you will find the corresponding coloured wires.
David

Thank you all, a lot for the quick replies. I did suspect I had done something to the wiring much deeper inside, or like you say someone else has, I'll try and grab some better photos when I get another few hours to work on it, just frustrating when you don't have much time, and I wanted to swan about it on the weekend.

I did send my Dad out today who reckons the fuses are all okay in her, so it must be something in the engine bay further.

I am lucky to have a local decent garage who are specialists in Renaults and they seem quite good at bringing back old lagunas from the dead, so I thought if anyone knew anything about wiring and electrics they are the boys, so they are going to take a look at it along with fitting a new exhaust and temp sensor.

Hopefully though (touches wood) that should bring it to a good level, I brought it blind on eBay....

Oly