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MG TD TF 1500 - wiring loom installation help required

I have just got around to installing a new wiring loom to my 51 TD. Unfortunately the loom came without any diagram or instuction although I can use the diagram in the workshop manual. Can anyone suggest any literature that will help? The loom I have is intended for the models with separate control box and fuses but my car came with a 9 terminal box. Can they be interchanged.
Thanks John
j c rathbone

Make sure that you check every wire with a meter before you apply power. I ended up with 3 different wiring diagrams. Found out that all 3 were wrong. Burned up 4 wires before I could disconnect the battery. I ohmed every wire after replacing the damaged wires. Don't trust the diagrams!!!

Good Luck,


Use a battery charger for power when testing, never the battery. Battery has to many amps when testing and burnup can be a real problem with a high buck wiring harness.


The latsest TSO has a great coloured, 2-page diagram for the TD with separate control box and fuses. The diagram is 11 X 17 and is one of the best I've ever seen. Even the individual lines are colour-coded, and it is clear and concise.

I'll see if I am allowed to copy it (copyright and intellectual property rights, you know) and maybe send you a scanned copy.

Stand by.

Gord Clark
Rockburm, Qué.

Gordon A. Clark

Gordon - Here in the US copyright laws say that it is permissable to copy information out of a publication if it is for your own use or for research purposes. I though I remembered some time ago you wanted to research the difference between the TD and TF wiring and I understand that John Rathbone in the UK has volunteered to help you - am I correct or... Cheers - Dave

John - With or without the TSO print, if you have the shop manual for the TF, you can determine the color code fo the wires and from that check both ends of each wire to see if it goes to the proper location. get some wiring lables from the local electrical outlet near you and as you verify the inds of the wires, put a lable on it and note on a sheet of paper where each tag goes. Then, as Tom suggested, once the wiring is complete, substitute a battery charger set to the lowest current available for the battery to see if thngs are going to work without a lot of bothersome smoke. The other alternative is a 5 to 10 amp fuse (you want a fuse that will blow at 5 - 10 amps) in series with the ground lead.
Good luck - Dave
David DuBois

Hi John ---- It's too bad your new harness is not correct for the original voltage regulator the car has. The functions are the same and with great care you should be able to hook your harness up to a 9 post regulator. Any chance you could swap your harness for one made to go with a 9 post?

I did two cars and found that the colors in the harness matched those listed in the workshop manual quite well. I labled each wire with a piece of masking tape on each end and when I fired it up, everything worked just as it should.

The idea of using a battery charger, expressed in earlier posts in this thread, is a good one. I wonder though how that works when you test the headlights. For everything else it should be dandy.
Good Luck -- shoot me an email if I can be of further help!

R. K. (Bob) Jeffers

Thanks for all the comments. The battery charger for testing is a good idea and I have decided to get a 5 terminal regulator (this is correct for the chassis/frame number) The colour chart would be helpful if it can be copied.
John Rathbone
j c rathbone

Hi John --- OK, if you go with a 5 post Regulator you will also need a fuse block. Must be a DPO put in a 9 post cause he could get it cheap (or quickly).

I think you made the correct decision to go with the 5 post, since you say that the cars serial number tends to indicate that it should have a 5 post.

Does your new harness also include wires for directional signals? Don't know how it is felt in the UK about them, but they are d**n near manditory here to keep from getting hit in the behind. With the petrol tank where it is, that could be a major disastor. In fact, I put an extra light bar on top of the petrol tank with magnetic mounts so that I have an extra stop light, an extra tail light and extra turn signal lights. Makes me feel much safer even in broad daylight. With the magnetic mounts I can remove it easily for shows etc.

Good Luck, and Holler if I can be of any further help.

R. K. (Bob) Jeffers

Hey Bob,
How about sending me a pic off list of what your light bar looks like? Sounds like good idea.
Greg & Grimm
G.J. Cenzer

Speaking of magnetic mounts...just a note on something handy... I keep 6 - 1" rare earth magnets on hand and a sheet of plastic rolled up in the back. When i happen to be parked outside and it looks like rain, i just cover the cockpit (with or without tonneau) with the plastic sheet and pop the magnets on the cowl and rear fenders... Saves getting everthing wet and smelly and is really quick to set up and remove. (ok, it looks like hell...)
gordon lawson - TD 27667

Dave DuBois,

Wasn't me! But I intend to find out if its OK to scan the excellent diagram in tne TSO, and make it available to needy others. The TSO is published in North Carolina, but the intellectual property content is assembled and edited in Canada so it may not be straight forward.

Gord Clark
Rockburn, Qué.
Gordon A. Clark

Along with G.J. Cenzer's reply, I would be interested in the design of the light bar you mentioned that could provide additional stop,directional and tail lighting to the 51 TD I'm restoring.
Tom Burke
T. Burke

This thread was discussed between 21/07/2005 and 24/07/2005

MG TD TF 1500 index

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