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MG TD TF 1500 - Wiring Question

I am installing my new Moss wiring harness. The wiring diagram shows the coil terminals marked as "CB" and "SW". My coil terminals are marked as "+" and "-". How do these correlate?

The wiring diagram shows a black/white lead running from the coil CB terminal to the distributor terminal. The harness has no black/white lead, but does have a black lead and a white lead which branches to the coil terminals (see image). Can someone tell how how to make the coil and distributor terminal connections?

Corey Pedersen 1951 TD #7169

"CB" = contact breaker ( if your car is positive ground this is the +)
"SW" = switch ( this would be the white wire and attached to the - terminal for a positive ground system)

If you have converted the car to Neg. Grd. these would be the other way around.
C.R. Tyrell

Thx CR.

The car has been converted to negative ground. I should have mentioned that earlier.

OK, the white wire goes to + terminal. Still need to understand where the black wire goes, and what connection is made to the distributor.
Corey Pedersen 1951 TD #7169

The distributer has a seperate piece of wire, with the proper terminal/lugs on it, independent of the harness. It would go from the negative terminal on the coil to the stud on the distributer.
It would be good to wrap this wire around a pencil or rod first to form a neat coil. giving the wire some flexibility.

Jim B.
JA Benjamin


If your harness uses the original colour scheme then the black wire is a ground. probably from the E terminal of the voltage regulator. Check with an ohmeter if it does come from the E terminal, if so then fix it to a convenient bolt on the firewall.


J Scragg

Moss has confused people lately with this black wire. It has nothing to do with the coil and has the wrong connector on it.

You will need to change the connector to a 1/4" and put it on the bolt holding the coil to the firewall. Actually there is another bolt nearby that has nothing attached to that. Thats where it goes. But its also supposed to be on the other side of the firewall but at this point we are stuck with it on the top side.
Chris Couper

That clarifies everything. Thanks to all for the quick and complete response!
Corey Pedersen 1951 TD #7169


Just remember to us a low amp trickle battery charger with a internal overload in place of the battery when you get ready to test the new harness. This will save the harness and money if you have something a miss.

Ed Stanfield
ECS Stanfield

Corey, the white/black wire that connects the coil to the distributor may not be in the wiring harness. As mentioned above, the black wire coming out of the harness is a ground wire. Bud
Bud Krueger

Ed, good idea. I have a small 12V power source that will serve the same purpose and provide a little more amperage for testing purposes.

Testing will be interesting, since I have added quite a bit to the circuitry. I'ved added 13 fuses, a heater fan, provision for a fog light, turn signals, turn signal indicators, four-way flashers, a third brake light, headlight relays, a second fuel pump and a 12V power port. The fuse panels will facilitate testing by allowing me to isolate all of the circuits and test them individually. The image shows the under-dash hookups. It looks busy, but will be neater when I mount the fuse panels and other circuit components on an under-dash mounting panel.

Jim, I used your coiled-wire technique. Effective and professional looking.

Bud, the black/white wire is not included in the harness kit. Moss should provide a note to that effect (or include the wire).

Corey Pedersen 1951 TD #7169

This thread was discussed between 17/08/2013 and 18/08/2013

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