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MG TD TF 1500 - Wiring TD fog and driving lamps

I have a 52 TD MkII and recently purchased new fog and driving lamps from Moss. The wiring harness in the car provides for a fog lamp, but not a driving lamp.

Question 1:
For the fog lamp, there is one hot wire (red w/yellow stripe) coming off the harness but no ground wire. For the ground connection am I to just run a wire from the fixture to a convenient spot on the frame or is there another preferable way to ground the fixture?

Question 2:
For the driving lamp, I will need to run both hot and ground wires. I would also like to mount a toggle switch under the dash to control this lamp. Can you describe (or illustrate) a wiring method (or diagram) that would be suitable?

Question 3:
I've also heard that I should add a relay to the driving lamp circuit, i.e. use the switch to turn on a relay to turn on the lights, as the relay will hold the current a lot better than just a switch. This was suggested because driving lamps draw a lot of current. Any thoughts on this?

Thank you very much in advance for any information you can provide and Happy New Year!

Bryan Sieling
632 S. Highland Street
Arlington, VA 22204
Bryan

Brian,

A convenient point to connect the ground (black wires) to is one of the bolts that secure the bottom radiator bracket to the chassis.

For your driving lamp run a wire to your new toggle switch. There are two convenient places to connect the feed.
1) If you want the lamp to only work when the headlamps are on connect it to the H terminal of the lamp / ignition switch. This should have a blue wire.
2) If you want it to work when the headlamps are off connect to the A terminal on the lamp switch - this should have a brown with blue wire attached.

The original fog lamp switch is quite robust with contacts as large as many automotive relays so will be OK. Likewise get a good quality toggle switch. Impeortant to use correctly sized wires though. Would suggest min 28/0.30mm - takes 17.5 amps which is double for a single fog or spot lamp.

You could always do as I have done and arrange the wiring so the dash lamps come on with the side / tail lamps and use the redundant turn switch on the dash for the driving lamp. If you need a circuit diagram for this send me an e-m. Like wise if you do want to install a relay.


Have a good New Year

Jan T
Jan Targosz

Bryan
I'm not an expert, but this might help as I have just fitted a pair of Lucas SLR & SFT 576's to my TF.

1. I ran an earth wire from each lamp between the bottom corner of the radiator grille and the fender and fixed them to bolts underneath the front valance with ring terminals. The hot wires went thru the same gap.

2. I only used one relay which is switched by the RY hot wire and powered by a new wire from a battery isolation switch fixed under the bulkhead forward of the steering wheel. When the red key is removed the car is electrically dead = no lights. My aux lights only have 48W bulbs so I use both at the same time if the conditions are that bad. Either one can be disconnect if required by simply opening the hood and pulling one bullet connector out of the double joiner. You could take power directly from the live side of the starter switch.

3. If you do want separate switching I suggest you run and additional wire from the same source via an under dash toggle switch to the fog light. Forget a relay as the fog doesn't need to be all that bright.
Good luck
John
John James

Be aware that at 17.5 amps for the driving lights, you are already exceeding the output of the early generator and really pushing the envelope for the later generator (19 amps). This will cause a large draw on the battery and if you are driving a long distance at night it is possible that the battery will drawn down to where the voltage drops to a unusable level. If you don't drive long distances, there is not the problem.
Good luck - Dave

David DuBois

Bryan,
I have run 4 "pre-select" toggle switches off the "aux" switch on my TF. (Driving Lamp / Fog Lamp / Hunting Lamp / Map Light) Each with fuse & relay the "pre-selects" are mounted on a pannel under the dash. As David points out, running all 4 at same time would drain the batt. in short order, (not to mention that I would look like some kind of space ship comming down the roadway!)...but I do like the idea of being able to operate a varity of accesories off the stock switch this way.
Cheers,
David 55 TF1500 #7427
David Sheward

This thread was discussed between 31/12/2003 and 01/01/2004

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