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MG TD TF 1500 - Lighting Issues

OK, so it's always something - right? Had the car out in the street tonight for the first time. I wanted to check all the lights for proper operation and effectiveness prior to my inspection due next month. I noted:

1. While my turn signals work fine with the side or main lights OFF, when the side or headlamps are on, the "bright" fillament of the signal bulbs isn't all that bright. They do function, but their intensity is weak. I cleaned the contacts, but no change. Without the side or headlamps on, they are fully functional and much brighter. Since I was playing with timing, etc. prior to this check, could the battery be run down a bit causing this? Comments?

2. What is the meaining of "Main Beam" on the speedometer. I always assumed the light came on with the high beams to alert you as such, as it is with all other vehicles. Mine comes on with the low beams and goes out when high beams are selected on the floor dip switch. Only thing I can think of is that the main and dip wires are reversed on the double "snap connectors" shown on the wiring diagram. If this is possible, where are the double snap connectors located. If not possible, what else should I look for.

Thanks for any help on the above.

Larry
L Karpman

Larry,

It sounds like the wires on your hi/lo beam switch (behind the horn button) are reversed. If the problem were further away than that, the hi beam light on the speedo would be correct. Since it isn't, all pojnts to the hi/lo beam switch.

Cheers,
Lew Palmer
Lew Palmer

Lew. Is that switch behind the horn button there even though I have a floor mounted dip switch?

Larry
L Karpman

I should have mentioned that it is only the front side light signals that blink very dimly when when the lights are on. The rears are fine.

Larry
L Karpman

Well DUH! I usually, 99% of the time, check the archives first. This time I did it second. I apologize for wasted space. I saw Dave DuBois' answer to a similar question on 1157 bulbs in the archives, with the caution to ensure they were installed right side up, or the wrong filaments would light and drown out the the signals. DUH - again!

In any case that solves that issue. Still need to troubleshoot my high/low beam indicator illuminating for low beam.

Larry
L Karpman

Larry Check to see if when the dash Main Beam indicator is on, the blue/yellow wire has 12 volts on it. If so the car is wired correctly but the headlamp sockets are not.
Cheers,
Bob
R. K. (Bob) Jeffers

Thanks Bob. As usual my faded harness colors causes grief. I won't be able to check the blue/yellow wire as I can't ID it. Any other way to check this out?

Thanks

Larry
L Karpman

Larry How about up under the dash? Colors may still be identifiable there.
Cheers,
Bob
R. K. (Bob) Jeffers

Larry, I just took a peek at the (foot) dipper switch of the53. As far as I can tell, the wires are still original. Looking at the wiring diagram (N.23 of the Workshop Manual) you can see that there are two 4-way connectors by the dipper switch. One is for the low beams (dip filament) and has three #2 wires in it (blue with red). The other is for the main filament (high beams) and has four #4 wires in it (blue with white). Thne fourth wire is the one that goes up to the high beam indicator. I found these two connectors under tape very close to the main harness, near where it comes through the firewall by the steering column.
Bud Krueger

Alas Bob, they are not. Just as faded there as everywhere else :-( I will replace the harness at some point, but it won't be soon enough.

Larry
L Karpman

Okay, we can resolve this for Larry by a bit of reverse engineering. Does anyone happen to know the correct wiring scheme for the headlamp socket? There are three terminals. Which is common? high beam? low beam?
Bud Krueger

larrys, tom do you have an OHM meter? if so, just grab your wiring diagram and trace them out. regar
tm peterson

An ohm meter (multimeter set to read resistance) will trace out the wires for you, but first you have to disconnect one end of each wire you are trying to trace so that you don't get any sneak paths that will lead you further down the garden path. Once you disconnect one end of a wire and use the meter to determine where the other end is, mark both ends with some tape, labled with the color code from the wiring diagram from the shop manual. Cheers - Dave
David DuBois

Yes I have a meter, so thanks. Also, Bud you are correct in that looking at the wiring diagram, it shows the main beam light is connected to one side (Blue/white) on the floor mounted dip switch connector. Both main beams connect there. The other side (blue/red) has a dual connector for the 2 low beams (dip). If the main beam speedometer light is connected to the dip side by mistake, would this not create the issue I have? Worth checking I think, but....

In looking at what I believe to be the snap connectors for the headlamps, located about 10" or so from the floor mounted dip switch Right about at the steering column path), they are dried out messes and I would need to replace them as they would no doubt crumble trying to swap wires. Also, no way to determine wire color there either. That said, as the wiring is probably original, that might shoot down my speculation about the main beam indicator light being hooked to the wrong connector (dip), as it would have to have been switched at the factory. But then again, a PO in the last 50 odd years could have done it.

That leaves the possibility of the connectors at the headlamps being incorrectly wired. I do not think they are the original connectors, as they are set up for modern sealed beams. So, a possibility there.

Thanks to all for your input, and it looks like I'm fixing to get rid of this old harness sooner than later.

Larry
L Karpman

I believe I may have solved the issue. I pulled the headlamps (again, the PO spliced in modern sealed beam bulb connectors). Just for grins, I swapped the inputs to the original Lucas connectors (which like the rest of the car were crumbling), an voila, the main beam indicator illuminates when high beam is selected. When it quits raining on Saturday, I'll take it out at night an ensure all is correct :-)

Thanks to all again.

Larry
L Karpman

Good job, Larry. Classic trouble shooting question --"what could the PO have done?"
Bud Krueger

This thread was discussed between 29/03/2007 and 30/03/2007

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