The MGA With An Attitude
LIGHTING SWITCH FAILS and Low Quality -- FT-088
Moss Motors part number 140-500, replacement for factory part 3H3089

Lighting Switch 140-500 -- 3H3089
I try not to harp on quality issues as long as a replacement part is at least functional. But this one finally failed I believe as a result of low quality issues ultimately making it dysfunctional and hazardous. I installed this one in 2007, and it failed in 2017. Life expectancy is not the issue, but along the way it more than once failed to connect leaving no lights, it would regularly have headlights on when in the parking lights only position (depending on how you jiggled the knob), will shear the wires when tightening the connector screws, and finally shorted to ground burning the power supply wire. Immediately below are pictures of the failed parts after the short to ground.

The power input terminal was touching the steel keying plate when the switch was pushed fully in to the OFF position. Must be the brass contacts are a bit too long. Or maybe the plastic barrel insulator broke to allow the power terminal to touch the steel shaft. The new switch is same model as the old one. First operation had the parking lights either on or off depending on a jiggle of the knob. At least it is not shorting to ground, but it can still cut the connector wires in the harness. If it does that, then the input power wire could short to ground against something on the dash panel. Going to have to keep an eye on this one for a while.

Moss Motors has been notified again. In spite of ten years of notices and bulletin board complaints about the quality of this part, it appears that Moss had done nothing to improve it.

See more information on additional quality and non-originality issues
in the Electrical section article E-117

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