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MG MGA - Dim low beam headlights

Problem: The headlight low beams are very dim while high beams appear to be normal brightness. I have checked all grounding contacts, cleaned them and reconnected. The headlight low beams are normal brightness if connected to a hot wire from the battery.

The voltage regulator may be the problem, but a trial with a new MGB voltage meter gave the same results, dim low beams. The sealed beam headlamps are new.

Any suggestions for this new member.
W. D. Derryberry

W.D. Put a voltmeter on the lead to the low beam connection at the headlight and see what you get. Sounds as if there might be a problem with the wiring to the low beam lights, have you checked the connection at the dimmer switch for corrosion?
gil

WD,
As Gil mentions, your dimmer switch is most likely the culprit. Check it as he states, and if need be, bypass the switch to see if your lighting improves.
mike parker

Before dismanteling the dipper switch, trace the wires for the low beams to the junction between the two bulbs. At that point there is a bullet connector that may well have developed high resistance due to corosion. If this is the case, you may well find that the insullation on the wires is crisp several inches back from the connector and need to be cut back to the point where the wires have not been overheated and new wire spliced in. If it is necessary to splice in new wire and reconnect, I would suggest using a product called Posi-Locks <http://www.posi-lock.com/>. These are a better, more positive connection for splicing wires together is high current situations. Good luck - Dave
David DuBois

Whatever it is, fix it quickly. There is no fuse in the system. I had a similar fault a few years ago - started when the car was repaired by a shop here after being rear ended. They didn't mount the cable in the rear licence plate light correctly. I kept thinking "lights are a bit dim" till the whole cable loom burnt out one night, and I was lucky to be able to disconnect the battery, otherwise the car would have gone up in smoke - there is no fuse in the lighting circuit.

$7000 later (paid by the insurance) I was back on the road.
dominic clancy

Given Dominic's bad experience, I wonder if someone has contrived to add a fuse to the lighting cicuit and how they have done so. Presumably it wouldn't be too difficult - does anyone have info including fuse size?
Tom Heath

The addition of a fuse is best done with an inline fuse placed on the supply side just before the switch.

I would use the same fuse that is used in the main fuse box - the advantage is that you always have a spare stored in the car. The fuse only blows when you have a short, not when you are under load.

This location is also invisible unless on your back fixing something else under the dash.
dominic clancy

This thread was discussed between 09/02/2005 and 12/02/2005

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