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Light problem driving me nuts!

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Basil

Basil

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Ok, so my headlights stoped working some time ago and now I'm finally trying to figure out why. I discovered that one sealed beam was shot, so I went ahead and bought two new units thinking that might be the problem. Nope - even with two new sealed beams I still have no headlights. Now what is really strange is, when I unplug both headlights from the plugs, and measure the voltage at the plug, it seems to be working fine on both sides. I get 12v between black and the Blue/red with low beams and 12v between black and blue/white on high (might be the other way round, but the point is, it seems to change when I hit high-low beams. BUT - when I plug in EITHER or both of the sealed beams (new remember), not only do the lights NOT work, but the high beam light on the speedo stays on regardless of whether I have high or low selected. This sounds like a short somewhere - but where? I am heading back out to continue trouble shooting this odd problem. Going to pull the switch (its new also) on the steering column and make sure noting funny is hapenning there. Wish me luck and if you have nay ideas, please post them.

Cheers,
Basil
 
Hello Basil,
it sounds more like a poor (very) earth. As you obviously have a meter, plug the light units in and check from the live to the chassis, or better still back to the battery negative. If the voltage is not there under load there is a poor supply connection, (main or dip switch). If the voltage is there then you should also have 12 volts or thereabout on the black. If you have, it is definitely a lack of earth connection or in your part of Torquay, ground.

Alec
cheers.gif
 
Originally posted by Basil:
seems to be

Basil
If you have B+ at the wires on low, and then switching to high, get B+ at the other feed wire, then you're good there. Try building a temporary very good ground jumper and doing it again. I'd be very surprised if this is not your problem. Be sure the ground jumper goes directly back to the battery so that you've eliminated any chance of a bad body ground. If the lights work, then start tracing bad ground wires. In almost every instance when something odd happens electrically, it is a poor ground connection, at least in a 12v circuit; things get a little trickier in the new 5v lines.
Good luck, and come back with more info if that doesn't work.
Click to expand...
 
Basil,
All sounds like good advice and I think everyone is on the right track, however, you also want to confirm that your new bulbs are good, (jump them from battery). Ive seen them NFG right out of the box.
 
Vague ramblings follow without much thinking.

Poor earth/ground on the actual light unit results in sneak current attempting to ground to best available ground which in your case may be back through the high beam indicator in the dash.

Suggest running sep. ground lead off lights to body as already mentioned.

Switch may be faulty.

Can't think that anything else would effect any of this.
 
Thanks for all the suggestions (I have been coming in and checking). Update - I pulled all of the bullet connectors out of the female connectors, for both the high and low circuits, then I used emory cloths and cleaned both the male and female connectors and plugged all back in. BETTER! Still a slight problem - now I have low beams, and when I pull the lever towards me (to flash the brights), the brights work. BUT - when I push the stalk forward (to turn the high beams on), the right high beam goes on, but the left light goes out completely (i.e., the high beam circuit on the left side only works when I "Flash" the lights. Almost has to be a bad connection at one of the bullet connectors. Stay tuned - film at eleven!
tongue.gif


Basil
 
Update - my lights are working fine now. I just had to clean up all the connections. But now - my stupid water pump is leaking! Arrrggg!! Oh well, not a big problem, but kinda frustrating since I was hoping to drive my Spit to work tomorrow
frown.gif


Basil
 
<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Originally posted by Basil:
Update - my lights are working fine now. I just had to clean up all the connections. But now - my stupid water pump is leaking! <hr></blockquote>

See? Should have settled on the broken headlights
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<blockquote><font size="1" face="Verdana, Arial">quote:</font><hr>Originally posted by aerog:


See? Should have settled on the broken headlights
smile.gif
<hr></blockquote>

Besides, it probably ran hot anyway
violin.gif
 
Aloha Basil,

I can feel your pain! I agree with many that have said the most common problem with Lucas electric components is a faulty path to ground. I think I have the same problem in my MG, the turn signals and wipers don't work immediately when energized. It's as if the electricity is moving very slowly through the circuit. I suspect if I clean up the ground contacts it will fix the problem.

Since it is often said in jest that Lucas invented darkness, perhaps your headlamps had the polarity reversed and they were absorbing light in lieu of emitting light. Congratulation on fixing the problem.

Safety Fast,
Dave
 
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