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Old 8th February 2007, 00:19   #16
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Some such funny explanations have been offered here turning entirely the laws of physics on its head..!!

The theories propounded here prompted me to do some research and brush up on my decades old physics. I thoroughly dismantled the front electrical wiring of an old M800 and studied the circuit. Nowhere did I find an electromechanical switch that did what amu said would.

It basically draws current from the battery and distributes it evenly to both headlamps on each filaments whether high or low beams. The only occassion when both the filaments of a headlamp glow is when you are on low beam and use the flasher meant for overtaking.

Going by this, I have yet to understand how if the battery goes weak, then the LH gets a priority and glows brighter than the RH. BTW, there is no mechanism to accord priority to any of the headlamps.
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Old 8th February 2007, 11:33   #17
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dg and shyam , no such feature on the indica too.
The battery went low due to alternator issue about a year back, and both lights were pretty dim. No priority thing here.
More recently the battery went kaput, so with engine off the light was weak on both sides.
There is an electromechanical switch all right, but this clicks in when I switch on headlights at idle. So when alternator voltage drops to below 12 I hear a click, a slight change in engine note and the voltage at battery terminals goes to 12.6-12.7, but no such switch for "priority"
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Old 8th February 2007, 11:45   #18
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Check if the grounding has been done properly.
Had encountered problem with Astra where left side bulb was not glowing due to faulty wire. But the parking light was working fine giving impression that light is glowing less .
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Old 8th February 2007, 12:36   #19
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Exchange the bulbs from right to left and left to right, this will help you isolate the problem, to the wiring/Battery/Relay/Bulbs
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Old 8th February 2007, 18:13   #20
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Are baba... try and understand...
The switch connects the two filaments of the right-bulb in series, and doesn't do anything with the right bulb.

Now, Power = voltage X current. Imagine each filament having resistance of 1 ohm (takes 12 A when 12 V is applied, 144 Watt). When you connect two filaments in series, total resistance is 2 ohm, and only 6A (12volts/2ohm) flows through each. Total power of the bulb = 6 Amp X 12 volts = 72 watt.

If you are still curious, connect two 100 watt bulbs in series and connect them to the electric supply, and watch the dimness.
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Old 9th February 2007, 13:57   #21
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Thats my point amu, if you connect 2 bulbs with equal resistance in series both will be dim, not one. You had mentioned that the switch somehow routes the power to one bulb and only one headlight goes dim.
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Old 9th February 2007, 14:35   #22
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Sorry for the typo. I meant -
Quote:
The switch connects the two filaments of the right-bulb in series, and doesn't do anything with the left bulb.
So, the left bulb glows on full power (only one filament active)
and the right one glows on half power (both filaments active).
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Old 9th February 2007, 14:43   #23
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amu clean connector and ground connection!! i have faced the same problem!!

and no whoever told has given u a great thought but thats not the FACT!! only case which holds some truth is resistance and wire length could/might contribute.
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Old 13th February 2007, 17:21   #24
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Question Want brighter light in cabin

Slight - but similar situation

My Accent has two small bulbs for interior light. One of them was fused and I opened the cover to see that it is 12V 10W bulb. Now I think these bulbs are too dim and I want brighter light inside.

So, what spec of bulb I should fit so that it gets brighter and doesn't blow up the fuse?

Using Watt = Volt x Amp => higher wattage means more current so more light. Is it correct?

PS: Incidentally I came accross this page and learnt that car makers are now moving to 42V system!
Howstuffworks "What are amps, watts, volts and ohms?"
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Old 13th February 2007, 20:27   #25
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one headlight going dim...
i faced this. then bought a new headlamp pair, replaced both, both were was fine. few days after same right one went dim. checked the cutout. swapped the relays, fault exsited. swapped the headlight bulbs, still only right was bad.
next changed the grounding to another location on right side, fault remains.
finally routed new wire externally to the headlight to battery and saw it is perfectly fine.
so fault was in wiring which looks absolutely fine from outside. installed a new cutout from bosch with single relay for 350/- with ceramic bulb holders and finished the story. also ended the show with three set of headlight bulbs waiting for its turn
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Old 15th February 2007, 19:38   #26
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Default Drop in intensity of headlights and lights of speedo

This is little off track to the original post. Please excuse.

I noticed my headlights and speedo light going slight dim when I turn off my engine. Is it normal ?
I don't remmember when it started or may be its normal for lights to be dim when engine is off.

Thanks..
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Old 15th February 2007, 19:49   #27
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its normal, voltage drops without the alternator feeding the electrical system
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Old 15th February 2007, 19:54   #28
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Quote:
Originally Posted by Jaggu View Post
its normal, voltage drops without the alternator feeding the electrical system
Is alternator supposed to be feeding the electrical system in a standard fittings from company factory.

Yes voltage drops when you start or turn off engine but the light is dim as compared to the running engine. I hope I am using right words.

Last edited by navdeep : 15th February 2007 at 19:56.
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Old 15th February 2007, 20:19   #29
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yup alternator charges the battery and voltage increases when running and its normal

again current is drawn from battery while engine is being cranked/started and then alternator recharges the battery, generally voltage is set at approx 14 volts where as a fully recharged battery will be at 13.xx volts

so generally the lights getting brighter (lil bit) is a simple check to see if your car charging is fine

again if the lights completely go dim (with head lights on) while cranking/starting, is a sign of bad/weak battery
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Old 25th May 2009, 14:44   #30
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Recently i have been noticing a new problem. Whenever I use any of the power window switch while the Engine is running, the sound of Engine changes a bit and the if the head lights are turned on, they dim a little bit. The same behaviour is seen even when I switch on the blower(with out turning on AC). Is this normal? or something wrong with Alternator/Battery?
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