olie05 Posted August 9, 2007 Share Posted August 9, 2007 I recently rewired my ghetto 2-switches-in-the-console-for-headlights to work with the stock switches for headlights/hibeams. Along the way I discovered a problem. I noticed that if I follow the wiring diagram on my car, my "high beams" are significantly lower in brightness than my Low beams. I verified the issue with beam pattern. On low beams there is a distinct cut off line, along with a brighter beam, however on High beams, there is a wide beam pattern that is very dim. Note: The bulbs are three prong, common, hi, lo. I wired the bulbs to be 12v positive on the hi and lo, and grounded the common. The factory does it the oposite, where the lights get the power from the common, and the hi, lo are switched to ground. Could that be part of the problem? As far as I know, light bulbs work exactly the same if you run the current the other way. -Oliver Quote Link to comment Share on other sites More sharing options...
stagefumer11 Posted August 9, 2007 Share Posted August 9, 2007 direction of the current should not change the output on the bulb. You might have a bad ground somewhere. I had low output with my factory wiring, So made up a external harness with relays and used the old harness as a switch only. Improved the output hugely over factory. I'm running switched 12V also, Not switched ground Quote Link to comment Share on other sites More sharing options...
olie05 Posted August 9, 2007 Author Share Posted August 9, 2007 Its can't be a grounding issue because as of now I have the headlights to be common grounded. In other words, I only have one ground per light. Since the low beams work just fine, it's either going to be a voltage drop somewhere in the power wire, or a bad bulb. I have never heard of a bulb going bad and still working though. Quote Link to comment Share on other sites More sharing options...
Nigel Posted August 12, 2007 Share Posted August 12, 2007 Note: The bulbs are three prong, common, hi, lo. I wired the bulbs to be 12v positive on the hi and lo, and grounded the common.-Oliver If my memory serves me correctly, the markings on the headlight connector (hi, lo, com) don't actually correspond to the correct wiring. I think I may have posted about this either here on on zcar.com. I'll have a look and see if I can find my post... Nigel '73 240ZT Quote Link to comment Share on other sites More sharing options...
Nigel Posted August 12, 2007 Share Posted August 12, 2007 Ok, I found my post on zcar.com. It seems that the headlight connectors that I was looking at had "pass" and "drive" printed on them, and I was expecting "pass" to be the high beam and "drive" to be the low beam, which turned out not to be the case. So that may not be of much use to you. Are your headlight connectors clearly marked "Hi" and "Low"? Even so, maybe you should try a different combination. A friend of mine had his headlights wired in such a fashion that he had the same problem you did. The hi beams were dim compared to the low beams. It turned out that whomever had rewired the headlights previously, had reversed the low beam and common terminals. Consequently, when the high beams were switched on, the power was going through both the high beam and low beam fillaments in the bulb to reach common. I hope that makes sense... Nigel Quote Link to comment Share on other sites More sharing options...
WizardBlack Posted August 28, 2007 Share Posted August 28, 2007 Ok, I found my post on zcar.com. It seems that the headlight connectors that I was looking at had "pass" and "drive" printed on them, and I was expecting "pass" to be the high beam and "drive" to be the low beam, which turned out not to be the case. So that may not be of much use to you. Are your headlight connectors clearly marked "Hi" and "Low"? Even so, maybe you should try a different combination. A friend of mine had his headlights wired in such a fashion that he had the same problem you did. The hi beams were dim compared to the low beams. It turned out that whomever had rewired the headlights previously, had reversed the low beam and common terminals. Consequently, when the high beams were switched on, the power was going through both the high beam and low beam fillaments in the bulb to reach common. I hope that makes sense... Nigel I've run into the same thing before. You somehow have it wired that both high and low are mixed in and you get extremely low light output. Quote Link to comment Share on other sites More sharing options...
RB26powered74zcar Posted August 28, 2007 Share Posted August 28, 2007 I have the exact same issue. The low beams are nice and bright, but once I flick on the high beams, they go dim. This is after a friend and I installed a complete new EZ Wire harness thru out the car. I just haven't dug into figuring out whats the prob yet, so I'm glad I saw this post. This is prolly exactly why mine are acting this way.... Thanks for the tip guys!! Quote Link to comment Share on other sites More sharing options...
rejracer Posted September 7, 2007 Share Posted September 7, 2007 Make sure all connections and wiring is good. I would pull the bulb from the car and with the brites on check the voltage at each pin. If there is say 10v on one pin, and zero on the other two then you are schematically good, but have a power supply issue and are risking a fire. If you check voltage at the pins and find say 12v(full voltage at one pin, 7 volts on another and 0volts on the last then you know you have 1 of 2 issues. A. you are running the current through both filaments. The light bulb wired in this matter becomes a voltage divider. To check for this remove the 0v terminal from the circuit (unplug it by removing it from the socket) after doing this if you have no light whatsoever then you were running it through both filaments. Also if you remove the 7 volt terminal (more than zero but less than 12) and there is change then it proves again that you are running the current through both terminals. There is no risk of fire in this situation. B if when you remove the same wire as above and there is no change then you know you have a ground circuit issue. if you remove the 0 v connection it will make no difference. If you remove the partial voltage connector you will get nothing. This too is a fire risk. Check all voltages referenced to the mother of all grounds. In engrish this means connect the negative terminal of the VOM to the negative battery terminal. Do these tests in order. All of the above is assuming A side switching (switched positive not negative). Quote Link to comment Share on other sites More sharing options...
olie05 Posted September 8, 2007 Author Share Posted September 8, 2007 Maybe i'll get off my lazy butt and go check the wiring... But I wired the bulb harnesses (from the stock sealed beams) as per the factory manual, only reversing the polarity. Now with the H4 lights it seems to be Doing Problem "A" where it is running voltage through two filaments in series. Quote Link to comment Share on other sites More sharing options...
olie05 Posted September 8, 2007 Author Share Posted September 8, 2007 Yep that was the problem. The ground (my common) was connected to one end of the filaments, so when the power was applied on my hi beams, the current would run through both filaments. The solution: Tested with two wires off my battery to see which pins were the dimmest (running through both filaments) and made sure NOT to have those together in the new wiring. I'm about to go find a nice dark road to drive on and test the new (to me) hi beams! Quote Link to comment Share on other sites More sharing options...
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