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how to plug hella H4?


mikec

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hey guys, was wondering if anyone of you other guys have tried running H4 low beams in your trucks? i am having trouble plugging them to make the lights all operate properly; i can get them to osculate or have all four run unevenly (low beam switch on only). changing to plug orientation on each light has a unique pattern it seems....

 

 

35k7pqu.jpg

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Your headlights gain power through the switch. There is a relay which switches the ground for either high or low.

 

It should be possible to relay just the lows. Im getting dizzy looking at it, but I will try to add a diagram soon for hooking up relays.

 

I have included a Wiring Diagram from a 81 720, best I could find... Figure it is close enough.

wiNic.jpg

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Oh. My. Lord.

 

i'd prefer to run as little new wire as possible, I was hoping to just run the low beam switch to a relay running power from the alternator out to the h4s, leaving the highs on the factory sealed beam circuit.

 

I'll try and dissect that diagram later tonight.

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okay, so far i've followed (+) right low (R/Blk) and left low (R/Blu) backwards to fuses after splitting from a common (R/G) back to #2 light switch. that switch runs from the battery via a green fusible link/red wire.

 

(-) right low runs a red wire to a relay and ground, as well as #19 'printed circuit' that also eventually runs to grounds.

 

so i guess at this point, i'm wondering if i can run my relay at the R/G common low beam and replace the R/Blk and R/blu afterwards with heavier gauge wire the rest of the way powered through the relay via alternator tap? or would it be simpler to run separate relays for each L/R closer to the bulbs?

 

as for the ground, would that relay need to be upgraded as well, or would the factory setup suffice?

 

*head hurts*

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Get two of this relay. This relay has two pin 87, and does not have a pin 87A. You can get then in two or three days from Summit racing.

Relay.jpg

 

You can wire the coil of the relay, pins 86, and 85 to the original headlamp plug. Wire one relay to come on (click) with a low beam headlight.

 

Wire the other relay to come on (click) with a high beam headlight.

 

Wire fused battery power to pin 30 of both relays. Get new plugs for the H4 headlamps. Ground the common connection on the four headlamp plugs. Ground back to the engine, or alternator frame, use 12 gauge wire.

 

One relay will be the low beam relay. You have only two lamps on with low beam. Run one wire from pin 87 of the low beam relay to the right side low lamp, and the other wire to the left side low lamp.

 

On the high beam relay, once you get the wire for the right side, and left side in place, make a "Y" splice, and run the two wires from the "Y" to each high beam lamp.

 

This is what the pre-made harness in the last post is. If you build it, you can choose to use heavier wires in it. But if you are not good at soldering, or making electrical connections, it is probably better just to go with the pre-made route.

 

It is probably more important to use relay on the high beam lights. Twice as many lights, twice as much current.

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I just installed a cheap easy relay kit in my 520. Black dragon sells one advertised for Z cars that works perfect (a 2 light version) it is identical to the 4 headlight version I used. Took 5 minutes to install. The lights were dim and yellow at first, after they look real bright.

It's $30 here... http://www.blackdragonauto.com/icatalog/zr/full.aspx?Page=65

I found the 4 light version on E-Bay for $15. Good luck.

http://community.ratsun.net/topic/23861-someones-old-my-new-520/page__st__20

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