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Why are headlights so dim?


Guest JAMIE T

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Guest JAMIE T

I have to drive at night with my high beams on so I can see the road, and still can't see that well then. If I upgrade to the Hella H4 head lights, what else do I need to do(other than add a relay)? Will this help or will these lights be dim also? Is it the wiring or the low output charging system that makes these cars have dim headlights? Thanks guys.

 

Jamie

Deathstar

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It's probably the wiring - the wiring harness is pretty old at this point, and the contacts in the light switch, as well as all of the connections in between probably are somewhat corroded, causing a much larger voltage drop than when the car was new.

 

Check the voltage at the headlamp, preferably between the contacts on the lamp itself. I wouldn't be surprised if you were only getting 9 or 10 volts at the lamp. If this is the case, wiring those relays for your stock lamps will probably help quite a bit. Also, this will make it pretty easy to upgrade to the H4 lamps later, if you want.

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Yup! Do what Tim said. I did some experimenting on stock wiring headlight output, and 'cleaner' wiring for the headlights, and there was a world of difference. I wish I had measured the voltage at the time though. I have relays just sitting waiting for my car to have headlights again. icon_smile.gif

 

BTW, I don't think I'd run H4's without relays. Asking for trouble IMHO.

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i think all of us with stock headlights have this problem, i like to think that the lights are for our benefit, but so that people can see me at night and not crash into me!

the h4 is a good upgrade, but it will probably burn your switch out, and that thing costs 100.00 new, you could get one from the junkyard for a lot less(cough) put it in your pocket) (cough)

what i plan to do one of these days is stick two hella off roads in the grill and use a toggle for them, id either run one or the other, headlights in town, and once i hit the freeway, switch to running lights and and run the hellas, lets go wangana middonite hardcore racer!

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ARGH! SuyperDan please post my headlight relay upgrade tech article back!

 

Whew, okay. Here's the deal - power flows from the battery through the lights all the way through your switch. the switch ages, brushes corrode, it all gets old, and the switch will even begin to heat up. Do NOT simply upgrade to the Hellas! Get an upgraded relay harness. I used the Painless Wiring one and it was a mistake - too expensive but very nice. There's another company that I mention in my tech article that has a BETTER harness for our purposes who's name I don't recall (Dan please...).

 

Do this harness upgrade FIRST. I'll bet that your old lights look like new when you're done. I've got Hella H4s in my car and the difference was night and day. No longer was my brand new switch BURNING but my lights were WAY brighter on LOW beam. High beam is incredible. I got probably 4 volts to my lights by doing this and you may get even more if you're are in worse shape. Trust me, it's easy and worth it - buying a kit makes it fast too. I prmise that if you've got voltage coming out of your switch and a decent alternatorbattery that you'll be shocked at the brightness difference. It's really noticable. If you goto higher wattage bulbs now you'll simply burn things up, with the lowered voltage I know there's high resistance in your wiring and I know that burning the harness would occur.

 

Do the harness first, if it's not bright enough do the lights next. I only wish there was some way I could have documented the difference easily. With the rash of headlight questions lately I really wish I'd kept a backup copy of my tech article. If Dan can't find it I'll try to reconstruct it from the photo's I've got and double check for my text. icon_rolleyes.gif

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Guest JAMIE T

Thanks guys. Installing the relays is way easy, I probably have some laying around here from a major stereo/alarm install. I will also clean all of the connections and chase the wires for bad sections. I am definatly not going to run the H4's without relays, thats a fire waiting to happen.

 

Jamie

Deathstar

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Whew, thank you Dan! Maybe we can polish it up some with the experience others have gained from doing this swap since my writeup...

 

Make sure you use QUALITY relays when you do this - good wire too. The Painless wire is awesome and sold in Jeg's. The relays will be under a pretty heavy load for possibly hours at a time and th elast thing you want is to "lose" a relay while driving. I'd urge you to use two exact same relays too with a holder for each. This way if the low beam fails you can yank the low beam relay and swap them in a pinch. I've built a little relay tray for my car to handle the fan and headlights - unfortunatly they aren't all the same and I worry a little. icon_rolleyes.gif

 

With a couple of relays and a little wire you shoudl be set right up. Please let me know how it goes! icon_smile.gif

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  • 1 year later...

I know it's probably on the wiring chart, but...

 

where does the ground for the headlights go? Mine aren't that dim, but could do with some boosting.

Should I run a new ground wire for the chassis? Can I just clean the connections? You can probably shine up blade connectors, but the ones for the headlights are pins/round. I thought of using "CLR" to try to 'de-corrode' the connectors.

 

One day (I'm a chemist/scientist) I'll figure out how to regenerate conductors with some kind of reverse current thing. It's probably like that electronic rust protection.

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Search on headlight and relay. Probably in the Misc Forum. I know I've laid out the circuit (maybe in words only) here before.

 

But the grounds run back to the hi/lo beam switch, on the 240Z, anyway. It's the screwiest (new word!) circuit you could imagine. Truly a stupid design.

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Guest Anonymous

Just another idea.. if you hit the brake pedal and the head lights "go dim" it is a worn Datsun ignition switch. The worn inition switch cannot route enough juice thru causing the headlights to be dim and even dimmer when the brake/stop lights are activated.

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...which is why RELAYS are such an important upgrade for anything that pulls more than a couple of amps in the Z. I have MANY relays in my Z, even to the HEI distributor, with a nice fat wire coming from the battery cable on the Ford Solenoid/Switch.

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Is the wiring on the 280Z's any better than the 240Z's in this respect, or is it the same crappy setup? I have a 78 that is sitting right now waiting on me to get started with the restoswap. Unfortunately it will have to continue to wait a little longer.

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Guest Carlissimo

I just fininshed putting two small 50 AMP accessory relays on the radiator bulkhead of my 73 Z. I ran 10 gauge wire from the battery forward thru one relay to the lights. I ran a short 10 gauge from the chassis ground at the bulkhead thru the second relay to the lights. The second relay swithes the ground and thus swithes lights between low and high beam.

 

My lights used to dim when the fans kicked on. They even dimmed when I hit the brakes. In fact before, I had about a 50% success rate of them coming on at all !

 

Now they are great. They come on every time, real fast, and they are real bright. They don't dim at all either, even at idle with the fans on. To be honest, I didn't really know how bad they were until now...

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