Dim Headlights

[Gary L]

The days are getting shorter and the other night I ended up coming home in the dark and my headlights seem really dim. Actually, this is the first time I ever drove it in the dark. This is on my 76 2+2. I just put newer sealed beam halogen lights on it last year. I checked the voltage on my battery which I also just got last year and its at 12.20 volts. Then I checked the voltage at my headlights for voltage drop and one was only at 10.25 and the other at 10.60 volts. I have new cables on the battery and when I check the body and engine for ground there is no voltage drop. I also have new fusible links and check my fuse box for good connections. My question is, when they say to check headlight relays, where exactly are they? Or does any one have any easy to follow schematics of the headlight circuits so I can trace/check the entire run? I've got a FSM, but It doesn't seem all that clear to me on exactly where the wires run. Or does any one have any other suggestions such as maybe I'm losing voltage at the combination switch. I didn't check the voltage at the headlights with the car running, but running the car doesn't seem to make the headlights any brighter.

 

Gary

. 

[TomoHawk]

When did they start using relays on the headlamps of a 280Z?  Mine has none.  Make sure "they" know well which model of car you are referring to...

 

You have way too much voltage-drop. With the engine on, the battery voltage should be over 13V.  If you take the cover off the steering column, you can measure the voltages at the  headlamp switch, going in & out.

 

Go back and start at the headlamp bulbs, and clean the terminals properly.  Clean off the dirt and scrape off (no sandpaper) the built-up corrosion, then use a GOOD terminal cleaner like DeOxit D-100.  Don't use WD-40.  Radio Shack has cans of DeOxit D-5.  Go backward all the way to the combination switch, then to the fuse box, then the battery &  alternator connections.

Edited September 28, 2015 by TomoHawk

[SteveJ]

The days are getting shorter and the other night I ended up coming home in the dark and my headlights seem really dim. Actually, this is the first time I ever drove it in the dark. This is on my 76 2+2. I just put newer sealed beam halogen lights on it last year. I checked the voltage on my battery which I also just got last year and its at 12.20 volts. Then I checked the voltage at my headlights for voltage drop and one was only at 10.25 and the other at 10.60 volts. I have new cables on the battery and when I check the body and engine for ground there is no voltage drop. I also have new fusible links and check my fuse box for good connections. My question is, when they say to check headlight relays, where exactly are they? Or does any one have any easy to follow schematics of the headlight circuits so I can trace/check the entire run? I've got a FSM, but It doesn't seem all that clear to me on exactly where the wires run. Or does any one have any other suggestions such as maybe I'm losing voltage at the combination switch. I didn't check the voltage at the headlights with the car running, but running the car doesn't seem to make the headlights any brighter.

 

Gary

. 

Losing 2 volts is a significant drop. (http://www.headlightservices.com/Wiring.html has a graph for reference.) The drop is probably coming from the combo switch and all of the connectors between the battery, headlight, and ground. Any poor contact acts as a resistance. Resistance in serial drops voltage.

 

Unless you or a previous owner installed relays, THERE ARE NO RELAYS. (I'm not sure who "they" are, either.) The FSM is perfectly clear how the wires run. The 74-78 manuals are great for breaking down the circuits in the BE section. You need to know how to read an electrical diagram to understand.

 

Now, if you want to install relays, there are ways to do it. Probably the easiest for you would be to contact Dave Irwin, aka Zs-ondabrain via a PM. He can tell you what you need to do for him to make a relay set that will work for your car. (His kits are plug and play for the 240Z but require customization for the 260Z and 280Z.)

[Gary L]

Thanks guys. My lack of knowledge regarding electrical systems is obvious. Somewhere I heard the term relay used, but maybe its in regards to ZXs and not Zs. I did pull the steering column covers off and will be doing some checking in that area tomorrow.  Also, I meant to mention that both Hi and Low beams work fine on both sides and are equally dim (I know some guys have trouble with just Hi or Low beam not working or just one side and not the other, which isn't my case).

 

Gary

[TomoHawk]

Keep a stock of DeOxit 100 (100% strength) handy, plus a test lamp (I also have a 12V buzzer tester,) and some kind of a voltmeter or multitester (you basically only need a 12V meter.)  You will end up cleaning literally every connection on the car to really make your automobile- life  pleasant.

[Gary L]

 This morning I had a chance to pull my steering column cover off and check the electrical plugs. Everything looked clean, no corroding, etc. I still wiped them with a cleaner and now I'm up to about 10.8 volts at the headlight plug, so I gained a little. 

 

I found the following on you tube regarding a fix for low beams by grounding the red wire with a black strip and I'm wondering before I cut into my wire, if this makes sense on a 76 ? But again, both my high and low beams seem dim, not just the low beam

 

 

Gary

 

[siteunseen]

While you have the covers off you could clean the contacts in the combo switch.  It helped my 280's headlights get brighter and also my gauge lights.  This is for a 240 but it's pretty much the same.  Read through it and look at the pictures of where the carbon builds up.  It's not very hard to do, be careful bending the tabs to open up the switch though.  I broke one of mine but luckily it stayed together.

 

http://www.kamikazeracing.org/dl/ZTech/Rebuild_240Z_combo_switch.pdf 

[Gary L]

Thanks Cliff, nice article and I see other good articles listed on the index.

 

Gary

[TomoHawk]

The headlamps are wired in parallel, so what happened  to the car in the video is that the r/b wire was cut or had a bad connection with the high-beam switch, so the guy permanently grounded the low-beam side of the bulbs.  So now the low-beams are always on, even if you switch to the high beams.  I would not recommend you do it, because you will be using more current than just the low- or high- beams alone;  you will have all four filaments on, and probably overload the fuses or the switch.

 

In this situation, FIND where the wire or connection is open and fix that instead of adding cheap "fixes."

Edited October 1, 2015 by TomoHawk

[Gary L]

OK Tom, thanks, that was the kind of informative reply I was hoping for. My next move might be to take apart the combination switch as Cliff suggested and leave the wire splicing alone.

 

Gary

[TomoHawk]

First see if it is something easy to fix like a bad ground connection.

[Gary L]

I think I've pretty much checked ever headlight-related connection I can find.

 

I see BD sells a heavy duty headlight harness (10-679) for about $30.

 

http://www.blackdragonauto.com/icatalog/zr/full.aspx?Page=65

 

Has anyone else tried one of these? It says there is no splicing involved (plug/play!) and it "draws the power directly from the battery" vs the headlight switch. So I'm wondering if this would help get me closer to 12 volts at the lights? And I wonder how this integrates and works with the oem dimmer switch and headlight switch or is it then a separate system? Its difficult to tell from the photo.

 

Gary

Edited October 2, 2015 by Gary L