disepyon Posted October 21, 2013 Share Posted October 21, 2013 (edited) So i did this mod awhile back and just wondering if any of you guys z does what mine does. So even after doing this mod, the rpms/idle on my 240z still drop slightly. I also have dual electric fans and it drops the idle slightly which is understandable, occurs on most cars with similar fans, but the headlight idle drop bothers me a bit. Just wondering if its just me or if others have the same problem and what you did to fix it if possible on our cars still running the original headlights. Also i forgot to metion i did the relay mod aswell for the interior/rear/side marker lights too. One more thing to say, i did upgrade the alternator to the 280z and i have an optima battery. Edited October 21, 2013 by disepyon Quote Link to comment Share on other sites More sharing options...
qlynxer Posted October 21, 2013 Share Posted October 21, 2013 I have relay mod on my headlight, parking light and even tail lights but my rpm still drop about 100 when I switch my lights on. I also have the 60amp zx alt.. I've also beefed up all my grounds and the power wire from alternator to battery but it still happens. I've considered having the alternator rebuilt to 100amp since I'm also going to be upgrading to electric fans. Quote Link to comment Share on other sites More sharing options...
Tony D Posted October 21, 2013 Share Posted October 21, 2013 Guys, your rpm dropping is a function of load being placed on the engine. You can't get around that. In some cases, voltage fluctuations can affect spark quality and contribute more to the rpm drop, but usually it's simply load imposed. I watched a 510 with a Rally 1600.... load of 150W pencilpoints on the roof. If you turned the lights on, using the master switch, and you were idling.....it stalled dead and the lights grew dim and quickly dimmer! Quote Link to comment Share on other sites More sharing options...
disepyon Posted October 22, 2013 Author Share Posted October 22, 2013 (edited) Thanks for the replies, makes me feel a lot better knowing its not just me. Yeah i also beefed up some grounds but still doesnt help. Edited October 22, 2013 by disepyon Quote Link to comment Share on other sites More sharing options...
osirus9 Posted November 4, 2013 Share Posted November 4, 2013 (edited) So I've been searching around about this headlight harness upgrade, and, correct me if I'm wrong, it seems like it is only for the 240Z? I have a 280Z and my headlights are pretty dim. I was hoping adding relays would help, but since nobody seems to do that on the 280 does that mean it already has relays in the harness? Or are my only options buying some kind of aftermarket halogen bulb? Has anybody got any info on such an upgrade? EDIT: I see that MSA sells an H4 style replacement headlight upgrade, so that answers that question. But in order to use it will the stock wiring in the 280Z be sufficient? Edited November 4, 2013 by osirus9 Quote Link to comment Share on other sites More sharing options...
Dan_Austin Posted November 4, 2013 Share Posted November 4, 2013 The problem is a lack of round connectors, so no one can make the harness as a plug in solution. If you find correct plugs in a salvage yard you can send them out and get a harness made, or make your own harness. Oddly I have not heard of anyone replacing the 280Z harness connectors with the available 240Z connectors, but that might be an option as well. Quote Link to comment Share on other sites More sharing options...
osirus9 Posted November 4, 2013 Share Posted November 4, 2013 huh, so the 240z harness is identical except for the connector? If that's true I could just cut off the connectors and splice the wires together... Or is this just not necessary on the 280z? Quote Link to comment Share on other sites More sharing options...
Pharaohabq Posted November 4, 2013 Share Posted November 4, 2013 Well There's a couple things that normally happen when you turn on your lights The Current draw on your Battery/Alternator combo is increased The engine Idle drops as more load is introduced to the engine. Datsun added a dashpot to "manually" adjust your idle under load. (this is primarily from the load the AC compressor put on rather than the lights) Aside from that, They figured at idle you're not needing bright lights anyway. Other ways to fix this include: the headlight relay mod, but likely you'll still see some drop in idle. A larger battery, allows for more draw without the engine working much harder to replace the power. Upgrading to Megasquirt with an IAC so the computer will compensate for the added load and up the airflow to keep the engine steady at idle. For brighter lights, you can use the Relay mod with thicker wires to allow more current to the lights. They should be plenty bright. Really though, If your car stays running at idle when you turn on your lights, then why mess with it? Quote Link to comment Share on other sites More sharing options...
Dan_Austin Posted November 5, 2013 Share Posted November 5, 2013 I'm not commenting about the load caused by the lights, only why the harness is not commercially available for the 280Z. The 280 does benefit from a harness, mostly from not needing to run full power threw an old set of column switches, but also from increased power available to the lights. As far as just swapping the connectors, I just have not seen that covered here. I cannot see any reason why not, and considered doing that, but I found a matching year in a salvage yard with a trashed body harness, so I did not feel guilty about chopping off just the pigtails I needed for my harness. Quote Link to comment Share on other sites More sharing options...
osirus9 Posted November 5, 2013 Share Posted November 5, 2013 So yea, just to clarify, I'm not concerned about the idle load either. I would expect my alternator to create more load when my headlights are on, I see no problem with that at all. I will also be switching to an aftermarket EMS in the next year or 2 so I'm double unconcerned. The headlight wiring is really my problem here. I'm not really that good with reading the FSM wiring diagrams and I'd prefer some kind of retard-proof instructions to just "it'll probably work... but I'm not sure" So if the 280z doesn't have a relay in the headlight harness, and the only difference is the plugs, then why doesn't anybody sell the same relay kit from the 240z for the 280z? I'm guessing there is some other reason, because if it were that simple somebody would have done it by now. Quote Link to comment Share on other sites More sharing options...
Dan_Austin Posted November 5, 2013 Share Posted November 5, 2013 The gent that makes the harnesses for MSA and sells directly on one of the other Z forums will make you a harness with 280Z connectors if you provide them. I suspect he could indeed sell the 240Z harness with a set one new 240Z chassis side connector, two 240Z headlight connectors and the appropriate wire terminals, but folks not inclined to make their own harness may balk at installing three connectors and terminals. One strong recommendation if you want one and do not want to make it, do not buy one of the universal units. They are not plug and play, and I've yet to see a positive review. The best I've seen is that it does not suck too badly... Quote Link to comment Share on other sites More sharing options...
osirus9 Posted November 5, 2013 Share Posted November 5, 2013 I also read that the universal harnesses were garbage... I'm not really worried about the connector, I could buy any weatherpak connector and replace the stock connector with it. The problem is knowing which wire goes where in the different connector. Do you know the name of the guy who makes the harnesses? Maybe he could give me some first hand info on what exactly is required to adapt the harness from the 240z to the 280z. Quote Link to comment Share on other sites More sharing options...
NewZed Posted November 5, 2013 Share Posted November 5, 2013 You can use a relay between the combination switch and the headlight fuses at the fuse box to take the current load off of the switch. The switch will then only carry enough current to run the relay. The headlights will still ground through the dimmer switch in the turn-signal stalk but at least you'll have one old resistive contact out of the headlight circuit. Your lights might get a little brighter and the odds of the combo headlight switch failing from heat-cycling go down. Quote Link to comment Share on other sites More sharing options...
osirus9 Posted November 5, 2013 Share Posted November 5, 2013 That's exactly what I'd like to do. The problem is I'm not sure how to wire it myself and I don't know why there is a kit for the 240 but not the 280, and if there are any differences between them besides the actual plug. Quote Link to comment Share on other sites More sharing options...
NewZed Posted November 5, 2013 Share Posted November 5, 2013 Unfortunately, the guy that developed the kit had a 240. Search "Zs-ondabrain" on classiczcars.com. He built the kit that MSA sells. Quote Link to comment Share on other sites More sharing options...
Dan_Austin Posted November 5, 2013 Share Posted November 5, 2013 There are a couple good wiring diagrams on here that document how to build/wire the relay harness. The headlight plug only has three wires, one 12v and two grounds. With the lights on and one headlight unplugged you can figure the wires quickly. First with a multimeter set to DC find the pin in the chassis plug with power, then note whether you have the dimmer in high or low, finally set the meter to continuity and see which of the remaining two pins is actively grounded. You now know the pin-out and color/function of each wire. If you use the weatherpak connector you can always just release the pin and move it to the right spot if you get it wrong... Electrical repairs are my least favorite part of car maintenance and I managed to build my harness in a couple of hours with diagrams found in the electrical and ignition forums... Quote Link to comment Share on other sites More sharing options...
Pharaohabq Posted November 5, 2013 Share Posted November 5, 2013 Hmm I wonder if there's a market for the 280Z plug connectors. I may be able to print those... Anyone got pictures? Quote Link to comment Share on other sites More sharing options...
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