Captain Obvious

Now that we have fuses that are hot at all times, let me shed a little light on how I modified the headlight switch to connect to ground instead of +12. First, de-solder the two original large wires from the headlight switch. Note the two shiny empty connections on the right side: Solder on a couple smaller wires with bullet connectors on the ends. One male, and one female. Doesn't matter which one goes to which post on the switch. Snap the male bullet into the large dual bullet black ground connector and leave the female hanging: Plug the male bullet from the HI/LO beam selector stalk into the female bullet and you're done. Note that the wire from the HI/LO selector used to get plugged into the large dual bullet connector on the black wire. Now instead it goes to the female bullet to the headlight OFF/ON switch: So now, with the headlight switch OFF, the HI/LO switch doesn't connect to ground, but with the headlight switch ON, it grounds the beam selector switch. While I was in there, I also took apart my headlight/parking light switch and cleaned up the contacts, but since there are lots of other threads detailing that portion, I probably don't need to go into details here. Here's a pic though, just because. This is before I cleaned up the contact:

Might depend on the year, but it could be more complicated than you make it sound. There are actually has SIX screws holding my clamshell in place.

Haha! You sure dredged that one up from obscurity! https://www.youtube.com/watch?v=QwIQTKxiTVk Since we have permission...

So for the two versions above, one of the changes you have to make is to short around the original headlight OFF/ON switch in order to make the original fuses hot at all times. Sounds more complicated than it really is... Under the steering column, just disconnect the bullet connectors on the big W/R and RED wires from the headlight switch and then plug them together instead: Now the headlight fuses are hot at all times.

Sounds like things are going well! That's excellent. On a related note, the choke cable clamps are on the way.

I would just continue to use the one wire bullet type sender up in the thermostat housing. It's been a while since I looked at the numbers, but I believe the temperature profile for the 2-wire sensors is way wrong compared to what the gauge needs. Getting the gauge to read accurately using that other sensor would be difficult.

Great idea. Additional lighting would be a good use for the previously unused fuse. The printing and documentation would be wrong, but at least the use of the fuse would be appropriate!

Thanks for the glowing review. I've got a couple other sketches of different alternatives, each of differing levels of complexity and advantages/disadvantages. For example, a compromise on the 4-relay version above is one that uses two relays instead of four. This two relay version is simpler and would probably be what I consider the "sweet spot" between complexity and benefit. Advantages are: Uses the original fuses in the fuse block and does not require additional wires run from the battery. Original fuse block lid printing still accurate. Original fusible link still accurate as well. Fewest number of wires going to the relay block (six). Somewhat independent failure modes. One blown fuse or relay fault won't disable all the beams at the same time. Disadvantages are: More complicated than the traditional approach. Not plug-n-play. Have to modify headlight switch and jumper around headlight switch under steering column. (Much easier than it sounds!) Filament currents go through the same relay. High beams will pull almost 10A through one set of relay contacts. I really like the fact the original fuses are still used and fusible link rating is still appropriate. I also like that there is more than just one fuse for the whole headlight system as compared with the traditional approach. And other than the changes required to the headlight switch (which sound more terrifying than it really is), this version can be done with add-on harnesses which can be removed at a future date if desired. That's why I'm thinking this may be the sweet-spot between features and ease of use. When I did my 4-relay install, I had my harness ripped apart because I was also changing for the internally regulated alternator and a starter relay. Because I was in there for a couple different things I went whole hog on the 4-relay version. I figured I was in there anyway, I may as well do the best I can since I wouldn't have an opportunity like that again.

Problem is that as soon as you start making changes like that, it's no longer plug-n-play. It's just unfortunately one of the down-sides of the traditional approach. It's part of the price you pay for the plug-n-play ease of use compromise. You could (and I would recommend) that you completely remove the unused fuse from the fuse block and also replace the remaining one with a much lower amperage value (like maybe 2A). The fusible link would still be way oversized for the application, but in theory, it should only be employed with a hard power to ground short in the wiring.

I recently completed a headlight relay upgrade, but I did it differently than the traditional approach. It's a little more complicated, but I think the results were worth the effort. Basically, I used four relays instead of two so that each filament has it's own set of contacts and high currents are not shared on the same set of contacts. While I was at it, I also modified the headlight switch to connect to ground instead of connecting to power. This enabled me to reduce the number of wires needed run to the relay block. Advantages are: Uses the original fuses in the fuse block and does not require additional wires run from the battery. Original fuse block lid printing still accurate. Original fusible link still accurate as well. Independent failure modes. One blown fuse or relay fault won't turn out all the lights at the same time. Each filament has it's own relay minimizing losses in the relay contacts. High beam currents are not shared. Fewest number of wires going to the relay block (six). Disadvantages are: More complicated than the traditional approach. Not plug-n-play. Have to modify headlight switch and jumper around headlight switch under steering column. (Much easier than it sounds!) Have to run additional R/B wire out to one of the headlights. Here's a schematic of how my headlights are now connected: I took some current and voltage readings before and after the upgrade and I'll get them into presentable form and post the numbers. The results were illuminating.

Haha! Yeah, I was going to point out that while everyone else is trying to shorten their shifter, here you were trying to lengthen yours. Gotta go against the grain, don't ya!

Yes, the shifter thread is 8mm. Can't help you on the availability of any extenders though.

That's how he rolls. Let it go. Don't tell me you haven't considered the same thing on a warm summer evening...

I know there are already a bunch of different diagrams showing headlight relay upgrades, but here's my version of the traditional concept. This traditional version is the simplest and (assuming you can find the proper mating connectors) it's possible to do it "plug-n-play" with the original harnesses. Advantages are: Simplest and plug-n-play. High side switched (doesn't have any hot wires out to the headlights unless the headlights are turned on). Headlight current passes through just one set of relay contacts instead of multiple contacts in series. Disadvantages are: Have to run a new wire and fuse from the battery. All the headlight current (both sides and both high and low beams) all goes through the same fuse. One failure point. All the headlight current goes through the same set of relay contacts (maximizing power loss in the relay) One of the original fuses in the fuse block becomes completely unused (tit's on a boar). The other original fuse in the fuse block (and the fusible link) is now WAY oversized for the current new use. The writing on the fuse block cover is now incorrect and misleading as is the fusible link size and listed use.

Right. You don't need SPDT relays. A pair of SPST's work just fine for the simplest approach. I used that same sorta basic concept, but I used four relays instead of two. That way, if one side fails, I can still have a bulb lit on the other side. In other words, if I lose one low beam relay, I could still have the other side. Now, of course, the low side switching for both of low beam relays is a common fault, so if something goes wrong on my low side, I'll still lose both sides at the same time. So with my four relays, the relay contacts and relay coils are not shared fault modes between sides, but the switch and primary side wiring still is. Using four relays also means I don't run as much current through each pair of relay contacts so I don't dissipate as much power in the resistance of the relay contacts. That means I get more power delivered to the filament instead of heating up the relay contacts. I took a bunch of measurements before and after all my mods. I gotta find my numbers...

I should have been more specific. I should have said... If the car hasn't been modified by a previous owner, then the electric fuel pump is mounted on a bracket back by the tank. Now, of course, if a previous owner mounted a second electric fuel pump up in the engine compartment and wired it in somehow, then there's no telling what electrical modifications he preformed to make that possible. As for the mystery connector in question, take a look at the upper left hand corner of the 260 wiring diagram. There's a connector with yellow wires that says "To Pressure Sw." And take a look at pages AC-5 AC-12 and AC-13 of the 260 FSM. They talk about the high pressure cut-off switch there. No telling if that's what that connector is for NOW, but I think it was ORIGINALLY for the AC system.

The fuel pump uses the same style of connector, but the one you found in the engine compartment is most certainly NOT for the fuel pump. On the 260, the electric fuel pump is mounted on a bracket back by the tank. I don't have a 260 anymore to double check, but I believe the connector you found in the engine bay is for the air conditioning system. High pressure cut-out switch maybe? Mounted on the receiver/drier?

Hi Tamo, Actually I think the drawings in the FSM for the alternator section are pretty good. Are you having a problem with yours?

I've never seen a center off relay like you described. The relay upgrades I've seen floating around have one side of the relay contacts always hot, but I don't see that as a problem. None of the three wires that go out to the headlights are hot unless the relay is closed. I guess I don't see much difference between one side of a relay always hot and one side of a switch on the stalk always hot. One side of something is always hot. One question... You said the relay upgrades you've seen use SPDT relays? I don't think they have to be double throw. SPST relays would work just fine. Maybe it's just easier to find SPDT? I'll draw up what I did. It's a little different than what most people do.

My one kid is eyeing my cycle. "Can I have a cycle when I get older?" I can't legitimately tell him he can't with mine sitting there... I tell him "After you're out of college and living on your own, your mom can't tell you "no" anymore."

Well the main reason I'm going is to socialize and see cars. A riverboat cruise would be cool, but it would probably be lost on me because I'd be yakking about the cars anyway and not looking at the sights. Tentative plans are to fly in on Thursday. Not sure what time I'd get there, and not sure how to get from the airport to the hotel. I'm assuming there's an airport shuttle. And fly out on Sunday after the festivities are over. The shuttle between the hotel and downtown is convenient, but not worth a hundred bucks. I wish there was a cheaper registration option for people who weren't bringing a car and only wanted to attend (but not even eat at) the awards ceremony. And yes, someone needs to organize a couple "Classic Zcar Club" events so we can all meet up. I heard that SteveJ was in charge of that... Remind me to avoid the hotel bar while they're doing karaoke. Philip, You two will be in your S2000, right? You're not bringing a Z are you?

Seriously? He towed it from MO to NJ for you??? Wow! A laminated wiring diagram included with the car is never a good sign. And I like the multiple generations of cycles. Yours and the kids? You two ride together? Good luck with the project. Looks like a great starting point.

2050-Z, Everything sounds like it is working exactly as intended except for the click and then completely dead. And as Zed Head suggested above, that is probably as simple as bad battery cable connections. The charge light is supposed to light up if the key is on and the engine is not running. The beeper is supposed to beep six times or so before stopping. Clean your battery terminals and cables and the "click-dead" thing should go away. As for the two small wires hanging down below the steering column, I believe those two used to connect to your ignition lock. They are used to beep the beeper when the key is in the ignition and the door is opened. A reminder that you have left the key in the ignition. If you removed the ignition lock portion, you had to disconnect those two wires to get the lock out of the car.

So I think I have the green light for ZCON 2015 although I'll probably fly in instead of drive. I'd love to have my car there, but I just don't think I'll be able to swing that. So without entering a car... Do I need to officially register? About the only thing that sounds like it might be a problem is that I'd really like to go to the awards presentation at the end. I don't need food or drink... I just want to sit with some friends whom I've never met and have some good conversation. Patcon and siteunseen, you guys are going without cars and without registering? You guys got a plan for the end presentation?

Oh, and something I forgot to ask about... You mentioned above that you had not noticed any ears on the tail lamp connectors, but what's confusing to me is that the photo you posted HAS the mounting ears. Did you take that pic or just nab something similar (but not quite identical) from off the web?