On 7/26/2026 at 8:38 PM, Captain Obvious said:

Here's the wiring diagram I made for the early cars. The most recent version is Version 8, and. I'm not aware of any errors at this point. As far as I know, it's accurate.

Version 8.0 found on page 7 of this thread:

https://www.classiczcars.com/forums/topic/69026-1970-wiring-diagram/page/7/#findComment-676548

I think the single RL bullet hanging near your clock might be for the glove box light?

The glovebox light was coming from a different wire in this car, kind of bundled with the map light power and ground. I couldn't tell you if that's right or wrong tho.

I replaced the vintage connections spades with powerwerx power poles, and they have been very stable. the Vintage connections ones didn't look vintage anyway because they don't have the soft vinyl cover, only modern locking hard plastic covers.

Made a lot of progress... everything I want to work works (key buzzer doesn't work, great).

BUT... in testing, the last thing I did was blower and headlights. both worked fine, but... the headlights being on (hi or lo beam doesn't matter) causes a wire on the steering column to get HOT. This wire is some kind of bodge by a PO I think. It has a WL (small) line going from left stalk into a full sized red line which goes into the right stalk. Only got hot when headlights were turned on, and it got hot fast. Probably better just to look at the pictures. I disconnected battery, turned off ignition, etc.

After taking pictures, I see some burning of the 6 pin plastic holder on back of stalk. I don't think that was from today, but don't know.

What is going on with this splice? What should I do here?

Can't answer your specific question, but I would highly recommend the MSA Headlight Relay Upgrade Harness, 70-73 240Z . This is a plug and play item and totally reversable. It puts the headlight draw directly on the battery and removes from the steering stock and fuse box.

I found this site, which has a pretty clear picture of what I'm trying to show. Looks like my PO substituted a spare white-blue wire for the thicker black ground wire in this case. Too much resistance = builds up heat when headlights on = melt.

https://woodworkerb.com/home/datsun-240z-rebuild/blinker-detail/

I haven't had a chance to drive the car at night yet, looks like that was a blessing. if 30 seconds can make it smoke...

I'm thinking I get some new 10 AWG black wire, solder it to back of hi/lo beam rocker switch, replace the bullet connectors with a new pair. But do I need to be aware of anything else? Presumably the PO did that change for a reason?

I see MSA has a replacement headlight harness that takes power right from battery. not sure what changes that would require on the steering column wiring. Presumably the point is to NOT have high power for this purpose up on the steering col. Anybody have the instructions for that? I'm not super awesome at soldering, don't want to bit more than I can chew...

Edited August 2Aug 2 by Warty
Forgot link

The MSA harness is plug n play. See my post immediately ahead of yours. Also, if you plan on LED headlights you will want the MSA harness as it changes the power / ground arrangement on the headlight bulb connection. See this post for a description of what I mean.

240Z LED Headlight Wiring - Electrical - Classic Zcar Community

2 minutes ago, w3wilkes said:

The MSA harness is plug n play. See my post immediately ahead of yours. Also, if you plan on LED headlights you will want the MSA harness as it changes the power / ground arrangement on the headlight bulb connection. See this post for a description of what I mean.

240Z LED Headlight Wiring - Electrical - Classic Zcar Community

Thanks! reading...
I was trying to track down information on that harness but all the links are dead except to MSA, and it just has the one small photo. Looks like it is designed (and made?) by someone here... cool! Patience is a virtue they tell me, but man... I was so excited to see all the electrical come back on after 8 years of darkness. ah well, I'll go replace some hoses or something...

Yes, the person that "invented" the headlight wiring upgrade and the "Alternator upgrade Kit" (I'd also recommend this) for 70 through 72 240Z's is Dave Irwin. MSA has pretty much taken over the continuation of Dave's most excellent wiring mods.

If the car has H4 bulbs, that will also melt things. Dave Irwins kit is easy to install, He had a parking light kit too. Another good one. I think MSA has that one as well.

3 hours ago, Terrapin Z said:

If the car has H4 bulbs, that will also melt things. Dave Irwins kit is easy to install, He had a parking light kit too. Another good one. I think MSA has that one as well.

Normal sealed GE lights.

I ordered the lighting harness. I’ll check out the alternator one too.