Wiring harness compatibility/changes between years for 240Z

[rturbo 930]

I bought a 1971 Series 1 240Z that had an electrical fire in the past and has had most of the wiring replaced. The only original left is that which goes to the rear of the car, and the over head light. The new wiring is very confusing so I want to just buy another harness. From what years can I use the wiring harness from? I have one from a '72, and I found one on craigslist from a '71, although I don't know if it was from a series 1 or series 2.

Can anyone point tell me what year/series I need to get a wiring harness from to just have it plug and play?

[Arne]

Been there, done that, ended up parting the car.

But not because of the wiring. The wiring for a late Series 1 car is officially the same for only a three or four month production range. And automatics and four speeds take different harnesses. All the details that I went through when I dealt with this are in the following thread. The part numbers and build-date ranges are about half-way through the thread.

http://www.classiczcars.com/forums/showthread.php?t=19793

It may be simpler (in my experience) to replace the entire harness—all three main parts—with a good harness from a single car. That would give you a bit more flexibility in finding what you need. Done that way, you could use an earlier Series 1 harness, or even a later '71 (Series 2) harness. By '72 the changes start piling up and it gets more difficult to swap this way, and '73 is worse. If you use a later '71 harness, you'll also need the later short-tail fuse box to match.

I actually have a complete spare harness including fuse box from a 4/71 four speed car. Pretty good shape. I was planning on hanging on to it as a spare, just in case. But I might be able to be convinced to part with it, for a reasonable offer. PM me if you want to discuss that.

[rturbo 930]

Thanks for the info! For now, I think I'm going to just try to make the harness work. It doesn't need to do much, just operate my lights, signals, gauges, and engine. The car is neither complete or original. I was REALLY hoping to avoid having to take out the old harness that goes through the quarter, and that piece of the roof, since that was an absolute pain just to take out. I will let you know if I decide to buy your harness, especially if it would just plug into my remaining harness without any fuss.

Do you know what months it was that will fit my car? It's a 12/70, FWIW.

[Arne]

For a 12/70, the only ones that I can guarantee will fit with your current rear harness are the following:

Dash harness pair from 10/70-12/70

Engine compartment harness from 2/70-12/70

Both the dash and engine harnesses are different between manual and automatic transmission, the rear harness is the same for both. If your car is an automatic (and you plan to leave it that way), you'll want the proper automatic harnesses. For a manual, you can use either style. The auto harnesses will have a few things you'll ignore, and one pair in the engine harness that will need to be jumpered together.

I suspect—but can't promise—that you might be able to use the earlier dash harness (2/70-9/70) as well. I think it'll plug into what you have OK. But again, I can't promise that, so treat that as a unproven possibility.

To use the later Series 2 wiring, I think you'll want all three parts, plus the fuse box and a pair of tail light harnesses. I know the rear section is different at the tail light connectors, but don't know if the connectors at the main harness junction behind the glovebox are the same or not. So to be safe, I think you'd want to at least make certain that the matching rear section was available, if not on hand.

Man, this is deja vu...

[rturbo 930]

Thanks again for that wealth of info!

I've got just a few more questions. What is the difference between the early/late series 1, and series 2 harnesses? Is it the connectors? I think I read something about a single pin/double pin difference - don't know if that's correct or what it means since I don't know much electrical work. Is it possible that I could replace the connector on my harness such that it would fit my series 2 harness? Like I said, the car is neither complete or original - the original engine is long gone, as is the dash, and a few of the gauges, among other things. I don't mind if doesn't fit the correct series 1 gauges, or anything you can think of.

I have the ENTIRE series 2 harness from an 11/71 or 12/71 (I forget) 240z. Body, engine, dash harness, even the dash and gauges. But again... I am dreading replacing that rear piece. I suppose I could just leave it there and run the new harness in a more accessible way. I think I might try that if I can't get this Painless harness to work. In the mean time I think I'll keep my eye out for a late series 1 harness.

Edited June 18, 2009 by rturbo 930

[Arne]

First 11 or 12/71 is not a Series 2, but is a 1972 car (rarely called Series 3). The so-called Series 2 was from 1/71 through 8/71.

There are numerous differences between electrical equipment between your 12/70 and a 1972 car. It may be possible to change connectors to make it work with your existing rear harness, but it would be a considerable amount of work, including verifying that you are getting the correct wires connected to the right stuff. One small error there and you've melted another wiring harness.

To me, and I've done it twice, it's not that tough to do it right and replace the rear section so that you know for a fact that all three main harnesses are 100% compatible. I don't know why you are so reluctant to pull the rear section. Trying to use your early rear section with later front sections is just begging for future electrical problems. Far better to spend a little extra time up front than to trash yet another harness. Especially given how hard they can be to find.

[rturbo 930]

My bad, I meant series 3, said series 2... go figure. Don't know why that was in my head... anyway.

The reason I'm reluctant is because when I stripped my 280Z, taking that piece out was, for me, pretty difficult. Maybe it's easier on a 240Z? I did notice there are some small changes between the two in the sheet metal back there. Although I can think of how I'd get it back in, I can't imagine it that it's easy. I'll take your advice though and not mix/match different year harnesses trying to make them fit.

On the note of trashing another harness... I decided I probably shouldn't use my good, unmolested (I think) '72 harness, since I would need to hook up the Crane ignition that came with the car, and I'm assuming that means snipping wires. I'll do my best to make the Painless kit work, since for my application I think it would be the best choice between the two.

Thanks for taking the time to reply. Much appreciated.

[rturbo 930]

Bump! I found a 1/71 series one harness for sale. Does anyone know if this will be compatible with my car (12/70)? Also, value?

Thanks.

[Arne]

Maybe. If the car is truly a Series 1, it should work fine. But while some 1/71 cars are Series 1, most are Series 2. If it's a Series 2 harness, you'll need the matching fusebox as well. And again, I don't know if a Series 2 will plug into your existing rear harness.

[rturbo 930]

Maybe. If the car is truly a Series 1, it should work fine. But while some 1/71 cars are Series 1, most are Series 2. If it's a Series 2 harness, you'll need the matching fusebox as well. And again, I don't know if a Series 2 will plug into your existing rear harness.

It is a series 1 car, I'm almost positive. The same person has the vented hatch for sale. I'll ask and make sure.

I need the fuse box anyhow, mine doesn't have one. Only thing left from the original harness is the bit going to the tail lights.

Confirmed - it IS a series 1 car.

Edited March 28, 2010 by rturbo 930