Hello all,

I’m thinking about replacing my engine harness at the moment, Part# (N3A1-18-05ZD) which is the Canadian part number and No longer available.
Compared to the USDM part number (N3A1-18-05ZG) which is available.

I checked the wiring schematics and found the below pictures which I highlighted (Canada).
1) one wire seems to be grounded from 2F ECU.
2) another one going to the DRL control unit.



Anybody encountered this issue before?
If I install a USDM harness, I’m I going to run into an issue, other than probably losing my DRLs?

I did contact Wiring Specialities regarding their harness, and they couldn’t confirm compatibility to a Canadian RX7.

Any help is appreciated.

 

there is a supersession, N3A1-18-05ZD is superseded by N3A1-18-05ZG, N3A1-18-05ZG is the current part number.

and wow that is kind of big

 

When you said replacing the "engine" harness, I assumed you meant to say the "emissions" (EM) harness that connects to the ECU, which matches that current part # N3A1-18-05ZG. The "engine" (E) harness is another subject. Anyway, if those two ECU wire connections are the only ones that are different in a Canadian spec FD, I don't think you'll have any issues. One of them runs exclusively thru the front (F) harness (pin 2F, black wire to ground), so that one is fine presuming you still have the original unmolested (F) harness. The other, pin 3J (L/G wire) on the (EM) harness runs thru connector X14, to a (Y) wire in the Dash (D) harness, and from there on to another (Y) wire on the Front (F) harness via connector X07 to the DRL control in CPU#2. Since the "G" revision of the EM harness should retain the same (L/G) wire to pin 3J that terminates in the EM harness side of X14, you're good there too.

 

Wow, thanks a bunch.
Now the question is whether to go with OEM or WiringSpecialities.
TBH, I’m leaning more towards WiringSpecialities due to their high temp resistivity and durability.

 

Yes I believe I meant the EM, which supplied to all the rats nest solenoids, tps, water sensors, air pump, etc.
Also, yes the front harness is unmolested.

 

One thing to remember - you can't compare 100,000 mile OEM parts that have been baking for 30 years over a hot pre-cat to new OEM. That nice aftermarket harness may be just as crap in 30 years.

Also 90% of the harnesses I've worked with were electrically fine. They needed new good tape to replace tape that was failing and peeling off and replace a few broken connector shells. That done it looked and worked great.

If you do choose between new OEM and new aftermarket I think really both will last about the same amount of time.

Dale

 

Dale is right on WRT comparing a new OEM harness to an aftermarket one. An OEM harness is a well known entity that typically lasts 30+ years in a stock FD. When they do fail, it's typically at the connectors/wire runs that are exposed to the most heat - over time and lots of heat cycles, the insulation & connector shells gets brittle and break, the copper wire corrodes under the compromised insulation, etc.. So the life of any aftermarket harness will depend greatly on how well it's constructed and what kind of materials were used in its construction. You can extend the life of either type of harness by taking steps to reduce the wiring's exposure to excessive under hood heat. That can be as simple as popping the hood open whenever the car is garaged at home to help dissipate the heat to tackling some reliability mods (i.e., replacing the pre-cat with a down pipe)

 

Honestly my harness is fine for 30 year old car.
despite the peeling tape, and repaired air pump connector.
I thought the aftermarket harness, might be less in diameter and more flexible.

Thanks for tips

 

Aftermarket costs half as much as OEM, though.

 

I think OEM costs too much in the US.
I got a quote for OEM harness from Japan for $980 excluding shipping.

 

Remember the Japanese harnesses will be for a RHD car. There is a difference.

I believe you can make a RHD harness work in a LHD car but it's far from plug and play. The ECU is on the opposite side of the car and the white and blue connectors by the ECU are different sized and have a different pin layout.

Dale

 

I had the same thought when I did search the Part number, I was worried about the length and orientation.
But found that the JDM P# N3A7-18-05ZG, and clearly seen on the diagram that it’s routed passenger side in JDM RX7s.

Not sure thought if they also have supersession history for JDM series 6.

 

there is but i don't have a neat scroll like i do for the US.


and as you've pointed out, N3A1 is for a North American LHD car
N3A7 is the early RHD Japanese Market car (they would say normal, lol)

in Mazda's system, the first 4 digits tell you what the part was designed for
N3 = 13B rotary, in general
A1 = is the US spec 1993
A7 is the Japan Spec Version 1 (1992)

18 is the system or section of the parts catalog. 15 is cooling, 16 is the clutch, 50 is the bumper, etc etc
the wiring harness is kind of an odd one, as 18 is engine electrical, but its in 67 with the rest of the wiring

05Z is the specific part. 16-410 is a clutch cover, 15-200 is a radiator, etc etc. if there are two parts, the bigger number is the left, for instance
57-100 is a right front seat, 57-150 is the left, etc

and then there is a letter for the supersession. A-Z, except o, q, and i. they look too much like numbers.
sometimes there is a difference in the part, sometimes its the price, sometimes it seems like its the Purchase Order for a new batch.
so sometimes its important, sometimes not. Mazda doesn't keep old parts hanging around either, so the only thing available is the current number

there is an additional field for a color code, if applicable. so FD05-57-150D-02 is a black leather seat, FD05-57-150D-17 is red leather, etc