DIY: Aftermarket Seats Installation

V1H

This is an install guide for my BRAUM seats, but will apply to other aftermarket seats, too.

You will loose the factory seats motorized seat control and the seat heater function.
You will save 4 kg weight per seat

As you may know, I ordered:

• pair of BRAUM Racing Elite-X seats, Red Komodo Edtion [#BRR1X-RDRT] that include dual lock sliders
• pair of Planted Technology seat brackets [#SB096DR and #SB096PA]

I also needed to get extra hardware (per seat):

• four M8 bolts and nuts for the Planted seat bracket
• one 7/16" UNF nuts for the factory seat belt buckle mounts
• one 2R2 resistor to terminate the SRS harness (2.0–2.2 Ω is fine, wattage is uncritical).

Passenger seat extras, only:

• one 15R resistor (11–20 Ω is fine, wattage is irrelevant)
• Nissan Fog Light switch, or any toggle switch of your choice

Driver seat
1) The factory seat removal procedure is found in the workshop manual page SE-71. Basically:

• Remove headrest
• Slide seat forth/back to unbolt 2 floor bolts behind/in front of seat (M14 socket)
• Disconnect battery and wait 3 mins
• Lift seat and unplug OEM wire harness, i.e. 3 plugs: SRS (yellow), seat belt sensor (small white), motor/heater (big white)
• Carefully take out the seat

2) You may now test fit the seat bracket, which should line up with the 4 factory bolt holes.
Note, here in the U.K. the driver side seat bracket is labelled with 'Passenger'.
But don't install it! The seat bracket needs to be bolted onto the Braum seats, after you first installed the sliders.


3) Turn over the Braum seat and bolt on a pair of sliders, then clamp in between a handle. The handle must face forward and release the lock mechanism by pulling up (when seated), not down!
The sliders have no easy orientation, so look closely at my photo:


4) Use the four extra purchased M8 bolts (facing up) and nuts (facing the floor) to bolt the seat bracket onto the sliders as per photo:


5) Undo the seat belt buckle from the factory seat and bolt onto the seat bracket, reusing the factory 7/16" UNF bolt together with the extra purchased 7/16" UNF nut:


6) Route the seat belt sensor harness under the seat, which I secured with the yellow factory clips.
As for the yellow SRS plug, you could splice into the factory harness before the yellow female plug (photo from step 1) and terminate it with a resistor. Or, like I opted to do, cut off the yellow male plug of the OEM seat and reuse it and terminate after that:

The termination is done to satisfy the ECU that will look for the presence of a 'working airbag', which is presumably a heater element (the SRS charge igniter) with an electronic characteristic identical to a 2.1 Ω DC resistor in series with a small inductance of 2.6 µH.
I appears, from what ppl did before, the ECU is successfully fooled by a simple 2R0 or 2R2 resistor.
I ended up ordering a 2R ±1% 3W resistor and a 2.7 µH ±20% inductor - probably overkill. (Would only matter if the ECU test signal was AC rather than DC where impedance deviates from resistance as frequency goes up. Bloody scientist in me )

7) Place Braum seat into car, reconnect 2 of the 3 harness plugs, bolt down the seat bracket onto the floor. Then reconnect battery if you're done here.


If you get an SRS DTC (Airbag dash light) you can reset it with this procedure.

Passenger seat
The passenger side seat installation is identical, except you have to also deal with the factory passenger occupancy sensor.

I’ve seen people transferring over the occupancy sensor by slicing up the factory and aftermarket seats, but with mixed success rates. The occupancy sensor is a bendy pressure sensor that changes resistance as weight sits on it. But that actuation is sensitive to the placement of the sensor and the cushion type/thickness above it (after all, it’s clearly tailored to the factory seat characteristics).
I therefore decided to not carry over the occupancy sensor but use a fixed resistor and toggle switch to emulate the sensor actuation for empty/child and adult occupant.

The factory seat's passenger occupancy sensor, it turns out, is less sophisticated than I anticipated. As shown in the photo, the sensor simply splices into the wire from the seat belt buckle:

I measured the actuation of the passenger occupancy sensor. It acts less as a continuously variable resistor and more as a simple switch, which discriminates between two possible states, only:
I) IF seat is empty or occupied by a light weight person (child) THEN resistance = high (150 MΩ – 1 GΩ)
II) IF seat occupied by adult weight THEN resistance = low (~20 Ω – 11 Ω)
The transition between I) and II) is abrupt. As I slowly loaded the seat with body weight, resistance just jumped at one point from 150 MΩ to a couple 100 Ω and then quickly approaching 20-odd Ω. The passenger occupancy sensor can be approximated by a binary resistance state, HIGH or LOW. I suspect the sensor acts as Pull-up/Pull-down resistor in a simple logic gate circuit to provide the ECU with a Hi/Lo voltage signal.
While the sensor states might well be approximated by infinity (open circuit) and zero (short circuit), I decided to emulate the unoccupied state with o.c. and the occupied state with 15 Ω, via an ON-OFF toggle switch.

I made a drawing to show the simplicity of all the affairs, no magic or complexity here. In fact, one could even completely ignore the lost Passenger Occupancy sensor, leaving its connector disconnected. The car would merely never nag you to fasten the seat belt when the passenger seat is occupied. Note, passenger SRS is unaffected, and always active in the 370Z. After all, the system cannot distinguish between an empty/child seat with the seat belt unbuckled (R = high) and an adult occupant with the seat belt buckled up (R = high):

So, I carried over the seat belt buckle with its wire harness to the Braum seat. As before, I salvaged the yellow SRS connector from the factory seat and terminated with a 2.2 Ω resistor (actually I used a 2.0 Ω resistor in series with a 2.7 µH inductor, but don't bother).
Finally I salvaged the white passenger occupancy sensor connector (cut off the sensor's plastic wires) and soldered on a white 2-wire lead, shown here:


When I installed the seat with bracket I ran the white lead under the carpet into the center console, since I wan to use a Nissan Fog Light Switch (Ebay) by the cup holder as my toggle switch for an OEM look.


The switch is still in transit.
Once there, I'll have to solder on the 2 wires with the 15 Ω on one of them.
I'll also attach a little custom sticker to cover the fog light symbol.

Finished Install Pictures:

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501 BHP, 590 Nm (422 rwhp) AAM TT+I/Plenum|CJM S1 FRS|C/Clutch Stage 2|RJM CMC|ZSpeed CSC|Z1 Oil cooler|Motordyne Turbo ShockWave)))|Torqen Coilovers|Stanceparts AirCups|Amuse bodykit|GReddy|AEM|ONEighty|Mishimoto|STILLEN|Eibach|SPL|B&M|Radium|EcuTek|BC Forged RS45

JARblue

Very nice work. Excellent detail

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scope22

Have you researched other options for seat brackets? i want the seat to be as low as possible, so i was thinking about side mounted seat brackets?

V1H

The seats sit very low already and the Planted bracket is just a couple cm high. Any lower and there might not be room for the harnesses underneath


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501 BHP, 590 Nm (422 rwhp) AAM TT+I/Plenum|CJM S1 FRS|C/Clutch Stage 2|RJM CMC|ZSpeed CSC|Z1 Oil cooler|Motordyne Turbo ShockWave)))|Torqen Coilovers|Stanceparts AirCups|Amuse bodykit|GReddy|AEM|ONEighty|Mishimoto|STILLEN|Eibach|SPL|B&M|Radium|EcuTek|BC Forged RS45

MR.NYC.370Z

Thanks for the EXCELLENT detail!! I am planning on upgrading my seats next. This will definitely help in that endeavor.

Csharpminor

Awesome! This will help immensely! Btw did you get a chance to take a pic of the switch installed?

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BettyZ

Those seats are beautiful well done!!

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'14 MB Nismo | Boost Lab 6870 1.32 AR 553 HP / 471 ft.-lbs.
Betty Mods

Elusiv3

Does this method with a 15Ω resistor mounted to the occupancy mat work flawlessly and not show the AIRBAG icon?

mikeg32494

Im looking into swapping my seats with new. For some reason the pictures are not showing up, is there any way you could upload them again? Just want to make sure i get the wiring done correctly. Thanks in advance!