Hey guys! So my gf has a 2009 R56 Base N12, but it has the same JBE as a lot (not all) of other R56’s.

And you guessed it, it’s the one that’s prone to the fuel pump relay failing. Or, more specifically, they seem to run so hot that they break the solder joints on the circuit board over time. And you can actually just desolder and add new solder sometimes and fix the issue. But I’m not the type to go that deep into a job and not fully replace an item that may or may not fail again in the future. If I’m in there and it’s possible, or likely, to fail again, I’ll just replace it.

Also, I know that there are legit places that will replace or fix this for you for $200ish. But again, in my opinion this is a clear design flaw. They get so hot that they heat score the circuit boards where they rest. Not to mention that you have to remove the JBE, open the plastic case, desolder 2 boards from each other or cut them apart and resolder after, just to get to the relay. Then desolder the 8 pins. And oh yeah, the only place that I can find the factory relay from is China, then wait a month ish to get it.

ALL of that sounds completely horrible! So instead, I used my 22 years of submarine electronics training and experience and found wiring and pin out diagrams instead to try to figure out how to fix this easier and make it better, more reliable, and more accessible. Not to mention that it HAS to be helpful for the life of the rest of that circuit board to remove that heat source altogether if possible.

I figured that someone else HAD to have already reverse engineered this thing and done the same. But if so I couldn’t find it on here or the internet in any other place. There is one thread from about a year ago where a guy ALMOST cracked the code and got it right, but not quite.

So now that I gave all of that background and story, my next post will be what my plan is. The relay that I ordered won’t be here until tomorrow. So I’ll post pics and results when I get and install it. But I’m pretty confident with my idea.

 

So we really only need to know a few things to make this work. Specifically, only 4 wires.

1. Like all automotive relays, it needs a constant 12v.
2. Key on power. Since you clearly only want your fuel running at that point.
3. A DME trigger, as that also is a trigger for the K96 relay to activate. In this case, that trigger isn’t a power source, it actually is a ground. So the circuit is grounded by that DME wire and doesn’t receive actual power.
4. The wire that actually feeds power to the fuel pump in my case, or LPFP for you guys with an S.

Now, because we’re moving this off of the circuit board and it applicable fuse panel, we need a fuse as well so that wires don’t melt and electrical fires don’t start in the event of a casualty or short. In my case, the factory fuel pump fuse for N12’s is a 20 amp.

So I ordered a 4 wire fused relay. They are super cheap on Amazon and I ordered mine last night and it will be here tomorrow. Mine comes with a 30 amp fuse, but again, I’ll be dropping it down to a 20 amp.

Access to all of the wires needed are VERY easily accessible right at the DME area once you remove the passenger side kick panel covering. And that only requires a T-50 torx bit for the lower seat belt bolt and then it snaps right out.

So here are the 2 connectors that you need to disconnect to get the fuel pump wire and DME grounding wire. Each connector has one of the 2 required wires.

The black plug/connector has the DME ground wire. It’s purple/green. Which for non electrical guys, that means the wire itself is purple, and it has a green stripe on it.

The white plug has the white/blue wire that actually goes to the fuel pump itself providing power.

12v constant comes from the pink/green wire which needs to be spliced.

12v key on comes from the larger gauge pink/blue wire and also needs to be spliced.

The 12v power wire as well as the 12v only with key on are both also easily accessible in a wire loom near the JBE closest to the rear of the car. However, these 2 wires perform other functions as well, so they need to be spliced, as opposed to cut and wired directly to the new fused relay, like the DME and fuel pump wires.

DISCONNECT YOUR BATTERY BEFORE CUTTING OR SPLICING ANY WIRES!!!! Start with the constant 12v power wire otherwise, and it will remind you to do so and it will be a self correcting problem! Lol

Before you cut the wires from the plug, it’s good practice to leave enough wire on the back of the plug in case, for whatever reason, you wanted to easily be able to wire it back the factory way. And if you cut too closely there won’t be enough slack left to do that.

Relay Wiring.

Pin 30, usually the red or sometimes yellow wire on the relay harness depending on the brand of relay you order, connects to the 12v constant pink/green wire splice.

Pin 86, the white relay wire, connects to the 12v key on pink/blue wire splice.

Pin 87, the blue relay wire, connects to the fuel pump white blue wire that you cut from the white connector plug.

Pin 85, the black relay wire, connects to the DME wire that you cut from the black connector plug.

That’s it. Then make sure that you have the appropriately sized fuse and tuck it away next to the DME when you put your interior panel back on.

The whole JBE.

The black connector with the DME purple/green wire.

The white connector with the fuel pump white/blue wire.

A general 4 plug relay harness wiring layout.

Where the white and black plug/connectors are located.

The 12v constant pink/green wire and the 12v key/ignition on pink/blue wires that need to be spliced.