Editing Openai/6940b2df-db80-8003-b707-4cc5cbedf6d9 (section)

=== Assistant: Perfect. ===
Perfect. These photos tell me exactly what you bought — and the short version is:

👉 Yes, this replacement power distribution box is the correct style and is usable
👉 BUT there are two critical prep steps you must do before bolting it onto the car, or you’ll recreate the same failure.

I’ll walk you through this in a clean, no-nonsense, step-by-step install sequence, tailored to this exact replacement unit and your damaged setup.

==== From your images: ====
* ✅ Correct A46 rear power distribution box for E90
* ✅ Correct fusible link architecture (non-serviceable links)
* ✅ Correct stud layout and orientation
* ✅ Torque marking 15 Nm clearly visible (matches BMW spec)

This is not a cheap universal substitute. It’s the right part.

However…

===== Your close-ups show: =====
* The main stud seat is clean (good)
* The plastic housing is intact (good)
* BUT the stud opening is ovalized by design, which means:

: 

So the success of this repair now depends more on the cable end than the box itself.

==== ### ====

The red cable that goes to this stud must meet all of the following:
* ✔️ Ring terminal is perfectly flat
* ✔️ No cracks
* ✔️ No blueing
* ✔️ NO exposed copper strands
* ✔️ Lug hole is round, not wallowed out

====== 👉 Stop ======
👉 Have the cable end professionally re-terminated or replace the cable

This is not optional. Your old box failed because of this exact issue.

===== Before assembly: =====
* Lightly clean the lug face with Scotch-Brite or fine wire brush
* Clean the stud face
* Do NOT grease or oil the connection

BMW wants metal-to-metal contact, dry.

==== ### ====

You already know this, but for completeness:
* Battery removed
* Vent hose disconnected
* Battery tray exposed

===== - Set the new A46 unit in place =====
* Ensure it sits flat and square
* No wiring trapped underneath

===== This prevents stack errors. =====

====== 1. Largest OEM cable first (flush against the box) ======
# Secondary OEM cable (if applicable)
# Nut

⚠️ No aftermarket wires
⚠️ No thin gauge accessories
⚠️ No stacking three or four lugs

If it didn’t come from BMW, it doesn’t go here.

===== - Torque each stud nut to 15 Nm (11 ft-lb) =====
* Stop. Do not go further.

Over-torque:
* Deforms the aluminum bus
* Cracks the plastic base
* Causes heat rise later

==== 1. Battery in tray ====
# Vent tube connected
# Hold-down secured
# Positive terminal FIRST
# Negative terminal LAST (careful with IBS)

Torque terminal clamps to:
* 5 Nm (44 in-lb) if M6

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