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

=== Assistant: Thank you — these additional photos actually seal the diagnosis. ===
Thank you — these additional photos actually seal the diagnosis. I’m going to break this into three clean sections, so you know exactly what you’re looking at, what must be replaced or corrected, and how to proceed by the book, without guessing.

I’ll be direct, because this is high-current, fire-risk territory.

==== ### ====

Across multiple angles, we now clearly see:
* Heat discoloration around the aluminum fuse plate
* Darkened / oxidized stud surfaces
* Deformed plastic at the base of at least one high-current output
* Evidence of localized overheating, not just age

That means internal resistance exists, even if continuity still “checks good.”

: 

That perfectly matches your symptom:
fast crank + no start + low system voltage at ignition ON

===== Several photos clearly show: =====
* Thin blue, green, white, and red wires
* Electrical tape splices
* Aftermarket connectors routed over and across A46 studs

These do not belong on the rear distribution panel.

This is critical:

: 

Any added wiring here:
* Increases resistance
* Creates heat
* Causes voltage sag under load
* Can prevent the DME from waking up fully

These wires must be removed or rerouted correctly — not transferred blindly to the new unit.

===== Your images show: =====
* Rust staining under the battery
* Damp residue in the tray area
* Corrosion creep up the fasteners

This explains:
* Why the distribution box overheated
* Why oxidation is present
* Why voltage drops even with a charged battery

Water + current = slow electrical death.

==== ### ====
* Rear Power Distribution Box (A46) — no exceptions (fusible links are internal and non-serviceable)

===== - Any ring terminal that shows: - Blueing - Pitting - Heat shadow =====
* All non-OEM wiring attached to A46
* Battery tray corrosion (clean & neutralize)
* Any loose or stacked cable connections

If you don’t do these, a new A46 will fail again.

==== This is the exact sequence you should follow on your car. ====

===== - 10 mm socket (terminals) =====
* 13 mm socket (A46 studs)
* Torque wrench
* Marker / tape
* Contact cleaner
* Wire brush or Scotch-Brite

==== 1. Key OUT ====
# Trunk open
# Let car sit 5–10 minutes (modules sleep)

==== 1. Negative cable OFF first - Do not stress the IBS ====
# Open BST cover
# Positive cable OFF

==== 1. Remove hold-down ====
# Disconnect vent tube
# Lift battery out

==== Before touching A46 studs: ====
* Take photos
* Label each OEM cable
* Label every thin aftermarket wire as “NON-OEM”

⚠️ These aftermarket wires do NOT get reinstalled onto A46 unless you can identify them 100%.

==== 1. Using 13 mm socket: - Remove one stud nut - Remove one cable ====
# Set cables aside in order
# Do not stack loose cables

==== Any terminal that shows: ====
* Burnt insulation
* Blackened copper
* Warping

➡️ Replace or repair it now

Do NOT reuse damaged terminals on a new distribution box.

==== 1. Place new unit in position ====
# Transfer OEM cables only, one at a time
# Torque stud nuts to 15 Nm (11 ft-lb)

⚠️ Do not overtighten — aluminum studs strip easily

==== Those thin wires must be: ====
* Removed entirely or
* Re-routed to: - A fused accessory block - Or a proper distribution point elsewhere

They do not belong on A46. Period.

If you want, I can help you trace them safely.

==== 1. Battery in ====
# Vent tube connected
# Hold-down installed

==== 1. Positive FIRST ====
# Torque clamp: - M6 → 5 Nm (44 in-lb)
# Negative LAST
# IBS seated, not twisted

==== Multimeter checks: ====
* Battery posts: 12.5–12.8 V
* Jump post: within 0.1 V of battery

If not — stop and recheck connections.

==== - Clean battery tray ====
* Neutralize corrosion
* If battery type or rating changed → register battery in ISTA

==== Based on all images: ====
* Your A46 was failing electrically before it failed visually
* The non-OEM wiring likely accelerated the damage
* This setup can absolutely cause fast crank / no start
* Replacing A46 correctly is the right move — but only if the wiring is corrected

===== If you want, I can: =====
* Identify each A46 stud and its function
* Help you trace every non-OEM wire
* Walk you through ISTA checks after install
* Verify DME power integrity step-by-step

You’re doing this the right way.
Just don’t rush the wiring cleanup — that’s where these cars punish shortcuts.