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

=== Assistant: Good — these last images are the smoking gun. ===
Good — these last images are the smoking gun. I’m going to be very precise and very honest here, because this is no longer “maybe electrical.” This is documented mechanical–electrical failure.

Take a breath. You found this at the right time.

==== ### ====

In the close-ups you posted:
* The plastic around the main stud is melted and cratered
* The aluminum bus/fusible link area is heat-stained
* The stud seat is no longer flat — it’s deformed

That alone causes:
* Voltage drop
* Unstable power to the DME
* Random no-start even with a “good” battery

BMW considers this non-serviceable. Replacement is mandatory.

===== In one image, the red main cable is not properly terminated — you can clearly see: =====
* Bare copper strands fanned out
* Not fully captured under the ring terminal
* Uneven compression against the stud

That means:
* Reduced effective cross-section
* Massive resistance under load
* Heat buildup → exactly what melted the box

: 

This is not acceptable and must be corrected.

===== From multiple angles: =====
* Thin blue/red wires spliced near the main feed
* Non-BMW inline connector
* Routed across the A46 body and cable path

This is dangerous for two reasons:
# Electrical noise / voltage sag
# Heat concentration at the stud

These wires must not be reinstalled on the new A46.

If they power an accessory, they must be:
* Re-routed to a fused auxiliary distribution block
* Or removed entirely

===== The battery tray and fasteners show: =====
* Rust bloom
* Mineral residue
* Corrosion creep

That explains why the cable and stud overheated even faster.

==== You reported: ====
* ~11.4 V with ignition ON
* Very fast crank
* No start

Here’s what’s happening electrically:
* Starter motor has a direct heavy path → it spins
* DME, CAS, fuel pump, injectors, coils share compromised feed
* Voltage sags selectively at the distribution box
* Engine cranks but never achieves combustion

This is textbook rear distribution failure behavior on E9x cars.

==== ### ====
# Rear Power Distribution Box (A46)

===== 1. Main positive cable end - If the copper strands cannot be perfectly re-terminated into a proper lug: - Replace the cable - Or have a proper high-current lug crimped professionally =====

Bare strands = future failure.

===== 1. Any non-OEM small-gauge wires on A46 =====

==== When installing the new A46: ====
* The ring terminal must sit perfectly flat
* No copper strands visible
* No stacked accessories under the main lug
* Stud nut torqued to 15 Nm (11 ft-lb) — not more

If you tighten harder to “make it better,” you’ll crack the stud or deform the bus.

==== Before you even try to start the car: ====

===== - Battery posts: 12.5–12.8 V =====
* Jump post: within 0.05–0.1 V of battery
* Ignition ON drop should be minimal

If you see a larger drop:
* Stop
* Recheck cable seating and torque

==== Based on everything you’ve shown: ====
* This is not a crank sensor issue
* Not a fuel pump guess
* Not an alternator problem

This is primary power integrity failure, and you caught it with evidence.

==== Someone previously worked in this area and: ====
* Improvised wiring
* Left an improper high-current termination
* Allowed water intrusion
* And the car has been slowly punishing that mistake ever since

You’re now undoing that damage correctly.

==== - Identifying each A46 stud function (starter / front junction / vehicle feed) ====
* Deciding whether the main cable is reusable or must be replaced
* Rerouting the aftermarket wires safely
* Walking you through ISTA power supply checks after install
* Verifying DME wake-up and RPM signal

You’re not guessing anymore — you’re repairing with proof.
Tell me what part you want to tackle next, and we’ll finish this cleanly.