Car is completely dead after installation of new battery

Seaneezy

Corporal
Mar 12, 2018
130
34
0
Ride
e90 LCI 335i
Had issues with my old battery losing charge so I got a replacement AGM from PepBoys to replace it. I've done this before and it was fine. On the latest replacement, when going to register the new battery I realize I have no power whatsoever to the car. I insert the key fob and there are no lights on the dashboard, no pump priming sound or anything. I double-checked the connections on the battery and the 13mm up front and no dice. I looked online to see this issue mainly being related to a faulty B+ cable behind the fuse box, however it seemed that a correct diagnosis was by shaking the fuse box or wiggling the 12V cable behind the fuse box. I shook the box and wiggled the cable after removing the glove box and lower cover and I still had no power whatsoever.

Before I go about removing the fuse box to check the connection (I would have to tow the car at that point as I don't have the crimping expertise to be confident about replacing the cable), are there any other potential causes for this issue I can check first?

So far I have hooked a battery jumper to the engine bay leads and used a backup key fob to check if the current one was dead. I zip-tied the positive and negative battery terminal cables away from the battery to help installation, could I have bent those cables doing that?

Thanks!
 

NoQuarter

Major
Nov 24, 2017
1,605
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Indiana, USA
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Z4 35is, 535xi, X5 35i
There is fusible link on the positive battery cable where it all mounts to the battery in the plastic case/tray.

It is what gets disconnected in the event of an accident.
 
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Torgus

Major
Nov 6, 2016
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Boston
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ACF 6466 E92 + METH
Get out a multimeter. If you don't know how to use one it is very simple and watch tutorials online. Wiggling shit is a last ditch effort ;)

I would hazard to guess the fusible link may be gone. Which is good as it is designed to protect.
 

Seaneezy

Corporal
Mar 12, 2018
130
34
0
Ride
e90 LCI 335i
There is fusible link on the positive battery cable where it all mounts to the battery in the plastic case/tray.

It is what gets disconnected in the event of an accident.
Where would it be disconnected? I'm assuming it would need a replacement and cannot be "reconnected"?.

At first I thought you were referencing the power distribution block, so I removed the cover and tested the fuses and got continuity for each, even when two of the fuses look completely burnt out (second and third fuses that aren't actively connected), and a small scorch on the terminal inside that block but seems fine outside of that.

To test the fusible link, would I remove that positive battery terminal and test the connections from terminal to terminal? (using https://www.fcpeuro.com/products/bmw-battery-cable-plus-pole-sbk-61129217031 as a reference)

Thanks again
 

Seaneezy

Corporal
Mar 12, 2018
130
34
0
Ride
e90 LCI 335i
Yes. This is exactly what I would do
Removed the cable and got resistance between both ends/terminals of the cable. While the battery was out I also checked the B+ cable since the terminal was right under the positive cable, and I have continuity on that cable as well before dropping the terminal nut into the abyss underneath the battery panel.

Before I remove the fuse box, is there any test I can do for the negative cable as well? My only other suspicion for the components in the trunk is that I kinked that cable.

Thanks for the help
 

Seaneezy

Corporal
Mar 12, 2018
130
34
0
Ride
e90 LCI 335i
Late bump, recently returned from a business trip and found the time to continue working on the car. I removed the fuse box and found the B+ cable that looked fine, no burn marks or signs of fusing to the junction box like the recall specifies. I am once again confused on why my car has no power at all.

I have a suspicion of water damage to the DME, but from my understanding that would just mean the car couldn't crank but power to accessory or anything else would be fine.

Anyone have any idea/recollection of anything like this happening before I push it onto the street to get towed?
 

Seaneezy

Corporal
Mar 12, 2018
130
34
0
Ride
e90 LCI 335i
Reinstalled fuse connectors + JBE and left the fuse box hanging, reinstalled the battery and I suddenly have power. Shaking the fuse box/wiggling the B+ cable doesn't seem to have any effect on power supply to the car, so I actually have no idea what happened over 2 months that allows the car to run now. Registered the new battery with carly then heard what I think is either an audio/radio pop or a shorted wire behind idrive, but that's a different issue.