New problem - my car's a possum

[johnjapan]

Since Friday my 2006 Subaru Legacy has been becoming almost completely electrically dead, before eventually starting working again.

 

It started with my dashcam and FM transmitter (both connected to the 12v cigarette lighter socket via a USB adapter) switching off while I was driving. I pulled over to check, and when I tried to switch the car on again nothing happened.

.

 

Fast forward to today, I've replaced the battery, and learned a little more about the problem:

- It doesn't seem to have anything to do with what's plugged into the 12v socket - I've removed its fuse. This didn't seem likely anyway since the circuit is only live if the engine's on.

- It doesn't seem to be a ground fault - I've checked the voltage between the engine body and exposed metal on the car. It's 0 volts.

- Things that don't work: remote locking, central locking (via switch inside), interior lights, instrument panel doesn't turn on when the key is moved to the on position or the door is open, door chime.

- Things that do work: hazard/warning lights (and corresponding indicator lights on the instrument panel), parking lights, horn, driver seat motor.

- It's not a low battery as it when it eventually recovers, it starts by itself. Also, jump starting doesn't make a difference when this happens.

 

Battery terminals are tight, battery is new, alternator was checked by a shop and it's OK.

 

Is this likely to be the main relay, or something else? If the relay, then am I correct in thinking it's behind the glovebox?

 

Thanks!

Edited November 20, 2019 by johnjapan

[johnjapan]

OK, so it seems like the 120a main fuse has blown. So I'll get that replaced, though now my thoughts are onto why it has blown.

[Max Capacity]

Main fuse, so where does it get it's incoming power from ?

 

here's the service manual.

 

http://people.csail.mit.edu/ilh/vacation/

[johnjapan]

here's the service manual.

 

Thank you so much! That's super helpful. So far I've only had wiring diagrams (which is all I need in this case) but this has so much more.

 

Before this issue presented I'd been having issues with the secondary air system (I'm actually booked in with Subaru to get it fixed), which seems to run directly off the circuit from the main fuse (MB-33, MB-34). I have an inkling that these two problems are related. I'll have a look down this route and see where it takes me.

 

Thanks again!