P2 2001 V70 T5 Sudden Massive Electrical Failure

[Brickbat]

I disagree that it's the alternator. Even if the alternator died totally, I don't see how that'd cause a sudden electrical power loss, since the battery would have sourced power to all loads in the car for quite some time. I've spent a LOT of time studying the wiring diagrams, so if you can explain how it's the alternator in greater detail, I'm all ears. I have NOT seen the 'power system failure' that popped up in the DIM when the first alternator quit, nor has there ever been an alternator (or whatever it's called) idiot light.

Further, early in my diagnosis phase, I had the failure occur while I had a data logger on the battery, monitoring the voltage. I couldn't see even the tiniest hiccup in the battery voltage when the failure occurred.

[RickHaleParker]

Brickbat I think I spotted one place you have not looked, that is common to all things your having problems with but, not common to the starting system. The main buss on the main fuse box.

[Brickbat]

I carefully checked all connections and fuses in all 4 fuse locations (under hood-both layers, drivers side, REM, and main fuses near battery). Are there more fuses in this car that I haven't found?

So, I'm not sure what you mean by 'main bus' but I've been thinking along the lines you are and have checked every power connection in and around every fuse location I found...

[RickHaleParker]

Buss or Bus are informal names for Busbar.

Main Busbar, In the main fuse box one side of all the fuses are connected together on a bar, this is the Main Busbar. If you lose power to that, you lose power to just about everything. The starting system is not on that Busbar.

Did you look at the backside of the fuse boxes. Sometimes the fuse box goes bad. It does not happen often but it is not unheard of.

Four fuse boxes: Main and engine in engine compartment. Cab at the end of the dash. Rear in the cargo area.

[Brickbat]

If there's really two fuseboxes in the engine compartment, that totals 5, because there's also the cluster of 50A fuses back by the battery, which I have also checked. Maybe you're referring to an S70 or C70? (The V70 battery is in the back cargo area.)

On my 2001 V70, I've not found two fuseboxes in the engine compartment. There's one on the drivers' side, near the brake hydraulics. It has two 'levels' as I noted (i.e you have to unbolt the upper half to access the underside), and I've inspected it carefully, revealing nothing unusual. Can you tell me where the other engine compartment fuse box is?

[abscate]

I think you lose an engine compartment fuse box on the P2 transition in 2001, the P80s have two.

[93SCMax]

Can you tell me where the other engine compartment fuse box is?

There are three fuse boxes in a 2001 V70 T5 (per owners manual, and visual confirmation of my car):
1) Engine compartment (drivers side)
2) Passenger compartment (drivers side)
3) Cargo area (drivers side)

You have them covered!

[RickHaleParker]

If there's really two fuseboxes in the engine compartment, that totals 5, because there's also the cluster of 50A fuses back by the battery,

That right the Main Fuse Panel moved with the battery on the V70. That bank of 50A fuses, in the cargo compartment, is the Main Fuse Panel. That is the one to inspect on the backside.

• 1. Main fuse, cargo compartment.
  2. Integrated relay/fuse box cargo compartment.
  3. Fusebox, passenger compartment.
  4. Integrated relay/fuse box, engine compartment.

[Brickbat]

Yep - as stated about a half dozen times - all fuseboxes inspected thoroughly - all good...

[RickHaleParker]

Next I would would go through the wiring from the positive side of the battery to the four fuse box Busbars and the Alternator looking for damage that would case a short to ground or an open. Right near the battery would be a good place to start, it might be disconnecting the battery is moving a cable causing an open to close or a short to open.