P2 2001 V70 T5 Sudden Massive Electrical Failure

[Brickbat]

I sold it.

As I was going through this, I was also keeping an eye out for a replacement vehicle, and came across a 2006 XC70 with under 100k, and super-well maintained. So I bought it. The buyer of the car in this thread was made aware of the issue - I even printed out a bit of this thread for him.

But here's the twist.

A few days after I sold the 2001, I was putting a trailer hitch on my 'new' XC70, and while hooking up the trailer wiring I came across what I think might have been the root cause of the problem in the 2001. As I've noted in this thread, the problem 'felt' like it was caused by an intermittent power or ground wire/fuse somewhere. But I ran out of places to look, having checked the main fuses (back by the battery), the fuses and relays in the REM, CEM and all fuses and connections in the under-hood fusebox, along with every ground connection I could find.

Any guesses what I found ?

[RickHaleParker]

I'll guess. You found a feedthrough hole with a insulating ring. If the insulating ring deteriorates, sheet metal can cut through the insulation on the power cable.

[Brickbat]

So what I saw in the 2006 were these pair of BFC's (Big Fat Connectors). Each had a pair of red 10-ish gauge wire. I think they bring power from the fuse panel beside the battery up to the the CEM, drivers door fuse panel, and under-hood fuse panels. The pic shows their location in my 2006, right under the REM.

Now, I don't know if these are in the 2001 V70, but if they are, they'd be the prime suspect. I'd want to unplug, inspect, clean and reconnect them. Seems to me that an intermittent connection here could well be the cause of what I was seeing.

All's well that ends well - the 2006 XC70 is a super nice replacement for the 2001...

[precopster]

Usually no. Canbus is a protocol not a physical item you can touch. There are many test points to use.

This year I repaired an XC90 2007 with suspected Canbus issue. Door locks, climate control and another circuit I can't remember were down however were down permanently unlike yours.

It ended up being a corroded main power cable where it meets a connector in the left lower corner near the REM. There were just a few strands of copper still carrying voltage to the above modules. Testing with a meter showed voltage at all fuses however using a load (21W test lamp) showed otherwise.

IT PAYS TO READ PREVIOUS POSTS Good luck with the 2006

[Brickbat]

Yes - I recall that, and asking how it got corroded, and ignoring it, because I saw no signs of corrosion anywhere that I looked. And it was a 2007 XC90, so I didn't know whether it even applied to my P2. Also I assumed (wrongly) that you were referring to the connections at the main fuse panel near the battery, which I had already checked.

Anyway, this probably cost me $500 in resale value, but I got a nice deal on the 2006, so not complaining.

[mrbrian200]

I may have mentioned those too, but I might be thinking of another thread. Yes one of those two big plugs are the two red wires that go to and power the CEM and anything that is controlled by relays on the CEM, except either the high or low beams where +B power originates from the underhood fuse panel/main battery cable and loops through a relay on the cem then back out to the headlamps. Yes I'm fairly certain an '01 has those in a nearly identical power distribution layout to my '06. The second connector/set of wires feeds a group of fuses on the interior fuse panel for most of the interior electronics/power seats etc that don't get their main power through the CEM.

[abscate]

So what I saw in the 2006 were these pair of BFC's (Big Fat Connectors). Each had a pair of red 10-ish gauge wire. I think they bring power from the fuse panel beside the battery up to the the CEM, drivers door fuse panel, and under-hood fuse panels. The pic shows their location in my 2006, right under the REM.2018-02-19 22.22.45.jpg

Now, I don't know if these are in the 2001 V70, but if they are, they'd be the prime suspect. I'd want to unplug, inspect, clean and reconnect them. Seems to me that an intermittent connection here could well be the cause of what I was seeing.

All's well that ends well - the 2006 XC70 is a super nice replacement for the 2001...

Thanks for F/Up

Mental note to go check my BFC for corrosion on my P2

[mrbrian200]

The problem with these BFCs, which applies to most all of the interior electrical system which isn't protected against moisture is potentially if you've ever had water intrusion that results in heavy condensation in the interior or trunk areas over an extended period where the car never really dries out. If all your door/trunk seals and such are good these cars are very tight and can trap moisture in the interior for a quite a while. Especially in the spring/fall when temperatures are lower and (in most areas here in the US) atmospheric RH tends to be high.
This is one of the few cars I've ever owned where it can be at or below freezing outside but the interior will warm up nice and toasty warm in these genuinely cold conditions if the sun is out.

If you ever do something like accidentally leave it parked with window(s) rolled down during a heavy rain, or shampoo and rinse the carpets leaving them all moist and soggy.. you never, ever want to close the car up until you're certain it's dried out thoroughly. If you come out in the morning and notice any sort of condensation on interior side of the windscreen it wasn't dry yet and you're really asking for trouble.

[precopster]

The 2007 XC90 I repaired had a history of a small rear fender bender where the rear left tail light was replaced. As is usual with panel shops they strip them down for quote and inspection, then leave them sitting in the yard until the parts/insurance approval arrive or perhaps they had already done the bodywork and were waiting for the rear light to arrive; which left a gaping hole in the rear left side.

It obviously rained or was carelessly washed while it was waiting. The corrosion would have been very slight at the beginning and it took about 2 years to eat through the copper one strand at at a time. There were 3 or 4 corroded strands still carrying voltage but could not carry enough current to power up the modules. I stripped them back and joined the wires together with heavy red cable then soldered them all together. Then sealed them with tape.