No awd!!!
 

Ive been chasing my awd issues for months so far.I have a 2004 xc70 and so far I've had the Dem returned,haldex filter and oil changed,changed haldex pump,new angle gear ,new pressure sensor and refurbed Bcm .Ive got bcm-0095 no comms and Dem-0002 ,000b presure sensor fault which is shutting down the awd.
Any advice would be appreciated.

Stuart

So you have drive from the front wheels to the haldex unit down the propshaft,

The connector to the haldex unit only has 4 wires to it,

12v power,
earth,
Can high (2.8v ish) and low (2.3v ish)

Hi rooster.Ive never checked the actual output but the rear fuse is ok.Im kind of thinking its brought about by the lack of comms on the network at the Cem via the Bcm. There is a permanent fault on no comms with the Bcm .

Need to start with basics then,

First lay under car and make sure propshaft doesn't spin free,

Then you need to get a multimeter to check supplies to DEM connector

Ok,ill have a play tomorrow night weather permitting.Ive not long had a new transfer box fitted after the second sleeve replacement failed causing too much damage but ill check it anway.Its just such an over complicated weak design and not something id expect from Volvo.

Ok I had a fault I the Rem unit that I cleared and took no note of as I thought it was unrelated but now I can clear the bcm fault and Dem faults and get awd!! It will work for 30mins or so then shut down showing Dem-000b pressure sensor.The oil that I removed when doing the work on it the other week was sludgey and grey.Could it need another flush after changing the oil and filter in the AOC? Or is it just a my Dem having a wobbly( was rebuilt by bba reman last year but I've not been impressed with work ive had done in the past) Can anyone recommend a place to look at it?

If its putting pressure faults in its either the pump thats blocked or a faulty sensor,

I know there was an issue with sensors on 05on cars and some even had a recall on them to change them from 40 bar to 80bar i think it was, but yours has had one,

It has Rooster (new from Volvo) and a pump! Can the haldex be overfilled?

AWD Woes
 

Yes it can. I had issues with my AWD R with lack of AWD. I sent my DEM to BBA too...they said it was ok. Spent several months chasing my tail then remembered about help from Lucas at Volvo diagnostics London. Sent him my "working DEM" and he told me it was faulty, but he could not fix it as it was a "unique" issue. Sent me a refurbed unit and the DEM0005 DTC disappeared and AWD returned.
Anyhow in my research, I found an article that said the haldex should be filled to the level then 100ml removed as over filling had proved a problem in some cases ( I love google :) )
I discovered that there is not really a lot to go wrong in the AWD system.
Most issues revolve around the pump not working ( you can check it by removing the electrical connector and directly wiring 12V to it.. You WILL hear it run (or not)
The pressure switch in the DEM unit - could not find a test for that but VIDA/DICE is capable of showing live DATA - including pressure so that lets you know if its working.
The DEM controller suffers from water ingress which causes issues which in my case I believe BBA did not find.
There is a test with an ohm meter that can be done on the canbus connectors to the DEM but I can't find it at present.

The haldex oil ... I have flushed my oil 10 times (at least - I con't get me filter off) so as I had time I flushed the oil - I would get lots of sediment settling out of the oil after standing in glass jars overnight.. so much so that I'm surprised there is still clutch material on the plates in the haldex!! Check yours out. Some reports the oil is reasonably clean - mine was 100% yukky.

Cheers

Bob


Good luck

Cheers

Bob

Hi again Bob.My pumps been changed so don't think its that.The codes I get are only dem-000b oil pressure and bcm -0095 loss of coms to Dem.From the fault flow charts it point to the Dem so I think ill let Lukas look at it this time as I don't trust bba.