Hello Everyone

I know there are numerous threads like this one but my s40's AWD problem is bit weird so I figured I would open one.

So here is my problem, rear wheels on 2006 S40 t5 AWD won't engage, now thing is, when I start the car during morning when car is cold, AWD works fine but after 5-10 minutes of drive, rear wheels stop engaging, we got bit of snow in Michigan yesterday and it was almost impossible to drive the car with All season tires on.

I took the car to the Volvo dealer today and they said whole read diff is kaput. now, I would agree with it, if there was some kind of noise coming from diff or if AWD didn't work at all, but I don't hear anything from rear diff and as I said it works for a while, I figured if diff was gone it wouldn't work at all and it would sure as hell make at least some kind of noise right?

So I just wanted to get the second opinion, can it be DEM, or something else?

Thanks

 

Welcome to the Forum!

1. Never trust the dealer. They are trying to sell you parts and service. Find an independent Volvo mechanic if possible.

2. So it only works when cold? I would suspect something is overheating like the pump. Check out YouTube for some videos on changing the fluid and filter on the Haldex unit.

 

More information???? Your right about the final drive unit, they very rarely have issues, when they do they usually let you know. Many times your local rang rover place knows someone who can rebuild the final drive unit. BUT the Haldex unit is a different animal. You should have all kinds of messages on your DIM????? The electronics which control everything like to send out lots of messages, they are in fact very reliable at doing this. I would like to know how you know the rear drive assembly isn't working? As an example they only kick in when needed??? If you push it and do powerslides up hills in the snow for example you should also be getting the yellow triangle slide indicator , to the right illuminating? As an example. The other thing about snow is all season tires suck, do yourself a big favor and get dedicated winter tires, I would recommend studded nokian's, they make a huge difference in safety!!!! The dealerships don't discriminate between the Haldex and the final drive, they just replace the whole thing, very expensive,.... The haldex fluid should be replaced at 70K and every 70K, and again the dealer's don't do this and Volvo can go ****e, their idea of life time fluids is 5 years BTW, NO SUCH THING AS A LIFE TIME FLUID, STUPID TO EVEN SUGGEST THAT!!!

Anyways good luck separating the coupling to change the haldex filter, don't kill it, they are expensive to replace. Someone will need a suction pump to replace the fluid, if you want to try changing the fluid if the haldex valve has seized or gummed up without changing the filter, THAT IS SOMETHING TO TRY FIRST. THE haldex connector which is in a vulnerable spot can be easily separated or damaged. As well as the haldex control module can be faulty, BUT it throws lots of messages. Their are 2 modules both in ****ty locations BTW! Be aware the final drive lube is just behind the haldex oil fill plugs, DID SOMEONE CONFUSE THESE 2 PLUGS AND YOU COULD HAVE LUBE IN THE OIL???

Changing out the modules should be the first step.

Good luck, everything is rebuild able, BTW but NOT by the dealer. The DEM on the unit is rebuild able as well, but everyone recommends changing the fluid and ultimately the filter, in which case separating the coupling, and or a new coupling would be required, and that's another discussion about how to sepeerate THAT coupling.

Search the internet for DEM rebuilding

 

Thanks guys

I'm planning to change the fluid and the filter first, see how it works out, if it doesn't help then I'm thinking to buy used DEM and try it, is it good idea? or should I rebuild/buy new one.

There are no codes or warning on display, just that TC triangle when uphill on wet surface or on snow.

I put winter tires on this morning and car drives much better, even though I could go without awd with winter tires on, it still bothers me that something's wrong with the car

 

The yellow triangle illuminates when the wheels slip , this is normal and is trying to tell you that your in snow or acceleration to fast or you have bald tires and there slipping, etc.. is that all that is going on? If the DEM module is faulty it throws all kinds of messages. It is always a good idea to suck out the haldex fluid and change it regularly. Changing the filter, you have been warned that that coupling in front of the filter is a difficult job. Not impossible, but difficult. The filter cover is directly behind the coupling , the coupling needs to be pulled apart with a slide hammer like tool,..... you hit the coupling with a hammer the wrong way and it breaks the cv cover inside the coupling, you will then need a rebuilt shaft and or a new coupling. This is why the dealers almost NEVER mess with that coupling on the drive shaft. That coupling is notorious. Personally I take new Volvos , disassemble the coupling cup holder and coat everything with rusfre and or some kind of wax and or grease to make sure it doesn't rust up. Why Volvo makes this coupling so difficult to get to is insane, just a small tweak to the design and it would be so easy to work on,....

If it's actually the DEM, and I'm at a loss how the stealer-ship has arrived at a total failure, not clear about that, again the DEM is very reliable as to letting the 5 computers in your vehicle know that's it has failed, if the DEM has failed it should be rebuilt. You can of course replace one DEM with another to see what happens, You also can disconnect the wires from your exsisting DEM and enjoy the messages which take about 5 seconds to appear on the DIM. If the messages don't appear when you disconnect the harness, well you got me on that one.

xmodex seems to do a great job on rebuilt DEM's, they clean up nice from that guy in CAN. But again I'm not sure you have a haldex issue. Or how the dealer can justify the whole unit is bad? And again sucking out the fluid, it's only about 650 ml of pricy mineral oil, is always a good idea for ALL units at 70K , again I don't believe in lifetime fluids, and the dealer don't have any way of sucking out the fluids for maintenance anyways,....

let us know

BTW the module rebuilt is pricy and if in fact the DEM is defective yes I would be inclined you go salvage yard shopping. Here is one vendor of rebuilt DEM's there are more than this place to go btw: https://xemodex.com/us/product/differential-electronic-module-for-volvo-vo-1040-86001749-10-20/

As an example I just purchased a whole rear end , including the subframe from a salvage yard from a wrecked 2008 S60 AWD for 125 bucks I remove everything, just saying.