AWD Transmission: xc90 d5 2005 05 loosing traction

[Multiplex]

Originally Posted by davos

Hi all, also just discovered that my AWD is a front only drive 4x4? have had the vehicle on the ramp over christmas and if i turn the prop the front wheels only turn, so this indicates that the splines / gears are ok. Problem is is the sensor or the pump at fault? no fault codes present no warning on the dash! that`s pretty poor diagnostics from volvo not what i expected from a prestige vehicle. Can anyone help in detecting which is at fault.

If the prop is turning the wheels and visa versa then as mentioned earlier in this thread the sleeve, splines and angle drive are ok. You will not get the rear wheels to turn when turning the prop by hand.

If there ar no DTCs logged for the haldex then i would suspect the system is operating ok. Some haldex units had faulty pressure sensors that would prevent the drive transmitting to the rear however if this was faulty there would be a DTC.

With the vehicle on the ramp and all 4 wheels free from the ground, turn off the DSTC system, start the engine and select 1st gear or drive.

All 4 wheels should rotate.

[davos]

Thanks for your input on my problem with my AWD system, i did not try turning the traction control off and engaging gear whilst on the ramps, but have turned it on and off while on the slippy stuff but their was no difference to the drive of the rear wheels. Surely this would show if power was transmitting to the rear wheels?. So back to my original question of pin pointing which is to blame. Doe`s the pump not log a management fault code? it`s the difference of around £200 between the cost of the pump and switch, you cannot just guess at which it`s going tobe, never been very lucky at flicking a coin. Help tech guy`s.

[Davidhol]

Does the T6 use the samw AWD system? Mine has just become a two wheel drive and I'd like to know whether all these AWD posts for the other models are applicable to my T6

[Clan]

No the T6 has a completely different arrangement involving a chain ...

[Multiplex]

Originally Posted by davos

Thanks for your input on my problem with my AWD system, i did not try turning the traction control off and engaging gear whilst on the ramps, but have turned it on and off while on the slippy stuff but their was no difference to the drive of the rear wheels. Surely this would show if power was transmitting to the rear wheels?. So back to my original question of pin pointing which is to blame. Doe`s the pump not log a management fault code? it`s the difference of around £200 between the cost of the pump and switch, you cannot just guess at which it`s going tobe, never been very lucky at flicking a coin. Help tech guy`s.

If you can not get your vehicle back on a ramp then you could try marking the prop position/centre support bearing with chalk. Then drive the vehicle a short distance (only needs to be a few feet of so). Re-check the position of the mark - if it has moved then the sleve/angle drive is ok as the prop is turning and eliminates these components. If the prop has not moved then the problem is with the angle drive/sleeve. The only way forward then is to remove the angle drive unit and inspect the splines. It may just need a sleve or it may require both if there is wear on the angle drive splines.

If the mark has moved then you need to be looking at the haldex unit (differential module or DEM in Volvo terms). One thing you could try is holding down the "read" button on the end of the indicator stalk and pressing the rear fog lamp button twice. This changes the infomation display on the dashboard and will tell you what modules have a DTC logged. The one you want to look for is the DEM. Dont be too alarmed if other modules have DTCs in them - the Volvo diagnostic software is quite sensitive and a lot of "ghost codes" will be in there!

The DEM status will either be -

• DEM DTC Logged (the DEM has detected a problem and has stored a fault code)
• DEM Checking (no DTC logged however DEM has not completed its diagnostic checks in the current operating cycle)
• DEM No DTC - The DEM is fault free

If the DEM is showing a DTC then it will need to go onto a diagnostic machine to find out what the DTC is. Also if there is a DTC in the DEM then it will shut down/prevent the transmission of power to the reaw wheels.

With all the snow thats about at the moment i am seeing a few AWD Volvo's that the owners have noticed are only two wheel drive!

[bobdabuilda]

Originally Posted by Multiplex

One thing you could try is holding down the "read" button on the end of the indicator stalk and pressing the rear fog lamp button twice. This changes the infomation display on the dashboard and will tell you what modules have a DTC logged. The one you want to look for is the DEM. Dont be too alarmed if other modules have DTCs in them - the Volvo diagnostic software is quite sensitive and a lot of "ghost codes" will be in there!

The DEM status will either be -

• DEM DTC Logged (the DEM has detected a problem and has stored a fault code)
• DEM Checking (no DTC logged however DEM has not completed its diagnostic checks in the current operating cycle)
• DEM No DTC - The DEM is fault free

If the DEM is showing a DTC then it will need to go onto a diagnostic machine to find out what the DTC is. Also if there is a DTC in the DEM then it will shut down/prevent the transmission of power to the reaw wheels.

With all the snow thats about at the moment i am seeing a few AWD Volvo's that the owners have noticed are only two wheel drive!

What does 'DEM DTC SET' mean please? That's what's showing up on mine when I do the above. Does that mean mine is 2wd now?

[Clan]

'DEM DTC SET' means there is a fault code stored in the rear differential control module and will need reading to be guided from there ..
If it is DEM 0007 it will be an oil pressure sensor , the dealer will need to read their bulletin to determine which sensor is needed , there are two types . Yes with a code stored it will disable rear wheel drive ..

[bobdabuilda]

Thanks Clan- I know I have asked you before but are you anywhere near Cardiff as you have detailed knowledge of the car?

[bobdabuilda]

one other question - with regards to the possible problems of

1. Electronic traction control sensor may have failed.
2. Rear Propshaft spline / sleeve may have stripped.
3. Angle gear may be damaged from prop failure or even stripped in its own right.

have the new parts supplied by Volvo addressed the early failure problems or is the system fundamentally flawed for good?

[bobdabuilda]

Had the car checked over today and apparently the DEM DTC SETcode indicated an intermittent fault on the awd traction sensor which apparently is a known problem even on 07 models hence they have increased the warranty period for an extra year on this part alone!

There is also an ECM DTC SET code which relates to the fuel pressure sensor which they think wasn't reset from an earlier service but is now back after resetting so looks like that needs doing too. Glad it's still under warranty.

The interesting thing is that the car never showed up this fault on the normal message system -apparently it should have indicated fault on dstc - therefore it's worth checking the special functions indicated above by holding the read button and pressing the rear fog button twice.