Dem communication problems

[Mick82]

The dem is working I think got no anti skid message does the pump run all the time or does it just kick in when it's needed? Traction control kicks in

[LeeT5]

Hi all new to the forum. I have a 2007 xc90 d5 185 bhp with 192000 having a problem with the dem module not communicating with vida just wondering if any body else had the same problem. Also the mechanic said it could be the pump but I've tested the pump when my original module went down and it was fine run 12v to it and it fired up but could a dodgy pump prevent Vida from communicating with it any advise would be gratefully appreciated thanks in advance.
Mick82 is offline

I'm assuming you can communicate with all other modules??

The dem is working I think got no anti skid message does the pump run all the time or does it just kick in when it's needed? Traction control kicks in

Traction control has nothing to do with the DEM. TRACS is controlled by the ABS module and wheel speed sensors.

If the DEM pump is not running, you'll know soon enough if you try to pull away quick in the wet.
The DEM pump runs all the time.

Haldex Gen 4 (which is fitted to your car) has an electronic pump which is constantly running as soon as you switch on the engine. Running a MAX pressure, full time!

Would help more if you could post the fault codes you have?

[Mick82]

I'm assuming you can communicate with all other modules??



Traction control has nothing to do with the DEM. TRACS is controlled by the ABS module and wheel speed sensors.

If the DEM pump is not running, you'll know soon enough if you try to pull away quick in the wet.
The DEM pump runs all the time.

Haldex Gen 4 (which is fitted to your car) has an electronic pump which is constantly running as soon as you switch on the engine. Running a MAX pressure, full time!

Would help more if you could post the fault codes you have?

I haven't got any fault codes it won't communicate

[Mick82]

I haven't got any fault codes it won't communicate

Also when u say it's nothing to do with trac when my original module went down front wheels used to spin up all time in wet but with the new dem it doesn't so surely it's got to have some sort of use within the system.

[LeeT5]

Also when u say it's nothing to do with trac when my original module went down front wheels used to spin up all time in wet but with the new dem it doesn't so surely it's got to have some sort of use within the system.

No. That just means the AWD is working as drive is going to the rear wheels, so no wheel spin.
Wet or dry, my wheels would spin when my DEM failed.