2006 V70D5AWD REM-DEM problems

[ILOVEPV]

I have multiple problems with my car and I am beginning to think that there may be a REM-problem:

1) AWD does not work. I have 12VDC at fuse #23 of REM, but not in the DEM power supply connector under the car. I measured around 5VDC there. Traced the cable and had 5VDC in the connector under the back seat, then traced it to the connector on the back of the REM where it was also 5VDC. Thus, something fishy in the REM since I have read it should be 12VDC all the way. Can something in the REM block the power supply to the DEM or should it always be 12VDC? If yes, would it be possible to supply the DEM directly with 12VDC or am I on thin ice if I do that? FYI, pump runs with direct 12VDC.

2) Suddenly while working with the AWD the heater decided to not start, the fan in the heater just started, and then, it shut off. Having help from a collegue with VIDA I see REM-4A48 Fuel level too low is active, could that be the cause of heater not starting? There is no message about too low fuel level in the DIM, but I don't know if there is on this model?

3) To try to reset the heater faulty starts, I did a suggested reset by breaking the battery power, this was done while I had the back of the car on a hoist for the AWD-problem. When driving the car to work I realized the bi-xenons were pointing straight down. Got suggestion to have car in level and disconnected again, didn't solve the problem. When checking with VIDA REM-8F11 Xenon sensor low signal was active. Think I saw something that the sensor voltage was 0VDC.. Tried to calibrate Xenon with VIDA, but didn't work.(Neither of us knows VIDA well but found a fuction about this)

With all the above I am thinking the REM might be the problem. I have taken it out of the car and disassembled it to see if I have any "burns" on the card, but cant see anything straight off. Anyone that has any idea of things to consider check while having it apart?

[precopster]

Some of these miscommunication faults can be unrelated to any real fault. They are usually a temporary disturbance on the Canbus. If you reset these faults do they return immediately? REMs can fail in only one function so it can be likely it has shut down the Bi-Xenon signal. There should be a Bi-Xenon calibration menu in Vehicle Communication under Activations. Check it out.

Definitely DO NOT separately power the DEM. It won't restore AWD function. Is there a chance water ingress on DEM is pulling 12V low to 5V ? Remove DEM connectors x 2 and re-measure the voltage. If it's still low the REM is your major suspect. Don't discount that water ingress on the DEM board has caused this problem. Open it up and thoroughly clean the DEM board and reseal it well.

If Activation/Calibration doesn't work for the Bi-Xenons you may need to look at replacement of the REM. In Network Menu take note of the 2 x software part numbers of the REM which show up in the report. Chances are that a replacement REM from the same model year/body type will have the same software. Of course the replacement REM must be from an AWD model. We swapped the REM on our 2006 XC90 with one from a 2007 model and even though software numbers are different all functions operate so the matching here is not crucial and you may not require a dealer to reprogram.

[ILOVEPV]

Yes,pic is after reset, so these returned straight away.. (There were a couple of faults connected to the ECM that did not return, ECM-666x Glow relay control and (now I realize it was not in my pic above which I thought..) REM-4A48 Fuel level, gas signal too low.)

I did find the Xenon calibration when on VIDA, but it returned a "Calibration not ok" (not exact wording..)

Ok, I will not bypass the REM regarding the AWD, but something seems to happen in the REM between fuse #23 and the pin on the back side where the cable to DEM is connected. I have no idea what the unit is doing with the supply in-between.. I did not have the communication plug disconnected at the DEM when measuring, but still, the communication should not pull the supply low at the pin on the REM when the supply cable is not connected there...? I will reread with both plugs pulled though, hopefully tomorrow to rule out (it is freezing cold out now -19 degC..and no garage..wish I was "down under" too sometimes!)

To go through the DEM sounds like a good idea, but i would like to see that REM signal at 12VDC first though. Is it possible to remove the DEM and temporarily seal area off so it is possible to drive, or is that nothing to recommend?( I do need access to the car)

Thanks for REM part no info. I was wondering if they had the same unit on all cars or if it was special on the AWDs, now I have the answer!

[oragex]

The haldex pump can go bad usualy form a clogged filter, the DEM unit can get corroded, the colar spline can get worn. Xemodex can help with the DEM, read a bit on their site

[ILOVEPV]

The only thing unique to an REM is the serial number and part number (also reported in Network) The rest of the values can be programmed and updated. So even if you get one from a non AWD sedan the programming can be altered to suit your car.

The software numbers reported in Network are not the ordering numbers for the software, but are software versions that can be duplicated by the dealer or by our software gurus here on forum.

I believe you can't drive without the unit attached but more experienced members may be more familiar

[ILOVEPV]

Thanks for the input, I have assembled my REM again after checking for discolorations etc on the boards (found none) and checked all fuses. Will try in car later today but have little hope for any improvement.

Sounds good that more REMs could fit with some "hands on" activities!

[ILOVEPV]

Does anyone know where the REM is grounded so that that aspect can be ruled out?