53 replies to this topic

[NJGreenBudd]

So I suspect some issue with the DEM is developing on my 2002 Volvo S60 2.4T AWD with nearly 180,000 miles. I am losing AWD, I think it's almost never working these days, easily getting wheelspin in the wet and even dry at times if I push it. I have already replaced the angle gear around 100,000 miles, then completely resealed the newer one at 150,000 and did the collar gear at that point so I don't think it's the angle gear. That leaves the rear differential components as primary suspects.

Obviously first thing I need to do is lift one front wheel and spin it with the car in neutral to see if the angle gear is still intact - even though it's up to date I need to rule it out.

Then onto diagnosing the rear diff. I have seen the TNN for the pressure switch but how do you tell if it's the sensor, aoc or dem itself? Is there info on this in VADIS, VIDA? I have VADIS at home and VIDA on it's way from overseas as we speak?

So in the meantime, is there anyway to tell by hand what's happening with the rear diff?

I have been searching for info and will post up the TNN and some other stuff when I get home. Please feel free to add anything DEM related to this thread whether it's specs, part #'s, experiences, etc...

Thanks and have a great day guys!
NJGB

[NJGreenBudd]

Okay so found very good info on the system:

[Che'_Moderator]

I know Josh is lurking but in the mean time:
http://v70r.com/foru...post__p__121631

[NJGreenBudd]

Very good information, thank you Che, and Josh too.

From ihatespeedbumps on v70r.com:

DEM diagnostics follow this order:

1. With vehicle up in the air, ensure the rear driveshaft is turning when in gear.

2. If the driveshaft is not turning, remove the angle gear and inspect the coupling sleeve between the angle gear and transmission. If the splines are not stripped, replace the angle gear.

3. Check for codes in the CEM for communication faults.

4. If the driveshaft is spinning, access the Differential Electronic Module (DEM). If there is no communication with the DEM, check for power on the Blue/Red wire, ground (Brown and Black wires) and network integrity by checking resistance between the Green and White wire. With the battery disconnected, there should be 60 ohms between the two wires.

5. Check the Active On Demand Coupling (AOC) oil pump for proper operation. After startup, the DEM will apply power and ground to the oil pump and you should be able to hear it run. You can manually apply power and ground to it. If it does not run, replace the oil pump. The oil pump can draw excessive current and blow the fuse for the DEM, causing the lack of communication.

6. Check DEM live data and monitor the AOC oil pressure sensor. Key on engine off reading should be 0.00 (+/-.08MPa). Start engine and recheck. With the oil pump running, pressure should rise to .38 (+/-.08 MPa)

7. Review Tech-Net Note (TNN) 40-02 and perform DEM and Central Electronic Module (CEM) software upgrade if needed.

8. If the DEM will not accept software or there are repeated communication problems after the download and all checks are good, replace and reload the DEM.

Does any body know if the parts( DEM, oil pump, etc) are the same between between the AWD models like S60R, XC70, XC90??
Do you need a software reload if you replace the DEM?

Thanks again all!

[Che'_Moderator]

My bet is its the sensor. If its the actual DEM than you are in for a dealer trip to have it flashed. Figure 400 dollars lighter at the end of the day.

[NJGreenBudd]

I'll keep this updated and let you know what it was. Shoot $400 for AWD again is nothing, I was more worried about $2500 or so.... lets hope.

[Ihatespeedbumps]

Thanks for finding the link Chuck

OP: It's very important to make sure the rear wheels aren't turning before proceding. Basing a diagnosis on wheel spin alone is not adequate. Have you had any messages related to the AWD pop up in the DIM?

If the rear wheels are not spinning, DTC's stored in the DEM are of great help. Like Chuck mentioned, pressure sensor failure is pretty common, though, I have personally replaced quite a few faulty DEM's. They are much more costly than $400, the part alone runs about $1100 plus labor and software. The good news is that Xemodex rebuilds them for a fraction of the price with a lifetime warranty.

One note about the 02 S60 AWD. This model is unique in that it was ONLY AWD model to have an AOC filter and it does have a regular service interval, every 60k IIRC.

Bottom line, make sure the rear wheel don't spin, read the codes when you get VIDA up and running and report back here. We'll help you get it resolved.

[NJGreenBudd]

Thanks for the reply Josh. I fully understand the need to verify rear wheel enagement before proceeding, I can do this tonight if I'm lucky. I have had no messages in the DIM regarding AWD yet, based more on the feel of the cars handling thus far.

What do the sensors cost these days? I heard they are offering them independently of the DEM now.

I did see that filter listed in the diagram above which is 2002 S60 AWD specific via VADIS. Can we replace those? I am hesitant to admit it but will disclose that I have never serviced the rear diff at all, never checked the fluid or anything so I'm quite curious to see what's going on back there.

Thanks so much for the help fellas, I do greatly appreciate it.

-Brandon

[NJGreenBudd]

Ok little update, I finally had time yesterday to check the operation of the angle gear and indeed the driveshaft does spin when the front wheel is turned. I looked at the DTCs in VIDA with my DiCE tool and I didn't see any codes and it didn't want to read the DEM. I will give it another shot tonight and spend more time looking in VIDA to see if I can access DEM live data.

Thanks for all the help!

[Ihatespeedbumps]

So, when you click on the "network" tab the DEM is illuminated in orange?

[NJGreenBudd]

No the DEM box was white in color:


Here is a screenshot of the DTCs, you see anything AWD related:

[NJGreenBudd]

3. Check for codes in the CEM for communication faults.

4. If the driveshaft is spinning, access the Differential Electronic Module (DEM). If there is no communication with the DEM, check for power on the Blue/Red wire, ground (Brown and Black wires) and network integrity by checking resistance between the Green and White wire. With the battery disconnected, there should be 60 ohms between the two wires.

So I tried again last night to check for any AWD related codes and can't seem to find anything at all. I get the same DTCS as shown above and can't access the DEM live data at all. The DEM is shown in white and nothing happens when I click on it. But should I be trying to access the DEM directly or through the CEM? I am a bit confused and don't know if I'm doing something incorrectly or if I am missing communication to the DEM entirely. Wouldn't I get at least some sort of fault if the DEM was disconnected.

I am going to try to look through the CEM closer tonight and might go on to test for power and network integrity. Thanks for any help here.

[Ihatespeedbumps]

I am stumped. The DEM showing white indicates that VIDA does not recognize the car is AWD. If the module were offline you'd have a communication fault and under the network tab the DEM would be illuminated orange. When you profiled the vehicle, you selected "read vehicle" in the AME market? After that you did select the AWD trans?

[NJGreenBudd]

I don't know man, I just tried again this morning and the same thing, DEM is white and unreadable and no codes in the CEM that indicate communication fault.

Yes it's selected as AWD. Very strange indeed, it like it's ghosted. I suppose I can still check for power and such but don't know what this indicates so far.

[NJGreenBudd]

So I just went out and lifted the car in the air, tested for power between the blue/red and brown wires and it was 12v. Tested the resistance between the green and white wires and it was 60.8ohms with the battery disconnected. I am pretty sure I can hear the oil pump running when the car is running is on too. Could it just be low on oil or clogged AOC filter? I tried to open the plug but it was tight, I'm soaking it now.

Still weird that it doesn't show in VIDA...

As I'd like the check the live data:

Check DEM live data and monitor the AOC oil pressure sensor. Key on engine off reading should be 0.00 (+/-.08MPa). Start engine and recheck. With the oil pump running, pressure should rise to .38 (+/-.08 MPa)

[Ghost Shadow]

take the DEM off the car, see if crud comes out. my xc90 had aoc fluid inside it all on the circuit board. i used a razor blade and opened it up then resealed it with silicone. plus i had a dem 0007 and 0006 code

[NJGreenBudd]

Just to make sure I was doing everything correctly I went ahead and hooked up DiCE to my 2006 XC90 V8 AWD and was able to communicate successfully with the DEM and view it's live data.

[NJGreenBudd]

Im kinda at the end of my rope with this problem, it's basically already winter and i'm still in FWD. I tried to detect the AOC pump going today again and it's not running, I know cause I unhooked it and it sounded the same as when it's connected, I also unplugged it and tested the leads coming to it for voltage and there was none. It looks like the DEM is the fault here.

I found this pdf for troubleshooting the DEM from XemodeX:
http://www.xemodex.c... Flow Chart.pdf

I just find it odd the DEM can die and not generate some fault code. Anybody have anything else they want to add before I bite the bullet and send it off to XemodeX

[NJGreenBudd]

I pulled the DEM today and am a bit confused by what I see and found out. I thought the sensors were supposed to be sticking out from the housing but mine looks different:












Hooked up some 12v directly to the AOC pump and verified it does work:





Interestingly enough, I scanned the car with DiCE with the DEM unplugged and found a CEM-1A64 DTC - Communication with AOC control module signal missing. This goes away once the DEM is plugged back in. When I read the Fault tracing for the 2002 AWD it doesn't say anything about LIVE DATA, just testing the circuits. The 2006 AWD Fault tracing goes into the process of accessing the Live Data..... I wonder if there is a difference between my version of Haldex and the newer ones that makes mine show white in VIDA??

[NJGreenBudd]

Newer Haldex from 2003 onward for comparison: