Hi all:

Well, here's a disappointing one... First, my specs:

Model: 2004 XC90, 2.5T. 280,000 kilometers
Problem: "Anti-Skid Service Required" Message

I have had this message for a while now. My normal independent mechanic could not fix, so I found a Volvo-only specialty repair shop, which had high ratings for customer service.

First time I brought it in a few weeks back, they scanned it and said the following needed to be changed based on the error codes:

1. Steering Angle Sensor
2. AOC Pump
3. AOC Fluid
3. Differential Electronic Module (DEM)

I thought long and hard on this one. The repair will was expensive but better than the dealership. So I bit the bullet since I really like the vehicle.

Last week I brought it in and they told me that the SAS didn't come in on time so they had a used one which they used. So SAS, AOC Pump and AOC Fluid were changed. When they took out the DEM and sent it to rebuilder, the rebuilder tested it and said it was fine. So they called me and told me the great news that the DEM is OK and that the bill would be lower. Wonderful, I said and I was getting ready to get the car.

Unfortunately they called me about an hour later and told me when the DEM went back in, the error came back. So they wanted to keep the car for another day. I said OK.

I needed the car back at the end of the following day so that morning I called them and asked what they would check. They said that the problem is a communications issue on the car's network, they brought in an engineer to help diagnose and they said to check the wiring and then check the rear differential module. So they spent last Friday checking wiring. No issues. They checked the rear differential module. No issues. They wanted me to bring it back this week. So I did yesterday and left it all day yesterday.

So they thought it was the DEM again. So they had a spare one that they had, replaced it, and no change. So the issue is definitely not with the DEM. The new SAS also showed up and they replaced the SAS again and it made no change so it wasn't that.

Currently issue is DEM is not recognized by network and not communicating with brake control module or CEM.

I spoke with them this morning and they told me that unfortunately they are not able to isolate where the problem is, and that they have to call it quits since they spent all day on it yesterday and are not able to figure it out. I will have to bring it to a dealership if I want to have it looked at further.

I just spoke with them and said if it is a communications issue, can they please check the brake control module or CEM while they still have the car. While they did not charge me for the diagnostic work yesterday, they did tell me they would charge me for the BCM and CEM check today. I said, go ahead. Better they check it than the dealership. They did warn me that the engineer told them that it was unlikely that either was causing the issue so I said, well, I want to rule it out so please check it.

Does anyone have any other ideas what could be wrong here? I already spent $1400 on the replacements plus will spend another $500 on diagnostics today...I would just have for these last three weeks to be for nothing. But I don't have an unlimited budget to sink into this car with so many kilometers on it.

 

I would be curious how they are "checking" the modules. There isn't really much of a check. If the BCM or CEM wasn't online, it would be apparent right away without needing to charge you more to "check". It sounds like they haven't diagnosed anything. They threw all parts in the system at it.

 

That's correct - sorry, I may not be explaining this properly...they did see right away that it's not online...I requested that they take the BCM and CEM out to check to see if it is faulty - they actually told me this morning that they essentially gave up and are not sure what the issue is. When I asked for the error that is still there, they said that it is a communications issue between the BCM, CEM and DEM.

To be fair, this shop is very reputable (fantastic customer ratings) and they haven't charged me for the extra diagnostics yesterday. Originally what they changed out is based on what the scan was telling them was the culrprit (SAS, AOC pump, fluid, and the DEM). They changed it all except for the DEM which they sent to the rebuilder and that's they it was discovered that the DEM was OK. When they put the DEM back in, the error was still there but now it was a communications error between the DEM, BCM and CEM. Again, it was me that told them to take the BCM and CEM out to check the modules by the rebuilder.

 

Okay so by "check" you mean "remove and send to a rebuilder." That makes more sense.

The CEM and BCM are offline? I doubt that.

Is there power to the DEM?

 

Yes, they have checked that the fuse is fine and there is power to the DEM.

 

If there is power and ground to the DEM and it doesn't communicate, it's a DEM unless the CAN wires to and from the DEM are open.

Did they program the used DEM?

 

But they sent off the original DEM to the reubilder already and it was thoroughly checked and sent back indicating no faults or defects found, from the rebuilder.

 

There are only 4 wires to the DEM. It's just a computer module.

If power and ground are there and the two communication wires are good, the fault is with the module.

I don't know what kind of testing the rebuilder does. But it isn't very difficult to diagnose. Throwing a used one in without programming isn't going to work either.

 

I wish it were that straight forward. They did reprogram the spare one that is known working and it didn't make a difference.

 

I also don't know if programming a used one will work. A lot of indy shops don't have the ability to do downloads.

Without having the codes and being able to check the car myself, it sounds like a DEM.

 

I have an update...the rebuilder called the mechanic back who just called me back. So the CEM turned up clean (which is good) but the brake control module (BCM) is confirmed faulty. They said that definitely can cause these issues, but no guarantees that will solve the AWD problems. I told them to go ahead and repair the BCM. Now...in that time, I had them check the timing belt and the belt is cracked. So I need to fix that as well. But I told them I will see how the repaired BCM responds to the XC90. If the AWD works again, I will go ahead and fix the timing belt. If the BCM does not fix the AWD, I'm going to walk away and get another car and sell this one, which will be sad.

 

Rats - another update....repaired BCM came back, they put it in...still Anti-Skid message and communication error.

 

What codes are stored and what are the CAN voltages?

 

hijacked...
only CEM-1A64 with Anti-skid service required on the dash.
How do you test the CAN voltages

 

If you have code CEM-1A64 (no communication with DEM)...the CEM, REM, DEM, BCM were all validated as good working units. All wiring and connections tested and passed. Could the modules not be communicating any longer because they somehow became divorced? Is there any way I can send them for counseling and they can continue in their marriage?

My thought is all modules were sent out on separate occasions and validated as good individually. Can the rebuilder validate all modules work as a group and in fact communicate with one another if all were sent out at the same time?

As you can tell I've taken over this vehicle and I'm scrounging for possible ideas aside from finding something that the PO's mechanic overlooked.

Thanks for any help

 

I have the same problem on my xc 90 2005 2.5 T.
No connection between DEM and VIDA program.
Test with other used DEM,impossible to connect to DEM.
Any solution ?

 

Bueller? Bueller? Anyone have an answer here???

 

Check every fuse and make sure all fuses are in he proper slot.


Had some of the same problems and more. Diagnosed as bad CEM for twelve hundred bucks. Couldn't afford so after some thought decided to start checking fuses. Found Accessories control module and Rear electrical module fuses missing or misplaced. Replaced those and knock on wood, no problems in thousands of miles. I would have been out the twelve hundred bucks and the problem still wouldn't have been fixed.


Point is sometimes even the pros miss the simplest things.


Good Luck

 

First, you need to install a NEW NEVER USED steering angle sensor. Then, you have to calibrate the new sensor. Volvo also recommends a software download for the new steering angle sensor.

I've replaced many of these. Installing a used sensor that is already calibrated to another vehicle will not work.

By trying to save three cents, you're spending three dollars, so to speak.

 

was wondering if anyone can help? have a 2007 Volvo xc90, 110K miles, anti skid warning been on for a couple months, DEM not communicating with vehicle, AWD fuse was blown, after replacing the fuse, it immediately blew again. was wondering if it could be a wire issue or something not ground, or is the DEM bad.. all fuses seem to be in right places and no other fuses blown.. also may be a coincidence, but this issue seemed to happen after water built up under driver seat area, yaw sensor unaffected.. thanks in advance