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Discussion Starter · #1 ·
2008 Volvo XC90 3.2L.

The message comes on immediately and never leaves. I bought a VIDA thingy and here are the results:
CEM-1A64 Communication with AOC control module Signal missing
BCM-U011400 Lost Communication With Differential Electronic Module
BCM-C004664 Brake Pressure Sensor A/B Algorithm Based Failures - Signal plausibility failure
CCM-DD33 Damper motor, defroster No communication
CEM-8FF0 Rain sensor button Activated too long
I have tried replacing the yaw rate sensor as suggested online, but that did not fix the issue. I have heard it may be due to a faulty steering angle sensor as well, however it seems that when that is the issue the code is not 100% prevalent.

I have also heard that balancing/alignment can cause the message to go away. But it seems like from the diag that it's probably related to the AOC control module or the DEM? The DEM is another common issue, it seems.

Any suggestions for how to proceed? I am not looking to spend >$500 fixing this, but boy I would appreciate having AWD this winter.

Would greatly appreciate any help! Thanks!
 

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You can double click on the codes in VIDA and get more info, including repair possibilities. Otherwise, you can get more info on DTC's here:

I believe that the first three codes you list will each individually trigger the anti-skid message. If there is a yaw sensor error or a steering angle sensor error; you can expect to see DTC's for those components listed. Tire balance or alignment will not play a role, with the possible exception of active steering. There are many threads in the XC90 forum here covering those issues. I realize that the "Search" function here is difficult to master, but you will find that the effort to master it will pay off. Also, if you have a chrome-based browser, the Google etension to search the current site will do a great job:

 

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2008 Volvo XC90 3.2L.

The message comes on immediately and never leaves. I bought a VIDA thingy and here are the results:
I have tried replacing the yaw rate sensor as suggested online, but that did not fix the issue. I have heard it may be due to a faulty steering angle sensor as well, however it seems that when that is the issue the code is not 100% prevalent.

I have also heard that balancing/alignment can cause the message to go away. But it seems like from the diag that it's probably related to the AOC control module or the DEM? The DEM is another common issue, it seems.

Any suggestions for how to proceed? I am not looking to spend >$500 fixing this, but boy I would appreciate having AWD this winter.

Would greatly appreciate any help! Thanks!
I replaced the steering angle sensor for $320.00 and the anti - skid never came back on my 07" V70
 

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Discussion Starter · #4 ·
I replaced the steering angle sensor for $320.00 and the anti - skid never came back on my 07" V70
Did your anti skid message come up immediately when you started the car? From what I've read online it seems like when it's the SAS at fault, the error message is not 100% prevalent. The other commenter also mentioned that I would probably get a SAS specific error code if it were the SAS
 

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My anti-skid message was caused by the anti-locking brakes motor brushes (worn out). I replaced the motor from a junk donor, and the message went away for over 20k miles. The problem with the anti-skid message is that many things can cause it. Fortunately, VIDA can pin-point the exact cause.
In my previous post, I linked the wrong Google site search results (now corrected).
This deals with your AOC fault:
I would start by inspecting the wiring to the Haldex to be sure it's intact.
 

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When I start the car the anti skid temporary off light (or something like it) comes on. If the car is travelling in a straight line the light goes out but when making a right hand turn the anti skid service required light comes on. I got another clock spring thing (SAS) from the auto wrecker but haven't tried it yet. I'm not expecting much due to the obvious old age of the wires.
 

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Did your anti skid message come up immediately when you started the car? From what I've read online it seems like when it's the SAS at fault, the error message is not 100% prevalent. The other commenter also mentioned that I would probably get a SAS specific error code if it were the SAS
When the message appeared it was always when the car was started. It started to appear maybe once a month or longer then started to appear more often as the year went on
When it started to appear every week or so, I changed it. Also when it did appear I could stop, restart the engine and drive and the light would sometimes go out until the next time.
 

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When I start the car the anti skid temporary off light (or something like it) comes on. If the car is travelling in a straight line the light goes out but when making a right hand turn the anti skid service required light comes on. I got another clock spring thing (SAS) from the auto wrecker but haven't tried it yet. I'm not expecting much due to the obvious old age of the wires.
There's some element of cause-and-effect, there, so it may be the right solution. Wiring inside your car and steering column should be well protected. There's no wiring that twists and turns with the steering. That's the function of the "clockspring". Be careful that the wheel is centered and the take-off SAS is properly oriented when you install it. Plenty of threads covering correct alignment here on Swedespeed. If you have VIDA available, you would possibly have a Steering Angel Sensor DTC to confirm, like one of these:
Azure Rectangle Font Parallel Circle
 

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To the OP jacobkuca

I would personally start with the brake pressure sensor since it says plausible signal issue as well as it is cheaper/easier to start with a sensor rather than modules or wiring. Anti-skid relies on the brakes, but is not needed with AWD. That's another reason to start with the brake pressure sensor. Could the pressure sensor create a possible issue with the AOC module, possibly due to CANbus.

Here is a thread Ggleavitt tried to help with another member and the brake pressure sensor: Brake pressure sensors

Could you tell us more about your XC90? miles, location, history, when did you acquire it, etc.
 

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Discussion Starter · #10 ·
My anti-skid message was caused by the anti-locking brakes motor brushes (worn out). I replaced the motor from a junk donor, and the message went away for over 20k miles. The problem with the anti-skid message is that many things can cause it. Fortunately, VIDA can pin-point the exact cause.
In my previous post, I linked the wrong Google site search results (now corrected).
This deals with your AOC fault:
I would start by inspecting the wiring to the Haldex to be sure it's intact.
Thanks,

I checked the wire harnesses, they look fine. Message still comes up immediately after reseating the harnesses.

According to this: DEM Diagnostic Flowchart for 2005-2010 Volvo S60 AWD, XC60, XC70, XC90 | XeMODeX Inc., there may be an "open circuit between wiring harness between REM and DEM"- I unplugged the bigger connector from the DEM, switched ignition to position 2, and checked the voltage across pins 1 & 2 - it was millivolts. Fuse 23 still intact and powered.

Does this seem in line with the error codes I'm receiving?

Suggestions on how to proceed?
 

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To the OP jacobkuca

I would personally start with the brake pressure sensor since it says plausible signal issue as well as it is cheaper/easier to start with a sensor rather than modules or wiring. Anti-skid relies on the brakes, but is not needed with AWD. That's another reason to start with the brake pressure sensor. Could the pressure sensor create a possible issue with the AOC module, possibly due to CANbus.

Here is a thread Ggleavitt tried to help with another member and the brake pressure sensor: Brake pressure sensors

Could you tell us more about your XC90? miles, location, history, when did you acquire it, etc.
^^I agree.
You don't have any of the typical SAS trouble codes so no need to go in that direction (at this time anyway!😉).
If you follow VIDA guided fault tracing for the pressure sensor code it will have you monitor the signals from the two pressure sensors and from there you should see the pressure change when the pedal is pressed. If you don't see a change the sensor is likely at fault.
If the car has not had regular brake fluid flushes the sensors can get gummed up with brake fluid sludge. What you might do is take them out for a look. If the openings in their ports are clogged you can try cleaning them with some hot soapy water, just blow the wire terminals dry before refitting. And, if they are clogged with sludge that's a good indicator you should flush the brake fluid more often.
 

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Discussion Starter · #12 ·
^^I agree.
You don't have any of the typical SAS trouble codes so no need to go in that direction (at this time anyway!😉).
If you follow VIDA guided fault tracing for the pressure sensor code it will have you monitor the signals from the two pressure sensors and from there you should see the pressure change when the pedal is pressed. If you don't see a change the sensor is likely at fault.
If the car has not had regular brake fluid flushes the sensors can get gummed up with brake fluid sludge. What you might do is take them out for a look. If the openings in their ports are clogged you can try cleaning them with some hot soapy water, just blow the wire terminals dry before refitting. And, if they are clogged with sludge that's a good indicator you should flush the brake fluid more often.
Thanks, I will check them out... currently downloading windows 7 to put in a VM so I can reinstall VIDA, I guess it broke when I upgraded to Windows 11.
 

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Another thing about the brake module BCM and brake pressure sensor, the AOC will rely on the anti-lock brake sensors to sense slippage. Since there is a brake pressure sensor issue, the AOC system communication could be shut down, almost like a limp mode for the brake module. Another reason to start with the brake pressure sensor.

Also, since brakes are needed to drive safely, it's good to start with the part related to the risk of safety.
 

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the AOC and DEM are very close to each other in the rear differential. Check the wiring if everything is connected there, otherwise it's common for the DEM to fail and it's not a cheap replacement. Try clearing the code and disconnect the wire if it shows the same code upon start up. Nothing got worked on that area such as fluid changes?
 

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I'll guess you have two, maybe three problems- the DEM is not communicating over the CAN network, the pressure sensor "set" has experienced an anomaly and there's an issue on your LS CAN bus (all the greyed out modules) which could a function of the DEM being down but you already know that's an issue (module is greyed out).
Possible it could be harness but I might walk through the fuse 23 path one more time and make sure it's whole (or blown).
Could trace the wire from the output of F23 all the way to the connector as a sanity check. As well, forgive me for asking but the 1 and 2 pins you measured were top/bottom and not side/side, right?
Automotive lighting Rectangle Gadget Font Gas


When you're back in VIDA with the vehicle connected, check the timeline for the BCM code. Error being reported is a difference between the A and B sensors. Your resolution path for this was as noted above (clean and recheck). I have a randomly failing "B" pressure sensor in my Ocean Race, will replace both in a couple weeks when I re-do some cleanup work (front timing cover).

If you look at the VIDA screenshot, you'll see the Network tab has the same color triangle as Fault trace tab. Everything from the CEM to the left and also including the DEM is your high speed (HS) bus, from the CEM to the right (excluding DEM) is your low speed (LS) bus.

Once you get VIDA and DICE back to working do another read and repost, maybe something will have changed. And once you get all of the modules reporting, someone can help with the other codes that you may pick up.
 

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Discussion Starter · #17 ·
I'll guess you have two, maybe three problems- the DEM is not communicating over the CAN network, the pressure sensor "set" has experienced an anomaly and there's an issue on your LS CAN bus (all the greyed out modules) which could a function of the DEM being down but you already know that's an issue (module is greyed out).
Possible it could be harness but I might walk through the fuse 23 path one more time and make sure it's whole (or blown).
Could trace the wire from the output of F23 all the way to the connector as a sanity check. As well, forgive me for asking but the 1 and 2 pins you measured were top/bottom and not side/side, right?
View attachment 139495

When you're back in VIDA with the vehicle connected, check the timeline for the BCM code. Error being reported is a difference between the A and B sensors. Your resolution path for this was as noted above (clean and recheck). I have a randomly failing "B" pressure sensor in my Ocean Race, will replace both in a couple weeks when I re-do some cleanup work (front timing cover).

If you look at the VIDA screenshot, you'll see the Network tab has the same color triangle as Fault trace tab. Everything from the CEM to the left and also including the DEM is your high speed (HS) bus, from the CEM to the right (excluding DEM) is your low speed (LS) bus.

Once you get VIDA and DICE back to working do another read and repost, maybe something will have changed. And once you get all of the modules reporting, someone can help with the other codes that you may pick up.
Checked the fuse again to be sure. Both sides at 12V, multimeter says it's continuous. I'm positive it's the correct fuse, and I don't know why but I did check every fuse back there and all of them are fine.

I looked around the trunk area for obviously broken wires but didn't see anything suspicious.

Yepp, top/bottom... I just checked it again to be sure the probes were connecting to the contacts and the voltage actually rises from 0 to 200mv, says "overload" for a split second and then resets to zero and rises again. Not sure if that's important, probably just a result of the multimeter checking for a voltage but yeah it doesn't show 12V.

VIDA back up and running, the pressure code is gone now.
I am pretty sure that I cleared the codes before I checked the timeline (whoops), there were a lot of voltage codes that I thought might be due to the fact that it was in low battery mode so I cleared them and started the car.

VIDA screenshots: | |
@lincolnshibuya: Nothing got worked on in that area since I've gotten the car, I'm not aware of any fluid changes in that area.

I see that DEM repair service isn't cheap, but it seems that if you can find a suitable donor (matching PNs) it's just plug and play, I see a decent amount on eBay for <$100... I would totally just buy one to test it out if the harness were providing power to it, but given that I can't read a voltage from the harness I don't think replacing the DEM would help just yet.
 

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BCM error for pressure sensor might go away for a while then come back, at least that's what I'm getting and that's after a couple BCM calibrations to baseline the system. I still think the advice of @vista88 is spot on and the error will come back but if it's not there right now, it's not there.

That leaves you with the uncommunicative DEM. Harness seems to run to a junction 54/74, (see image for detail) splitting to REM (pin1- 12VDC via F27 then F23) and to CEM (pins7-8 via CAN). If indeed you have a harness problem, that's logically where to look next.

Map Slope Font Parallel Circle
 

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Discussion Starter · #19 · (Edited)
Okay, I'm an idiot. I could swear that I checked every fuse, but it turns out that A) I misidentified fuse 23 and B) fuse 23 was in fact blown after the test. I checked the pump with 12v and it does operate.

Looks like it's the DEM at fault - which I take as good news...

I wonder how easy these are to fix...

Looks like I need the "5wp33504" DEM... would be great if anybody knew if a different one worked, as I can't find this one online.

I have also seen conflicting information regarding whether or not these are swappable. Think my best bet might be to get it repaired, but getting around will be an issue. Given the diagnostics and error messages, does it seem like there's a good chance the AWD will be fixed if I get the DEM repaired?

Anybody know of any repair services within the US for a bit cheaper than Xemodex? $700+ is a bit much for me. I see some services that are out of the country for $100-200, and some that are in the US and cheap but apparently take weeks to complete an order according to customer reviews (Volvo Differencial Electronic Module &Audi DEM. Halex 01-2011 Repair Specialist).
 

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I have seen xc90's as new as 2007 at the auto wreckers and that's where I would be looking because I don't consider these gas burners worth putting real money into. On the other hand the wife has been talking about a new Volvo so I guess keeping them going is worth it.
 
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