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Pete, Technician
Category: Volvo
Satisfied Customers: 27813
Experience:  Over 17 years diagnosing and repairing various automobiles at a dealer and independently.
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I would be very glad if you could help me with the following

Customer Question

I would be very glad if you could help me with the following issue with my 2005 Volvo S60 2.5T AWD.
The car showed me the "Anti-Skid service requied" message. First just after driving 20-30 mins, later was the message from the first second there, and didn't went away since.
I was already at two official Volvo dealership to solve the problem, but they just seem to be not very competent or helpful. First dealer said that there is maybe a problem with the DEM or with the AOC pump, they wanted to swap it, but they couldn't say for 100 % that the problem is with this components. As they are very expensive and the dealership couldn't convince me, that the problem is really the DEM/AOC pump (in the first place they said that there is propably the SAS what went wrong...), I took the car to another Volvo service.
They have provided my at least the list of the fault codes (whey couldn't help me further, which I think from an official Volvo dealer/service is really sad...), the codes related to the AWD, Anti-Skid systems:
BCM-0094: Communication between control units, Communication problems with DEM
CEM-1A64: Communication with AOC control module Signal missing
DEM-000B: Oilpressure Faulty value
Another Haldex "expert" has after a 5 hour long struggle said, that there is a CAN-Bus communication failure and he cannot determine, whats wrong with the AWD.
Could the DEM-000B, the bad/misreading oil- and temperature sensor lead to all this problems? If the sensor sends faulty values to the DEM, the DEM will not respond to the ECM and the BCM, am I right? Therfore the ECM and the BCM will give a fault code, stating, that the DEM is not communication. Could my misery be solved with just the changing of the oil pressure sensor in the Haldex unit (and the changing the AOC pump will be also good...). The car has run 120k km's, and I think the previous owner didn't paid that much attention to the Haldex/rear differential. I have changed oil and filter in the Haldex already.
When the oil pressure sensor is changed, i still have to go to the dealer and ask them to delete all the fault codes?
Thank you, ***** ***** can provide me a correct answer!
Submitted: 1 year ago.
Category: Volvo
Expert:  Pete replied 1 year ago.

My name is ***** ***** I am a professional here at Just Answer. I noticed that your question had not received a response and thought I would see if you still need help with this.I apologize for the delay and I hope I can still assist you with this here.

If there is a wiring fault between the control units/ecu's this can cause this issue here as well as a fault with one of the components the DEM or the AOC.If one of these is shorting out internally this can cause communication faults as well.If the wiring was not checked this should be done first to see if any issues are found.If a fault is found with the wiring the wiring will need repaired to correct this here.If no wiring faults are found a dealer should be able to test and determine if one or both of these control units are at fault needing replaced.

Once the oil pressure sensor is changed the codes will need cleared out with a scan tool to turn off the check engine light but the light will most likely come back on until the communication fault codes are corrected.

If more help is needed, use the reply tab to continue our conversation. If no further assistance is needed, kindly rate my service.You can rate at any time and we can continue to work on your question as this will not close out your question.Keep in mind in some cases it can be difficult to fully diagnose or help repair your vehicle without seeing it and I work on delivering the best possible answer from what I see to work with.

Thanks Pete

Customer: replied 1 year ago.
Hi,so you recommend to replace first the pressure sensor in the Haldex, then clear the codes? If this doesn't solve the problem, then the wiring should be checked?I afraid that if the changing of the pressure sensor doesn't help me further, than I will be struggling to find somebody to check the wiring. As said before, no one at the dealerships could help me further apart from providing the fault codes, therfore I have serius doubts that they could check the wiring.The DEM-000B fault code would't appear in any other case, just in the case of a faulty sensor, am I right? I mean, that the code DEM-000B could not be generated through CAN-Bus communication failures, right?Is there a way to check the wiring myself, or should it be checked through with a software, special hardware?Regards, Péter
Customer: replied 1 year ago.
Yeah and one more thing...BCM-0094: Communication between control units, Communication problems with DEM: DTC not active!
CEM-1A64: Communication with AOC control module Signal missing: DTC not active!
DEM-000B: Oilpressure Faulty value: DTC active!Does "DTC not active" mean that the trouble code that it was in the time of the trouble code reading not active - just maybe appeared one-or-two time in the lifetime of the car?
Expert:  Pete replied 1 year ago.

The DEM-000B can set with a faulty sensor or any other mechanical issues with the oil pressure system like a regulator or pressure relief valve.This wont cause the communication fault codes though.This code will have to be diagnosed properly to pinpoint the fault then from there it can be repaired to correct this issue here.

You might have to check for any repair facilities in your area that are somewhat familiar with this model here to see if they can check over the wiring for any faults needing repaired.The oil code will not cause the other codes to set here.If the communication codes are not active then I would replace the oil pressure sensor and clear all codes and see if any of them come back at all.They may not and may have been a one time fluke fault that no correction is needed for in some cases and clearing them out may keep them from displaying again.You might just start with this first.Find a shop or dealer that can clear out these codes and then operate the vehicle and see if anything comes back at all.If none come back then your o.k. from here and no repairs are needed.

Let me know if you need anything else and feel free to rate my help here.

Thanks Pete

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