Urgent help please
 

Hey everyone I own a 2004 Volvo s60R, I started seeing the abs warning light show up on my dash very occasionally. Over the last few weeks became worse untill last week it was on continuosly.
The fault codes are as follows;
Central electrical module
CEM-1A64 AOC control module signal missing.

DEM differential ECU
DEM-E000 module communication faulty.


ABS
ABS-0100 coms with engine ECU
ABS-0094 coms with ECU, problems with active on demand
ABS-0115
Cons with steering wheel angle sensor signal missing
ABS-0148 coms between control modules faulty configuration

Battery voltage is 11.8 volts.

The ABS ECU has just come back from ECU Testing with no faults found.

There is no active suspension, no abs no traction control. I am using launch diagnostic equipment.
However I can't distinguish what's causing the issues can anyone help me please?

Basics first so make sure the battery is fully charged and in good health.
Low system voltage can create spurious fault codes.

Plot the individual wheel speeds to make sure there's no anomaly to eliminate abs rings and sensors.

Check back if the above don't work.

Is the awd working or is it running fwd only? Get it onto grass or gravel and see if you can spin the front wheels. Suspect the DEM has failed, that put on the anti-skid (I think) on my dads XC70.

Thank you for replies
Brake failure
Anti skid traction controller reduced.

The odometer is displaying dash instead of miles.

The abs sensors spear to be working as should.

Battery is charged. However still displaying 11.8 volts.

If DEM is faulty, how do a diagnose? Was wondering if the DEM could drag down the canbus causing the abs and steering wheel angle to show fault.

That needs changing.

+1 for battery. Always causes many fault codes when they are on their way out.

Try a Volvo dealer (they are surprisingly cheap for batteries) or failing that try Tayna Batteries in Abergele/Rhyl (they deliver).

If you battery is still reading 11.8V after being charged then it needs replacing.

Only then can you actually begin fault finding as some of your codes could just be because the voltage is so low you are getting false error reports because voltage inputs are out of range.

If you do have a failed DEM then it will cause a lot of other errors as well, I know from experience on my own XC70.

Also the steering wheel angle sensor error can be caused by a low battery voltage, also saw this on my XC70 when my battery started to fail especially on a cold morning on first start, but once the engine was warm further starts did not always cause the error.

After I replaced the battery I have not had the problem.

A fully charged battery should be giving 12.7volts.

Anything less than 12volts after charging means the battery must be replaced.

Thank you all

I have had the battery tested and it came back clear, 12.5 volts.

DEM and abs came back no faults,

I have been advised to look under the scuttle panel as there is two large wireing harnesses that can allow ingress of water into the top on the CEM unit, so currently trying to remove the wiper arms off to check for corrosion.

Last two days it's been raining and both days the fault came back straight away, however after driving for a 15 mins the fault cleared.

I am out of ideas where to look for the fault. Has anyone else have similar problems