CEM Acting up??

[AndyV7o]

Hi, as mentioned before I cant use search function as the box disappears every time I attempt to type...
Yesterday I had 'Brake failure, stop immediately' fleetingly illuminate 3 times, one other time it stayed on about a minute or two, nothing wrong with brakes (could be an abs sensor breaking down etc), didnt worry, continued my journey (I did check brakes).
Tonight I could not lock the car. In the end I got back in, started it up, idled 20 secs, turned back off, got out, car locked as normal.
When I recently had a bulb failure it told me so, but the warning was on and off like a disco, dont know if this is usual, but generally such massages stay put until bulb replaced, not come on/off in a random pattern, so now wondering if it could be related.
Could this be Cem problem? Maybe instrument cluster, but I dont think locking is related to that?

Cheers!

[XC90Mk1]

Originally Posted by AndyV7o

Hi, as mentioned before I cant use search function as the box disappears every time I attempt to type...
Yesterday I had 'Brake failure, stop immediately' fleetingly illuminate 3 times, one other time it stayed on about a minute or two, nothing wrong with brakes (could be an abs sensor breaking down etc), didnt worry, continued my journey (I did check brakes).
Tonight I could not lock the car. In the end I got back in, started it up, idled 20 secs, turned back off, got out, car locked as normal.
When I recently had a bulb failure it told me so, but the warning was on and off like a disco, dont know if this is usual, but generally such massages stay put until bulb replaced, not come on/off in a random pattern, so now wondering if it could be related.
Could this be Cem problem? Maybe instrument cluster, but I dont think locking is related to that?

Cheers!

Are you not able to plug a fault code reader in and read the codes? I purchased an Autel reader of Ebay and it is really good, that way you would know what the failure is.

It sounds electrical doesn't it, and mechanically you may be OK but clearly I would not drive it with a brake warning, its really not worth the risk.

[AndyV7o]

The brake warning instances occurred within about 1.5 miles, for the remaining 9 miles home, nothing. Nothing tonight either. There is no permanent fault light illuminated.
It could be as daft as Id just been through a puddle, maybe moisture in a sensor plug.
Im keeping my eye on it.
It was the locking issue tonight that really made me wonder...

I have an obd reader but it doesnt do anything other than engine.
Did just buy an elm27, dunno if that has more capability (to use with torque app) but so far my phone cant find it, Im in discussion with vendor...

[AndyV7o]

So far nothing further to report...
Long ish run tomorrow, see what happens...

[R-P]

CEM failures can be very different in appearance, from what I read.

When I am locked out of the remote-locking system (see what I did there? ), I need to disconnect the battery before it resets itself.

My CEM-problems are clearly temperature related, so if it was hot, that might be a clue it was the CEM.

[AndyV7o]

Cheers.
So far, nothing since, did 200 miles in it yesterday, fine.
Only temp related thing I have is the alarm, it sometimes goes off when in direct blazing-hot sunlight, I then get 'Alarm triggered check car' also 'Alarm system service required' message, which pops-up sporadically anyway, again, usually when hot. Havent got round to pratting with alarm box yet though...

[MWMan]

Like R-P mentioned, my CEM started playing up when it got hot. (Its pretty well boxed in under the dash). Once I had determined it was the CEM causing all of my problems, I fitted a PC cooling fan to the unit itself and another one on the bulkhead to move the air around. I also fitted a switch so that I could turn it on and off as required.

Here is a post from last year when another member was suffering from the same thing. Post #5 has the pdf file showing what I did. https://www.volvoforums.org.uk/showthread.php?t=270209