2004 Volvo S80 AWD Limp mode/ABS/won't start

TCurtis10 · Post by **TCurtis10** » 11 Jul 2015, 18:17

Hi!
I have a 2004 Volvo S80 AWD. Over the past year or so it will intermittently pull some pretty strange problems out on me. Mind you if I don't drive the car for a few days they go away.
One of the problems is I will go to start the car and it will turn over and fully start then just completely die and my check engine light will come on and it will also say the transmission needs service. This seems to happen randomly and if I get out of the car, lock it, remotely set off the alarm, then unlock and try again. It will normally start and drive fine.
Nothing is wrong with my transmission according to the dealership.
Also, when I'm driving occasionally, the car will enter limp mode.
At first, my speedometer and odometer will stop working. My a/c will turn off, my mileage disappears and sometimes it'll continue to drive fine but sometimes after a while (though it occasionally happens immediately) it will no longer shift into higher gears.
most importantly it will say that my abs is offline and "brake failure, stop safely" will appear.
I have taken it to the dealership and they have replaced my abs module. Yet this still continues.
I have also had my a/c fan motor replaced in the past, when it wouldn't turn off even with the car off which drained my battery (so the car has a brand new one) however that problem has been fixed.
Any ideas?!?

Post by **precopster** » 12 Jul 2015, 03:48

The more varied the different intermittent issues are the higher the probability that the CEM is the culprit.

This is primarily because the CEM is the central bus junction point for overall communication in the later (post '99) series of car

Contact XeModex in Canada and speak to a technician there. I think a rebullt CEM will solve all the issues.

Post by **doublebug** » 12 Jul 2015, 05:14

And since it is AWD car another module that can flood is DEM.

TCurtis10 · Post by **TCurtis10** » 12 Jul 2015, 09:54

Thanks so much. I'll have both of those looked in to, though I'm disappointed because last time I went to our Volvo specialist mechanic out here they said all those were checked and working fine and that's why we replaced what we did. I was assured the problem would be fixed and it happens so infrequently, with months in between occurrences, that I always just wondered if it wasn't just a simple bad connection or something since the most frequent issue is with the electronic immobilizer being tripped which I can normally easily fix like I said by setting off the alarm. But I know that relies on the CEM, I was just really hoping that wouldn't be it.

Post by **precopster** » 13 Jul 2015, 06:25

Has anyone tried refitting and clean with contact cleaner all the connector plugs on the CEM (and DEM as Henry mentioned ) in an effort to faultfind this problem? Sometimes throwing time and thought into a problem pays a lot better than swapping parts

TCurtis10 · Post by **TCurtis10** » 13 Jul 2015, 07:59

That will definitely be my first stop before replacing them! Thank you!

Post by **precopster** » 13 Jul 2015, 15:24

Failing the step above you could try heating the CEM/DEM with a hairdryer to simulate a hot environment. Many faults are brought on by heat.

TCurtis10 · Post by **TCurtis10** » 13 Jul 2015, 16:36

I live in Florida and it gets very very hot on a daily basis. But I feel the frequency does increase on particularly hot days or if I've been driving around a lot more than normal. Then again that could just be in my head since I live in fear that it'll act up. I'll check both options out though and update! Thanks so much yall!

volvobro · Post by **volvobro** » 19 Jul 2015, 19:22

any updates? I have the same car as op and I'm having a similar problem. about to refit and clean connector plugs of my CEM/DEM to see if it works.