2006 XC90 issues

[ratchet27]

Hello

I recently acquired a 2006 XC90 with a 4.4L V8 AWD. Around 155k.

The car drives great and had no issues the first several hundred miles.

Then one day (a few days after some rain) it was a bit hard to start (after driving 20-30 miles) and started and died. Fired back up with no issues. No check engine lights or anything. The drove 20-30 miles home without issue.

The next morning I went out to go to work and it started and died and would not restart. At that time I received a brake failure stop safely light and the car would do nothing.

Luckily, I had another vehicle to drive to work. I tried starting it several times over the next couple of days and got the same result. I have a nice OBDII and ran a scan.

1A5F, 1A61, 1A62, E003 and among others. I was able to clear some other but those remained.

I started doing some research and fear that at some point the CEM may have been wet or is still getting wet. The fuses in the fuse box, on the side of the drives side dash, are all corroded. I took each one out and cleaned them (will replace them all soon).

I've checked the drains for the sunroof and they seem to be rather clear. I checked under the carpet on the driver's side and it was dry.

I tried starting the car today (been at least 5-6 days since it wouldn't start) and the car fired right up. The only light is an SRS airbag light. I haven't run a scanner on it yet.

So, maybe the CEM dried out enough for things to work? I'll be tearing into the plenum soon to see how that looks. I also looked at a few fuses on the CEM and they are also corroded. Thoughts? Should I replace the CEM? Too soon to tell?

Also, as of tonight, I could hear some sort of spark/arch coming from underneath the hood. I waited until dark and crawled under the car. I could see it as it's rather regular (maybe every 5-6 seconds normally), but couldn't get a good enough eye on it to tell where it's coming from. I'll have to pull the passenger front wheel and inner fender cover to get a better look. Has anyone ever had this problem before?

Lastly, there is some sort of undefined noise coming from underneath the hood as well. I think it sounds rather electrical (not a consistent hum) as well. I'm having a hard time isolating it, but I think it's near the back of the engine near the firewall closer to the passenger side. I'll try to get a video or some audio.

Sorry for the long post. I really like how the car runs and drives. So, hopefully, I can get these gremlins ironed out.

Any help would be appreciated.

Thanks

[mrbrian200]

Grounding issue most likely. Aggravated when things get wet is typical. 1. main battery ground at the firewall underneath the car LH side. 2. main engine ground wire between the front of the engine to the subframe near the bottom of the radiator left center. 3. braided ground strap between the cylinder head to the RH inside fender.

One thing I'm not sure about is where the subframe grounds to the chassis to complete the ground circuit from the engine back to the main battery negative cable at the firewall. The subframe mount bolts are isolated by rubber in the mounts. That might be what you're seeing arching under the vehicle RH lower side- something loose or corroded between the subframe and chassis that needs a solid connection to carry electrical current.

[oragex]

Have you looked at the cables to the alternator?

Also, for the non start issue and brake message, maybe check see if the DEM has corrosion inside
https://www.volvoforums.org.uk/archive/ ... 00774.html
http://volvospeed.com/vs_forum/topic/14 ... ms-solved/

May as well ask kindly a Volvo dealer if they have an history of repairs with you car. You may find the previous owner has tried/replaced several things trying to figure out this issue. May give you some ideas (just stay away from Volvo, they will replace parts at guess with no results other than a couple of grands less in your pockets, very common)

[ratchet27]

Thanks for the replies so far. I'll hopefully get into it a bit more tomorrow or the next day.

[scot850]

Is the CEM on a V8 under the drivers' seat? I know on a 06 2.5T I looked at it was under the passenger seat. They are know for water leaking into the passenger footwell and soaking the CEM. Can't recall where the water comes in from, but check the drains in the bulkhead are clear.

Neil.

[oragex]

Just found this topic, although the issue is rather with the engine shutting off while driving. Still, points to the CEM

https://www.volvoforums.org.uk/showthread.php?t=128645