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2004 S80 - Electrical system shuts off while driving

Help, Advice, Owners' Discussion and DIY Tutorials on the Volvo S80 model. Sometimes called an "executive car", the S80 was and continues to be Volvo's top-of-the-line passenger car.
dejongmc
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2004 S80 - Electrical system shuts off while driving

Post by dejongmc » Mon Jun 18, 2018 8:33 pm

Here is my intermittent issue: While driving the whole electrical system shuts off for a second or 2, and come back on.
When this happens you can hear some clicks in the dashboard, and the doors will automatically close.
After this happens there is a message on the dashboard saying "Rear left door open', while it is closed.
I had this happen while driving, or idling. When driving, the system will come back up. When idling I have to restart the car.

I already replaced the battery for this reason, but issue still persist. The battery is charged at least 80%.

Any suggestions what it could be or where to look? Such a weird experience if it happens.
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Re: 2004 S80 - Electrical system shuts off while driving

Post by oragex » Wed Jun 27, 2018 9:14 am

Not an easy one. Try also on other forums ( http://forums.swedespeed.com for example)

An honest, independent Volvo specialist may be willing to take the time and properly check the car for the electrical issue, some advertise on craigslist or may find a garage on local.google.com

There have been issues with water leaking over the CEM, but there may as well be other things, maybe a faulty REM ? (google up).

Really needs be carefully tested, not just replace parts

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Re: 2004 S80 - Electrical system shuts off while driving

Post by boosted70 » Wed Jun 27, 2018 9:59 am

I have heard of the engine compartment getting too hot and will somehow affect the ECU

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Re: 2004 S80 - Electrical system shuts off while driving

Post by ndphotonl » Wed Jun 27, 2018 1:14 pm

Does it cut out or is it purely electrical?
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Re: 2004 S80 - Electrical system shuts off while driving

Post by mrbrian200 » Wed Jun 27, 2018 2:23 pm

ndphotonl wrote:
Wed Jun 27, 2018 1:14 pm
Does it cut out or is it purely electrical?
If the engine stops running while driving it won't recover on it's own without using the starter, AT engaged or not. As theresabarnes in effect stated, when it happens on the highway it is not necessary to put the trans in neutral or come to a stop and restart the engine. But apparently at idle there's a 'hiccup' that the ECU can't recover from before RPMs drop to zero (requiring a restart). The hiccup likely occurs at higher RPMs/while driving, however, at higher rpms the ECU is able to recover before engine rotation stops.

Educated theory: when the CEM goes off line while driving (and CAN-DATA communication ceases) the ECU takes an instant to switch to an alternate standalone/failsafe mode of operation.

I think there's enough anecdotal information presented to conclude that the CEM is either going off line, or, something on the network is intermittently corrupting the data stream. Figuring out what/why is the tricky part.

This is possibly one of those cases where reading off the DTCs may or may not be of much help. There are likely multiple DTCs stored. Most or all of which may be triggered as a domino effect.

2nd edit: Keep in mind the MY04s are known for a higher rate of CEM failures. But it's too soon to make that conclusion with the information we have so far. A couple more questions might help to somewhat zero in toward or away from this:

1. does the problem ever occur when the car is cold/short drives, or primarily on longer drives? If the answer is 'usually/only on longer drives', then 'classic CEM failure' bumps higher as a potential to be verified through further testing before concluding the CEM is bad. Refer to xemodex instructions "DIM/CEM and Low Speed CAN Diagnostic Flow Chart" here: https://xemodex.com/us/diagnostic-flow-charts/

2. Have you ever experienced an intermittent no start condition after the vehicle has been sitting for awhile/interior is 'cool'? If the answer is "Yes, occasionally the car refuses to start on the first try", then it's likely something else, and you've got a pretty big can of worms to sort, I'm afraid.

dejongmc
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Re: 2004 S80 - Electrical system shuts off while driving

Post by dejongmc » Wed Jun 27, 2018 6:42 pm

I never have starting problems with this car. The electrical shutoff for a second or 2 happened while driving, but it also happened while idling the car in traffic. If it happened during idling I was able to start the car right away.
It happens once in a while, and I cannot find an specific weather condition this occurs. I'm in Houston TX, so yes it gets hot, and sometimes very wet, but there is no pattern. It really happens randomly.
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Re: 2004 S80 - Electrical system shuts off while driving

Post by mrbrian200 » Wed Jun 27, 2018 11:32 pm

First you'll want to rule out potential flaky power or ground connections to the main modules.

With the battery disconnected check through and tighten all the connections that originate from the smaller red wire that bolts onto the large battery positive terminal back in the trunk. That wire goes to a small fuse box near the battery. Inside that box you'll find fuseable links all held in place by small hex nuts. Make sure every one of those little bolts are nice and snug. One of the wires that exits that little fuse box leads to the REM, follow that wire and make sure that the bolt that holds it to the REM is also snug. Then follow the other wires as they run toward the front of the car, near the REM, sort underneath in front of it there will be 2 or 4 larger plugs, red wires surrounded by foam tape. Disconnect/reconnect those plugs to make sure they are fully seated. Under the dash on the lower part of the CEM, you'll find a plug with two larger red wires (these are two of the wires that originate from that little fuse box back in the trunk). Wiggle and push on that plug to make sure it is fully seated also.

CEM grounds: remove the plastic trim around the front of the drivers footwell area at the door. Underneath that trim between the fuse panel and the door opening you'll find several ground wires attached to the body of the car with small bolts. Make sure they are good and tight. If you see any sign of corrosion on these wires/bolts/terminals/body where they attach, repair or relocate the grounds as necessary until you are 100% certain that they are getting a good solid ground connection.

Back in the trunk, look for the ground connection between the REM and the chassis. It sticks out of one of the wire looms and attaches down lower where it's hard to spot. Same as the grounds up front, tighten the little bolt or screw that holds the wire to the body of the car while inspecting for rust or corrosion and repair as necessary.

Now, the main battery negative cable where it attaches in the engine compartment is also known to get flaky as these vehicles age. It's underneath the car behind the front left wheel about where you'd rest your left foot while driving, except on the outside at the bottom of the engine compartment.
This one is sort of a b-something. Try clean the ring terminal and re-tighten the bolt. However issues with this cable are typically due to rot/corrosion: the heavy wire rots from the inside out. It may look OK at a glance, but that doesn't mean anything. There is a way to replace the terminal end - if the rot hasn't progressed up into the cable more than a couple inches. I'd recommend having an experienced mechanic do that if necessary. Most people won't have a crimp tool large enough to properly crimp the new terminal end onto the wire or know a proper way to seal it up so that moisture doesn't wick up into the copper wire causing another round of rot. The terminal end is available from Volvo as a spare part. Don't use some cheap ring terminal from the auto parts or hardware store. They can get hot, rust, melt, or possibly even cause a fire. If the wire has rotted more than a couple inches back from the end (the only way to determine is to cut off the existing terminal, strip back the insulation and look at it), there won't be enough length left to reattach the cable where it belongs. In which case the entire cable all the way back to the battery will need to be replaced. If after performing the above checks on the power/grounds the issue persists, if you're unsure about the main negative battery cable, a roundabout way to see if the main battery negative cable might be the culprit is to attach a heavy jumper cable between the battery negative terminal and the chassis back in the trunk. If the negative cable is 'flaky', the jumper cable provides sort of a 'heart bypass' and should prevent the issue from occurring while the jumper cable remains attached. Clamp the jumper cable on top of the existing negative cable terminal leaving it attached to the battery and be careful that the jumper cable/clamp is positioned, taped, or secured with cable ties in such a way that no part of it can get near the positive cables/+battery terminal to create a dead short.

If none of that makes a difference you're probably either dealing with CANBUS data corruption (might be a CEM fault or another module that's connected to the network, or water has intruded down into the CEM from the windscreen cowl/wiper motor area.

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Re: 2004 S80 - Electrical system shuts off while driving

Post by dejongmc » Thu Jun 28, 2018 2:18 pm

Thanks mrbrian200 for all the details.
I will make time this weekend to trace all wires.

Where exactly are the REM and CEM located?
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Re: 2004 S80 - Electrical system shuts off while driving

Post by mrbrian200 » Thu Jun 28, 2018 2:55 pm

REM is in the trunk on the left side behind the wheel well. You cant miss it - fuses and relays galore. Bottom part of the CEM is right above your foot while driving. Remove the lower plastic shroud right above your feet, you cant miss it: all sorts of fuses and relays plugged into it. I would make sure all of those are seated fully also. It's not out of the question that one of those relays might be flaky, however, I don't know what they all do. On 05s and later the relays are all inside the thing soldered to the board. 04 and before they're plug-in/replaceable.

dejongmc
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Re: 2004 S80 - Electrical system shuts off while driving

Post by dejongmc » Mon Sep 03, 2018 6:46 pm

Hello,
For the last 2 months I have been trouble shooting my issue and I think I solved it. So let me give back my experience and resolution to our Volvo community for this issue.

'mrbrain200' pointed me in the right direction of the CEM, and apparently that module caused the problem. I contacted Xemodex (www.xemodex.com) and explained them my car symptoms and everything pointed to a faulty or corrupt CEM. Apparently a well known issue with 2004 S80 series (and other 2004 models). So I shipped them my CEM (overnight shipping) and received an upgraded and reprogrammed one back the next day, and now the issue with the electrical system shutting off intermittent is solved.
I had other issues with the new CEM at first, but Xemodex helped me troubleshoot and the CEM was replaced under warranty, but their knowledge and service is excellent.

After I installed the second CEM I had a CEL light, and that was caused by two faulty replays that you have to replace on the CEM. Xemodex helped me troubleshoot all the time and looks like all issues are now resolved.
Luckily we have several cars so had time to work on this, but at the end this would have cost me a fortune at the dealership or any other place who is able to replace CEMs or fix these kind of issues.

Hope this post will help others with similar 'weird electrical' issues.
Let me know if you have any question, I learned a lot about CEM's and Xemodex.
1997 850 NA Wagon - 261,000 miles - Is no longer
2004 V70 NA Wagon - Saved my life
2004 S80

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