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Discussion Starter · #1 ·
okay this is my brothers car. Pretty confident it's the CEM going bad/overheating.

Symptoms: only in stop and go traffic, really hot days.

dash flicker
relays shutter
foglights turn on

4-5 times in a 20 minute period

next: It will do that, and then it will turn off the ABS and give brake failure pull over indicator
At that point the car has to be restarted to restore the brakes

this happens 3-10 times

then it does that and ALL electronics are gone except radio and engine keeps running. Obviously extremely dangerous, talking total electrical blackout minus stereo and somehow the engine still runs.

Restarting the car after letting it cool restores functionality eventually.

So having seen one thread about a similar issue before....it seems the consensus that the CEM has gone kaput. Would you all agree?

So now, what to do about it. It's about $1300+ for a new CEM as volvo has them encoded and crap so you can't use a used one at all. A NEW one has to be programed to the car etc. etc.

now as for replacement and all that

http://xemodex.com/ <--they make ABS modules and not a CEM, but what i'm mainly interested in is they seem to have cracked what ever encryption there is in the system to re-manufacture these parts. Could it be possible to re-program a CEM?

If not, whats the best way to go about replacing it? I hear it has to be gotten at from the firewall forward.

If it's a heat issue, has anyone managed to slap a heatsync/fan on the unit? We've got access to a full C&C capable of custom heatsyncs.

thanks in advance!
 

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I did a write on this a couple of months ago on how mine wasn't properly cooled. It worked for some time, but now I'm having the same problems again and it looks like I'm going to have to bite bullet on this one. I'm checking for any damaged wires to see if anything is shorting out, after that...Its a new CEM. :mad:
 

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Discussion Starter · #4 ·
Nope, alternator and battery check out...if it were the engine would die also.
 

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If you will finish up buying new CEM, please keep the old one & send it to me. I'll cover your shipping costs.
What I am on about is getting my hands on ****ed modules & find the way to make them work again.

Let me know if you like the idea...
 

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Discussion Starter · #6 ·
If you will finish up buying new CEM, please keep the old one & send it to me. I'll cover your shipping costs.
What I am on about is getting my hands on ****ed modules & find the way to make them work again.

Let me know if you like the idea...
Unless you have the volvo equipment and a way of cracking their encryption and then reprogramming the ECU to match the vehicle, sorry.
 

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I'm not talking about SW at this moment, I seriously think that most common faults are HW related. And your case is very clear, a single point failure knocks down whole CEM. It does sound like power supply issue or similar...
Well, we will never know.
 

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Discussion Starter · #8 · (Edited)
Ah, well my brother happens to be a mechanical/electrical engineer so i'm sure he'll look into that.

BIG BIG BIG UPDATE:

called xemodex. First off, they say then CAN reprogram and redo CEM modules, they do it rarely but they can do it.

Now the main thing. THE ECM IS COVERED UNDER THE FEDERAL EMISSIONS EXTENDED WARRANTY!!! Xemodex said this, looked in the paperwork and sure enough it's listed under the volvo warranty. It's an 8 year 80,000 miles warranty.

Volvo will remedy only those non-conformities resulting from failure of certain specified emission control components for which coverage is eight (8) years or 80,000 miles/130,000 kilometers, whichever occurs first. These major components include only the three-way catalytic converter (TWC), engine control module and the on-board diagnostic system (OBD)
 

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Well the car goes in Thursday to start the game with the dealership to prove its the CEM.

Other sites have suggested that idling the car in the parking lot for 30 minutes with the heat on high will provide enough heat to get the CEM to malfunction in intermittent issues like mine and Adale's. I have to demonstrate it to the dealership or generate enough codes that they are convinced the CEM is the cause and will repair under the warranty.

I had the codes pulled at my local independent shop on the Volvo Vida system and reset on Monday before I knew about the emissions warranty coverage (see your manual, the ECU, CEM, OBD, and Cat- Converter are the 4 parts specifically called out as 8yr./80K coverage). 16 codes in all- no hard fault failures of the CEM (typical because when it looses power, it doesn't log the event) so the diagnosis, by nature cannot be a hard diagnosis without empirical testing (removing other modules till only the CEM is left- as done to another car at a Florida dealership).

This last one happened in 19F white-out conditions on I-70 going over a pass. Normally a car turning off at speed or loosing ABS and lights doesn't bother me but in snow-ice, zero-vis and stop and go traffic going over the continental divide- even I am a bit spooked.

@Adale- look at the TMM for the 05-06 R's on the corrosion of the CEM harness and connectors due to moisture seeping into the CEM box. Not sure why 04's were not included. Any techs care to expound on that?

@Zeljko_M - I'm thinking FET or varistor on the logic power (5V/3.3V) for the micro-controller in the CEM. Whats your guess?

All- Note this problem seems most prevalent in 04 R's but is also documented in the great internets in S80's V40's and XC's .
 

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Discussion Starter · #11 ·
^^my brother, if you guys didn't figure that out :p
 

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@Zeljko_M - I'm thinking FET or varistor on the logic power (5V/3.3V) for the micro-controller in the CEM. Whats your guess?

All- Note this problem seems most prevalent in 04 R's but is also documented in the great internets in S80's V40's and XC's .
Most modules use voltage regulators, linear or switched. First thing I would check is their contacts. If linear type regulators are used they can
generate a lot of heat, and in already hot environment they sometimes overheat solder on joints.
If you take a look I'm my haldex rebuild you will se that they have used solder less contacts. It has some benefits, but during time it can get bad contacts.

Use your eyes and look for irregularities if you decide to bust it open.
 

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Discussion Starter · #13 ·
Update: The dealership is trying to claim it's the steering wheel module causing all the issues, no computer proof just a judgement call by the tech. Quite obviously he's full of it.
 

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You should all forgive my overly excitable younger sibling- hey we all have them.

I've had pretty exhaustive conversations with both my independent shop which has pulled codes on the car the past couple of months, the service agent at the dealership where the car is presently (who is a moron) and the actual technician working on the car. There is no clear resolution at present but here is where we are at currently:

0.) I was able to replicate symptoms yesterday by leaving the car idling in the parking lot with heat on maximum for a little over 1Hr. Lots of symptoms including loss of power locks, windows, Gauge Cluster, DMM, power seats, Turns signals, keyless entry, heated seats, emergency signals. The Dome lights came on, I still had power steering, Engine, throttle and brake lights. Wipers also went continuously but at one speed regardless of setting.

1.) Dropped car off at dealership. Tech pulled codes. Lots of codes including, all of which (save for the Steering wheel angle module) were on the Low-speed CAN side of the CEM. This is mostly consistent with my previous two code pull runs, however the individual codes are different each time.

2.) Tech was able to replicate symptoms using above procedure.

3.) At which point he began DiCE diagnostics. As the tech explained to me DiCe is basically a USB dongle equivalent which hooks to the computer and has 3 led's (proper COMM, COMM request but error, Very BAD). My car was blinking the blue, very bad light. At this point he began pulling fuses to modules and when he got to the Steering Wheel Module (SWM) and disconnected it, the system went to the green- Proper COMM/no-fault light. The system reset when he put the fuse for the SWM again.

4.) Tech's team leader independently verified the above.

5.) I have a very long conversation with him going over all the above in detail and we resolve to call Volvo tech help in the morning to see if their diagnosis matches the SWM not the CEM.

The SWM is a roughly $600 module with virtually no labor. The CEM would be covered under the Emissions warranty.

The quandary is simple and unfortunate:

If I pay for the SWM and the problem is solved then only I owe something.

If the tech goes with his diagnosis and I pay to install the SWM and the problem isn't fixed the tech has to eat the cost of the SWM and Volvo will pay for the CEM and I pay nothing.

If the tech is persuaded and installs the CEM under warranty and the problem is not resolved and in fact is the SWM, then I pay for the SWM and the tech pays for the CEM and Volvo pays nothing.

If however he installs the CEM and the problem is solved then I pay nothing, the tech pays nothing, and Volvo pays for the CEM.

Somehow, these all look like losers to me?

What is unfortunate is based on the conversations with all the various techs is that the CAN system in pre-08 models are all series based CAN comm and if any module glitches it can bring down the entire side of the CAN system (there are 2, a low-speed and a high-speed) to the CEM. According to the tech the 08+ models have a self correcting CAN system which can isolate out individual modules or not be affected by 1 module spitting out gibberish. (this sounds like a comm. buffer issue to me).

IF this is true, it would mean that while Adale and I have almost identical symptoms as do several of the other cars that have reported issues, any module on the low-speed side could be the cause (and not the same one at that).

OR, the simple answer is the correct one- that it is the brain that rules them all- the CEM is bad in all these cars and fails on temperature.

I guess we will find out tomorrow. I'm willing to put my money where my mouth is and let them do the SWM. If it fixes it then my car is healthy and I will be content. If it doesn't then I can feel warm and smart and the CEM will get replaced by Volvo at their expense and that I got to stick it to the man (unfortunately this really means screwing over a man (the tech) not 'the man').
 

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Wow...I'm confused more than ever...:confused:
 

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So it went from CEM to maybe the steering wheel module to any module using the low-speed side.... I love my R...:rolleyes:
 

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Well Bodie, good luck tomorrow. I hope everything works out for ya...btw, which fuse is the swm? Might have to go check out mine too....
 

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All,

So after they talked with Volvo my dealership was advised to do the CEM replacement. Seems to have done the trick. Short version Adale, its probably your CEM like we've alway thought. The additional 'test' Volvo had the dealer do was to leave the key in the on position with the engine not running for several hours until faults showed up in the CEM and then pull the codes.

Only problem now is that my daytime running lights don't seem to be working......
 

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When a module is replaced the dealer is supposed to read off all of the "per user" settings and program them to the new one.

The DRL settings are contained within the CEM, so it sounds like they never restored your DRL settings correctly.
 

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All,

So after they talked with Volvo my dealership was advised to do the CEM replacement. Seems to have done the trick. Short version Adale, its probably your CEM like we've alway thought. The additional 'test' Volvo had the dealer do was to leave the key in the on position with the engine not running for several hours until faults showed up in the CEM and then pull the codes.

Only problem now is that my daytime running lights don't seem to be working......
Just sent Volvo a nasty email and will follow up with a nasty call in the morning. Volvo of Tampa quoted me for a part that has warranty....STEALERSHIP! Thanks BODIE
 
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