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Discussion Starter #1
Hey folks,

(Feel free to redirect me if this has been addressed in another thread - my searching didn't find anything).

While accelerating from a red light, my 2006 s40 lost all electric power. No dome lights, no dash lights, trunk inoperable, no hazards, key stuck in ignition, the whole 9 yards. Acting as though there is no battery installed.

I believe the battery to be fine. Haven't put a meter to it yet (waiting for the tow truck to bring it home) but it had given no indications of impending failure.

I tried a jump start and it still didn't even flicker. Left battery disconnected for 30 minutes to allow modules to reset, still no change.

FWIW it had been idling in 105+F heat at a drive-thru window just before the failure, in case there are any heat-sensitive electrical components that may have taken issue with those conditions.

The only idea I have is the ignition switch - the car was displaying weird electrical issues a few months ago (jumping tach and odd error messages on startup) but they only lasted a couple days and then all has been normal since. But I can't think of anything besides the ignition switch that would control ALL electrical power - a flip through the manual didn't lead me to any master-type fuse that would disable everything.

I hate to throw a couple hundred bucks at the switch if I'm missing something else. Is there a test procedure for the ignition switch, or any others ideas I'm overlooking? I'm still fairly new to this car and, while willing to get my hands dirty, I'm also willing to admit that I might be missing something stupid :confused:.

Thanks in advance for any insight - I'll update once I can get a MM on the battery to confirm the charge.

Ben
 

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Sounds like a CEM failure but I am a shade tree and not a pro. Might want to let someone else chime in here first. If I read this thread correctly you have no power at all. Not even a dome light?
 

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Discussion Starter #3
Correct, not even a dome light - cannot find a single electrical component that is functioning. No power locks, no hazards, nada. It was so abrupt - fine one second, completely dead the next, with no leadup whatsoever.
 

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I'll bet you've got a heater core leak that fried your cem / body module. Check your cem under the glove box.


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Discussion Starter #5
I'll pull out the CEM tomorrow and see if I can see anything. If it's fried would I expect visible damage, or is there some test I should perform? I sure don't notice any moisture in the footwell.

Also, as expected the battery reads just fine. Hurts to rule out simple (and cheap) solutions.....
 

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Yep. CEM. We've experienced this a couple of times. Fortunately it was just a bad, intermittent connection in one of the connectors and went away once I cleaned all the contacts. The car was dead as a dodo when it occurred and I suspected something much worse. The CEM has been acting up every now and then, especially on cold and wet weather, but problems have been rare since I opened it up, reflowed everything with an SMD soldering station, sanded all connector pins and hosed it with PRF 7-78. The workmanship and design of CEM are unimpressive to say the least, and the quality of wiring and connectors isn't much better. Be sure to check (open, sand, grease and tighten) the grounding points on both front doorsills, too. They're prone to corrosion.
 

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Wow- another weak link in our Volvo's? I was thinking, is there anyway to wrap the CEM in plastic and seal it maybe so that if/when a heater core goes, it doesn't screw up the electronics?
Another weak link is the absence of a level sensors in our (coolant) expansion tanks. I'm working on a solution for that by actually installing one.
But, this MoFo (or is it FoMoCo?) doing is unforgivable and could have been avoided with proper design. :mad:
 

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I tried to wrap my cem with plastic but it's just too tight of a fit.

My footwell was completely dry, for a while. But underneath the carpet was about a gallon of coolant. Point is, you could have a small o ring leak and the cem is directly in the path of flow. When I pulled mine it had burn marks from where it had shorts out though I have also heard about bad connections causing an issue.


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Discussion Starter #9
Yikes. Fingers crossed for a bad connection - I'll pull it out today, sand the pins, and check for evidence of shorting. From my reading, it appears that there is no reprogramming a secondhand unit, but that it would have to be purchased new from dealer and programmed?
 

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I'll pull it out today, sand the pins, and check for evidence of shorting.
If that fixes the problem, remember to use a generous amount of battery pole grease in the connectors/pins to reduce the probability of them corroding again. They're dry from the factory hence in contact with air, which will cause problems whenever there's humidity present. That may even limit the damage further down the road when (I don't say if) your heater core seals go and shower the CEM with coolant.
 

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Discussion Starter #11
I disassembled the unit, found no evidence of shorting, cleaned all the pins, sockets, and fuses, continuity checked grounding points on door sills and under hood, reassembled everything...and I still have a paperweight. Not even any power to the OBDII port to activate my scan tool.

From all the searching I've done the past couple days, I gather a failed CEM to be the only issue that would cause a complete electrical failure (I guess even with an ignition switch failure, there should still be power to some systems?) and that a new CEM must be programmed to the car via VIDA? That being the case, I'm going to bite the bullet and have it towed somewhere tomorrow. Mercdude, I see you're in Northern CA - any wild chance that you're near the East Bay and have any recommendations on a quality shop? I've got some Yelp ideas but always more inclined to trust somebody less random.

Thanks everybody for the insight thus far :/
 

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Before you jump to that I'd test for power at the basic points. Voltmeter between the positive post & chassis point show battery voltage? You know the ground cable & attachment is good. Have you tested for power at the fuses under the hood? Fuses 1-4 (& most others) should see power all the time. These are large fuses that send power on to the CEM, etc.

Diagram is HERE. Check page 9 (Electrical Distribution).
 

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Discussion Starter #13
Failed to mention that I did check the fuses under the hood. 12.73V everywhere. I did not, however, check for power coming INTO the CEM. Thanks a lot for the diagram link - I'll check that before I do anything further.
 

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Having sort of the same issue. It has happened 3 times today. I lose all electrical power in the car; dash, radio hvac, throttle, etc. Only lasts for about 2 seconds then comes back. When it comes back the engine is still running and the radio presets are still stored. Anyone have this before, or any ideas?
 

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Check all Your Grounds Clean etc. , but could be also the Ignition Key switch Going .. Check all the CEM Connections , ECU etc.
I Found some Dirt around ECU Rubber Connection area - Never got inside , but have No Idea how it got there ..( Slow Build Up from Debris - Kicked up into Rain ) While On the Roads .. going State to State .

Amy Mods around that Air Intake system Or Stock ?
 

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Check all Your Grounds Clean etc. , but could be also the Ignition Key switch Going .. Check all the CEM Connections , ECU etc.
I Found some Dirt around ECU Rubber Connection area - Never got inside , but have No Idea how it got there ..( Slow Build Up from Debris - Kicked up into Rain ) While On the Roads .. going State to State .

Amy Mods around that Air Intake system Or Stock ?
Going to check CEM connections and ECU. Intake is stock.
 

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Hi
I’m here to give a thanks to all the people who pointed out the the CEM connectors could be a basic thing to check before going to the repair shop, we’ve encountered a similar problem of total power lose, but, the car starts fine, lights and blinker all working, but no power to the dashboard or the dome, speedometer doesn’t work not the blinker indicator, I was fortunate to find this post, and upon finding the location to the CEN connectors in the driver footwell, I pressure aired the connector then clipped it back in, no go, then I bent over backward to see if there is any other connectors, and there was another, unclipped it, then pressure aired it, clipped it back in, and I get the power is back again, it would of been a joyful moment, if while I’m bent over backwards, in the driver footwell, the chair memory kicked in, trying to adjust it set to my wife’s size, so pulled a quick reach to the adjustment switch and reopened it, to live, yet another day, and thank you guys for the help, may you always find solutions to your problems, and may it be simple and free.
 
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