How to: Volvo C30 S40 V50 C70 CEM Removal and Cleaning

How to remove and clean the Central Electronic Module or CEM for short on a Volvo. This particular car I am working with here is a 2007 Volvo C30 and a similar procedure can also be found on the S40, V50, and C70 models. Dirty connection on the CEM can cause quite a few problems either relating to the security system, ignition, gauges, wipers, power accessories, lighting, safety restraint system, a majority of electrical components in the car. For this car, my radio is experiencing an intermediate operation, especially on more humid days. This problem can also pop up if you’ve had a plugged sunroof drain or left a window open during a rain and water managed to get inside the car. #volvo #volvoc30 #volvos40

Tools/Supplies Needed:
-3/8” drive ratchet
-3/8” drive 3” extension
-10mm 3/8” drive socket
-electrical contact cleaner
-electrical contact protectant
-clean rags
-electric brushes

Procedure:
-disconnect the battery using a 10mm socket with ratchet and 3” extension, remove the negative terminal
-the CEM is located under the dashboard
-remove the fabric cover which has two plastic clips, by just push the center in with your finger which will disconnect the clip
-to pop down there are two twist clips which need to be disconnect and then the panel can be dropped down
-there will be various electrical connectors both on the top and bottom which need to be disconnected
-for the smaller rectangular connectors, they have a lever which needs to be pulled back, this will lift the connector out of it’s location and then it’s disconnected
-for the largest connectors, there are tangs on each side which needs to be depress and they can then be pulled back
-there will also be a couple black connectors that has a tang which needs to be depress and they can be pulled straight out
-pull back the module and pull up to completely remove
-there will be similar lever style electrical connectors on the bottom that need to be disconnected too
-once fully done, the module can then be removed
-for cleaning, we’ll be using contact cleaner, something which helps dissolve corrosion
-first using a brush to remove any loose debris, try to remove as much as possible
-moving onto the contact cleaner, spray the area, allow it to soak and then agitate the surface using the bush
-wash off the area again using more contact cleaner
-repeat if needed, with some contact cleaners you may need to let the solution soak over night to remove any serious corrosion
-while the connections are free of corrosion, I’ll still go over everything just to be safe
-using the procedure, you can spray down the contacts, agitate the surface using the brush if needed, then wash away the area again with contact cleaner
-I decided to remove both electrical components to clean those areas as well
-depending on the contact cleaner, it may evaporate on it’s own either slowly or fast or you may need to dry the area off using compressed air or a clean cloth
-moving back to the car, I have laid down a shop coat to prevent any overspray from the contact cleaner
-remove any loose debris, this time you can use a toothbrush
-spray the connector using the contact cleaner and agitate using the toothbrush
-wash away any debris, then allow it to dry
-move onto the other connectors using the same process
-I left the module for a couple hours to dry and now I’ll be using an electronic terminal protectant which also helps promote connectivity
-using the supplied brush, apply the solution to the male side of the connectors
-clip the module back into it’s location, each wire has a specific shape so they cannot be mixed up
-push the module back into it’s pivot location
-I left the car sit over night just to be safe so the cleaner’s residue has a chance to dry out or evaporate
-push the module back up and screw in the retaining fasteners
-for the fabric cover, the center of the clips must be pushed out so they’re disengaged
-push the clips back into place, then push the centers in so they’re locked into place

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[richardlynn]

You have just saved me £1, 000 which a dealer quoted me due to a ignition issue (over starting). Bought a £4 can of the solvent, cleaned a couple of the green connectors and put it back together whilst in some questionable positions...

I can't thank you enough.

[jubilee]

You are a legend.
My s40 went nuts every warning on dash and car wouldnt start.

Checked under and brown connector not plugged in.
Plugged back in and its perfect again.

Thank you so much

[TobyBartley]

Thank you so much! I believe this is the culprit, I've had all sorts of weird electrical gremlins and following your tutorial was able to pull it out and noticed corrosion, just need to get some contact cleaner and give it a go. You are a lifesaver!!

[dannykyro]

Likely saved me thousands by doing this quick fix, thank you! My 2005 Volvo t5 v50 AWD suddenly started having multiple electrical problems: wipers stuck on, no turn signals, loss of window function, loss of lock function, alarm set off while opening hood, and gas guage failure. I found corrosion at the same spot that was in the video but his looked more severe. Cleaned with no contact cleaner safe for plastic, nylon brush, blew it out like a Nintendo cartridge and presto! Everything works again! I will note that I went pretty light on the cleaner, dried for only a couple minutes and skipped the electrical contact solution. Still worked for me.

[rich]

This is awesome video. I had 15 volvo specific codes on my 2006 S40 after having recent acceleration problems. Last two years, I was getting intermittent "engine system service urgent" message. It was on most of the time in last few days. I cleaned as shown in the video along with reinserting all the fuses plus cleaned grounds on the passenger side of engine compartment and down by the passenger door. I put it together, message was gone. I still had the codes and cleared them using an ES610 scanner. I took it for a drive and the old acceleration was back. Thank you so much, this demonstration really helped me .

[QuentinPiganeau]

Thank you very much for your tutorial!


My volvo c30 was completely crazy: dashboard that went off randomly, lights abs, airbag, electric paralysis on the right side (window, central locking).


Everything disappeared with just a blow of elbow oil, which would have cost me 1500 € to the garage.


Quentin from Bordeaux, France.

[bencroucher]

Massive thank you for this video! My 04 s40 t5 threw a fit after a stall/quick restart. Wipers on, windows stuck down, interior lights, slight loss of power, no central locking, fuel gauge off. Anti skid and sas airbag warnings on dash. Followed your video step by step apart from the last fluid you applied. Car is sorted 😎👌

[kurtmarucci]

Excellent tutorial. I was planning on doing this to my 2011 S40 T5 which has assorted intermittent electrical problems (I think related to the fact I live in a humid climate). And, I was just going to "wing it", being an EE. But, your tutorial is going to make the process so much easier. I can't thank you enough.

[nadaypuesnada]

Thanks a million for this video. I have very little experience "working on" cars, and the detail you provided, along with the good camera angles, gave me all the information I needed to complete the job.

[MrGman]

Thanks for the information. Very useful. I would not have had the confidence to do this without it. I followed all of the procedure. I have a 2005 V50 car and a 2005 CEM, as it has a date on it. After removing the CEM, I could not see any evidence of either corrosion or dirt. It all looked very clean. Nonetheless, I sprayed each connector, male & female and cleaned with brushes. I will have to wait and see if it fixes my problem which is indicating the CEM is the source of various issues! Fingers crossed. If this doesn't work, I will try a reconditioned I did read elsewhere that sometimes the welds on the motherboard are a source of problems??? I think I prefer older cars which have more basic electrics!

[CG-osit]

Really excellent video. Like others I was getting numerous alarming messages including the following "engine system service urgent", "Brake failure stop safely", as well as having the airbag light on, window wipers going off on their own and the windows themselves not working. Also the car refused to start after the "engine system service urgent" appeared! Anyway, a local auto electric mechanic told me that the CEM unit on the Volvo S40 (my car) is prone to cause a multitude of issues including mine. This being due to corrosion on the CEMs contacts. He also noted that there was a voltage drop on my car. Anyway I cleaned the CEM with WD40 Contact Cleaner, reassembled obviously!, now the car is going like a rocket!



Many thanks for this great guide. Probably saved me a lot of money.

[kurwamac]

My CEM was looking clean but I had some problems. Cleaning it like you showed help me get rid of all the issues. My Volvo V50 is going further :) Thank you

[heatherhehn]

Really glad that I found your do-it-yourself video for module issues. I had an interlock device installed 3 years ago 4 years ago actually and I have had issues after it was installed and coincidentally my sunroof had to be fixed due to the tubes in it leaking onto the floor causing pretty significant water accumulation. So I'm not sure if those two circumstances affected the module or if one particular issue was the culprit. What occurs when I drive my car especially when it engages into turbo I will receive a notification on my dash that says anti-skid service required and then my car will go into safety mode taking it out of drive gear and if I drive it for a while it will suddenly pop abruptly into drive and if I didn't continue driving it and needed to stop and put it in park before it has a chance to pop back into gear it will go into immobilization mode locking my key thus leaving my battery on. So one mechanic told me to disconnect what appears to be some type of module in the engine that's wiping out the memory of the cars notification system I guess giving it temporary amnesia wiping out that memory that has a issue and then I'm able to restart it get my key out etc. Volvo dealership had it for a month and said they're getting a miscommunication error but they can't figure out out of the three modules where it's originating from because it doesn't misbehave when it's on the diagnostic itself. So I've been driving it like this for 2 years minimally. I've been using my deceased sisters Passat and it's alternator just went to put on me so I'm back to the Volvo drill that I have to endure randomly it only happens 5-7times a month when driven regularly. And as it is a 2004 S40 I am a single mom and a budget and I can't even fathom spending the money Volvo wants to charge me for a brand new ECM/ECU Module and a reprogramming fee wiping out my nest egg $$
for a car that has a Kelly Blue book value if $2, 400.00. So with that said, I'm going to try doing exactly what you so beautifully demonstrated with the best clarity I have seen on any do it yourself tutorial that is available . Thanking you in advance for taking the time to video the process and making it so easy to understand for a person who is somewhat mechanical at least I think I'm really good mechanically but not a professional auto mechanic. Single moms have to do what they have to do and stretch a dollar pretty far. Thank you again I'll let you know if it works!!

[kashinokikendo]

Brilliant video, worked for me and I know nothing about car maintenance.

[liesla.]

This is a fabulous tutorial- I was having issues with my 2005 S40 and was able to get it going smoothly again. Thanks so much

[MK-tbex]

Awesome tutorial video! Concise, brief and on point! Your channel is the only channel i receive notifications as new ones upload. Keep them coming. Mad respect! Ty.

[libertymunkombwe]

Fantastic tutorial. Clearly you know your staff.

[metriczeppelin]

'08 S40 T5 w/142K here. Recently purchased. Check engine light comes on, 1st time it was "erratic ignition, " misfire on cyl's 3 and 5. Later came back on and it was cyl 4 misfire. Changed all plugs with new NGK's. Then changed all 5 coil's as suggested. Neither made a difference. Starting cold the engine fast idles with misfires. Goes on fast idle perfectly then drops down to preset idle. Only seems to misfire at stop signs, traffic lights, anywhere I have to actually stop. But upon acceleration the car does fine, lots of power thanks to the turbo. But the low level putt, putt, putt at a stop is annoying. I dropped the CEM under the glovebox and pulled all the plugs and cleaned with an electric spray cleaner. The best news is I didn't make anything worse!! Gotta take those wins when you can. But the low level misfire remains. Just wanted to share this with anyone who may be having similar issues, Good luck to all and a blessed new year.

[blagatz]

Yeah so my right side lowbeam light seems to have an issue. This may be the answer. I’ve replaced the bulb, bought several actually, and no dice. Hope I don’t mess this up. Thanks for your awesome videos, I’ve got a 2007 Volvo s40 and your videos rock!

[sndsergiu]

I appreciate the amount of work you put on explanations from this video. If you don't mind, can you add what kind of electronic terminal protectant did you use? Can you provide a link, please?