Hallo guys
I recently had a problem on my Volvo v40 with not working headlight (high beam and position light works) on the front passenger's side. After reading a few forums, I figured out that the problem would be with CEM. I also have a person who can sell me a working CEM. My question is, will i need some coding after the replacement or will it work automatically ?
thank you for the answers...

 

The CEM for a 99-early 04 sv40 is plug and play. No "coding" or download needed to make it work, and Headlamp relay failure is a known failure. Usually the right headlamp stops working first.

 

Is that true? I mean, I've heard/(mis)understood that mileage is stored in CEM and somewhere else and if their values differ (i.e. replacing CEM) then there would be a warning light of some sorts..? Something from the old CEM needed to be transfered to new CEM?

Is that absolute bull?

 

The mileage is not stored in the CEM. It is stored in the ECU and on the instrument cluster(DIM). Whatever is on the cluster will always show regardless of what the ECU says the mileage is. However, there will be a code stored internally that the mileage changed.

As far as the "coding" I do not know. I know at least 04-09 the CEM would need info transferred by a company like XeMoDeX, but the CEM in 99-04 was built differently.

EDIT: I realized hoonk said it doesn't need coding, I would trust that answer.

 

You could ask these guys - they fix them for a living and should know (Yes all 00+ volvo CEMs are coded to the VIN Other than the 00-04 sv40 to the best of my knowledge)

https://xemodex.com/us/product/centr...epair-service/

 

Thanks a lot for the answer. I've got it all wrong then. Changing DIM (dashboard..?) will result in new mileage, but code will be stored about the change in mileage? How can that code be checked?

 

When scanning the car using VIDA it will show up, I forget under which module. I assume ECU, but I am not 100%. I also do not know if it is a perm code or not. I replaced the DIM in my 06 S60 and had the code come up. I have cleared codes afterwards while troubleshooting something else, but I do not remember if it came back. It's more of a notification than anything else. You will not see this code with a generic scanner.

This also depends on the year I would assume. My car was from post-facelift (04-09). Pre 04 may be different.

 

I don't know, have no experience with a DIM in a 99-04 sv40.

 

Thanks for both of you. I probably won't bother Xemodex unless I'm going to use their service. That feels a bit weird to me if mileage could be altered just by changing dashboard (is dashboard and DIM even same thing?). Unless I've misunderstood something once again, then it's really easy to fake lower mileage? Does Dingus1 have any experience/knowledge on this?

 

It is unlawful to lie about the mileage on a car. That's why there is a checkbox on the title for when the shown mileage doesn't match the actual mileage. When you say dashboard, I assume you mean the instrument panel (where the rpm and speedo is), then yes. DIM is just the volvo abbreviation. (driver information module). Like when I swapped mine on my old car, I checked the box that the mileage was inaccurate and informed the buyer of what the real mileage is. In my case it was only off about 2k miles.

That being said, like hoonk, I have no experience with your specific car. Only 05-09 S60. The S40 is a bit different all around compared to the other members of the volvo family.

 

You can safely swap out the CEM on a Gen 1 (its located right above the hood release lever). No programming required. I bought a used CEM for $65 and that solved my problem for my 2000 S40. There was no impact/relationship on the odometer as other posters have noted.

 

One last question (unless there's more hmmh): I have automatic transmission (V40, 2003 Classic, it seems that I didn't actually specify my car - still gen1 so every reply was valid!) and shifts from 1st to 2nd and 2nd to 3rd are somewhat violent. I've read that it is or has a very high chance of being a CEM related issue. My headlights and parks are all over the place, so CEM absolutely has some issues. Could that be fixed by A) replacing faulty relays B) replacing the whole CEM? I mean, if CEM could indeed be obtained with 65$ then it's absolutely easier and smarter to replace the whole thing. Unfortunately enough cheapest CEM in these parts of the world is about 180 euros - and that's from junkyards that don't give any guarantees that they will actually work.

OH, one more thing that could be related to those violent gear changes. I'm not sure about the words but I'll hope I express myself somewhat clearly.. V40, 2003 Classic should have fuel injection system, right? Engine is running like it has carburator(sp). CEM related or something else? Or it actually has a carburator..??

 

Your transmission shifting problems have nothing to do with the CEM. Your car uses the same aw 50/51 transmission as many other Volvos - 01-07 svsc60,70,80 with the 5 cyl engine. The same trans is also used by many other manufacturers and all have the same problems. One easily solved common problem is the wrong fluid is installed. The correct fluid is essential for smooth operation. Google "volvo slam shifts" for info on common problems and solutions.

 

Newish member with few posts doesn't probably carry much of credibility, but for what it is worth: replacing CEM absolutely had an impact to shifting. It's OK now.

Driving lights are now OK too, BUT there was one slight problem with new (used) CEM. Rearwindow wiper doesn't work anymore, so is the only 2 ways to fix it to a) try another CEM b) replace the faulty relay?

 

You disconnected your battery to replace the CEM, so the car reset it's drivetrain memory similar to clearing any CELs. This could be why your car seems okay now, give it a few days and see if anything has changed. I hope, for your sake, nothing goes back to being bad, but just my thought.

 

Unfortunately enough, it seems that you were some what right. I don't know if it's as slammy as it was before, but it certainly took a step back. I guess though, that excluded wrong fluid as being in fault or do you agree? If it works for couple of days, can the wrong fluid be the reason for this? If not, could or even WOULD new software/programming help or is it something more serious?

 

Software will not help. The correct fluid might help. If you know the wrong fluid was installed you should flush the system or at least do several drain and refills. (with the correct fluid, the toyota type IV is the correct fluid and is an economical choice - compared to Volvo branded fluid. ) Google volvo slam shift for complaints, ideas, solutions.

 

Note that these cars also tend to get corrosion on the connectors to the modules. On my s40, the cure for shifting issues was to remove the TCM, clean the contacts and reinstall.

 

I don't know if I should start my own thread of "Multiple problems" already, buuut..

I did google slam shift, hard shift, rough shift and so on, but I didn't get much out of it (maybe it was just me). Wrong fluid was one of reasons, but software was also mentioned as a fault/fix. Actually to be blunt, the possible faults were all over the place: fluid, software, struts, transmission itself, sensor (I guess some kind of temperature sensors). Well, to correct myself, I got too much out of it.

Anyway, my train of thought was that if it actually works for 3-4 days then it can't be wrong fluid because you know - it works for a while. Software I guess could go apes*** on it's own - or at least more so than a fluid?? Anyway, I guess I could try to replace fluid too, but just wanted to make sure that my thought process hasn't got some flaws here.

This, I think, has more potential, because... I tried to google TCM's location, and got something that "TCM drains battery" and so on. I don't know if this is linked because but I switched battery a while ago (maybe 6 months or so) and I'm having some kind of blue corrosion-foam-thingy on my plus terminal all the time. I don't know if slam shifting has been 6 months already, but quite a long time. Anyway, long story short: could it be a battery-switch-broken TCM indeed that is causing both the hard shifts and overcharging (seems to be the reason for plus terminal's foam-thing)?

 

[QUOTE=DerReskator;512372 Software I guess could go apes*** on it's own - or at least more so than a fluid?? [/QUOTE]

Software does not change after you drive. The transmission "adaptation" does. When you replace a transmission "adaptation" is required to teach the control module how it should shift the new trans (in as quick a manner as possible). And as you normally drive the Trans control unit adapts constantly to give you the best shift quality. If you still have poor shifting, it's because there is a mechanical problem. So new software (costing a few hundred dollars using a VIDA subscription) will not fix anything. Poor shifting could be fluid flow is not correct due to wrong or degraded fluid. That can change with fluid temperature. Could be fluid flow due to sticking solenoids (common) or a worn valve body. That can change due to transmission temp. Worn components = larger clearances when hot = poor fluid control = bad shifts. Could be more internal with the transmission - clutch packs can stick. Worst example case is car is in 2nd, solenoid says shift to 3rd so solenoid a releases 2nd gear clutch and solenoid b applies 3rd gear clutch - except the 2nd gear clutch is slow to release (maybe due to fluid not slippery enough when hot) - then the trans is momentarily in 2 gears at once and tears itself apart a little bit every time that happens.

Here's the beginning of the adaptation sequence. Takes about 45 minutes and can help with shifting - but not if there is an underlying mechanical problem, the shift problem will just stay or come back - because the best shift possible is already happening.

Also below is where your TCM is - if you are curious and want to check connections.