CEM installing

Whitewagon2 · Jul 6, 2023

CEM question.
2005 XC70
If I order a rebuilt CEM off eBay, would it need to be taken to a local Volvo dealership to be flashed? Looking for the cheapest way possible, as I’d want to install the CEM myself. Just wondering if anyone has any experience with this.
Basically I’m wondering if I’d be able to replace CEM without having to send it off, or be without a car for an extended period of time (my job requires transportation)! Thanks!

vtl · Jul 6, 2023

You need to clone your CEM. That requires reading the dumps out of Renesas M32C and EEPROM and writing them to your donor CEM.

Cheapest is to use a USB-FTDI cable, solder wires to CEM and read/write with m16c-flasher.de software (with caveats...). EEPROM chip you can try to desolder and transfer to the donor, or read the contents with programmer like TL866a.

In case you already have a soldering station, cable and a programmer it is basically free.

hoonk · Jul 6, 2023

Whitewagon2 said:
CEM question.
2005 XC70
If I order a rebuilt CEM off eBay, would it need to be taken to a local Volvo dealership to be flashed? Looking for the cheapest way possible,

I would not count on your Ebay CEM working without jumping through many hoops.

1. As far as I know - the dealer can't program/flash a USED Cem to work in your car (using the only method they have, VIDA)

2. Someone like xemodex can fix or program a used Cem to work in your car. And they are in Canada.

xemodex can fix and return control units in less than 2 days sometimes. I think they work nights!

What's wrong with yours? Why do you want or think you need to replace it?

GRUENDIG · Jul 6, 2023

hoonk said:
I would not count on your Ebay CEM working without jumping through many hoops.

1. As far as I know - the dealer can't program/flash a USED Cem to work in your car (using the only method they have, VIDA)

2. Someone like xemodex can fix or program a used Cem to work in your car. And they are in Canada.

xemodex can fix and return control units in less than 2 days sometimes. I think they work nights!

What's wrong with yours? Why do you want or think you need to replace it?

You pays your money and you takes your chances. - Xemodex. - the only way to go if the CEM is the problem. 2007 V70.

Whitewagon2 · Jul 6, 2023

hoonk said:
I would not count on your Ebay CEM working without jumping through many hoops.

1. As far as I know - the dealer can't program/flash a USED Cem to work in your car (using the only method they have, VIDA)

2. Someone like xemodex can fix or program a used Cem to work in your car. And they are in Canada.

xemodex can fix and return control units in less than 2 days sometimes. I think they work nights!

What's wrong with yours? Why do you want or think you need to replace it?

I think I’m probably going to go the xemodex route because they do seem to have a quick turnaround time!

I’ve been having issues of my car just completely dying while I’m driving. I’ve tried cleaning sensors and checked out a few other things. I’m going to remove the CEM and clean it since my research so far has shown that corrosion in the CEM connections could be causing it. If cleaning doesn’t show any results, I want to be ready to completely replace the CEM.

vtl · Jul 6, 2023

Define "completely dying"?

Whitewagon2 · Jul 6, 2023

vtl said:
Define "completely dying"?

Car just completely stalls, loses power. Then I put it in park, take the keys out, restart. It will start again, make a little rumble and completely dies again. Then I repeat (put in park, take keys out, start again), and it will do it maybe one more time then eventually starts up again and goes back to normal.
Then it’s usually good for the rest of the day.

vtl · Jul 6, 2023

Whitewagon2 said:
Car just completely stalls, loses power. Then I put it in park, take the keys out, restart. It will start again, make a little rumble and completely dies again. Then I repeat (put in park, take keys out, start again), and it will do it maybe one more time then eventually starts up again and goes back to normal.
Then it’s usually good for the rest of the day.

Why do you think it's not a fuel pump or PEM (it's controller)?

hoonk · Jul 7, 2023

Whitewagon2 said:
Car just completely stalls, loses power. Then I put it in park, take the keys out, restart. It will start again, make a little rumble and completely dies again. Then I repeat (put in park, take keys out, start again), and it will do it maybe one more time then eventually starts up again and goes back to normal.
Then it’s usually good for the rest of the day.

You might want to actually diagnose (or have someone actually diagnose) your problem BEFORE sending your good CEM off to be checked and not fix your problem. (or dicking around with an Ebay unit that will never work)

Your failure - is NOT a common CEM known problem.

But - discuss this with xemodex, they will want VIDA codes and any other symptoms you might have. At this point unfortunately you are guessing and grasping at straws - and that can get very expensive and frustrating.

What codes do you have in ALL the control units? Preferably using a scan tool such as VIDA or an equivalent?

Sorry for your troubles.

Whitewagon2 · Jul 7, 2023

hoonk said:
You might want to actually diagnose (or have someone actually diagnose) your problem BEFORE sending your good CEM off to be checked and not fix your problem. (or dicking around with an Ebay unit that will never work)

Your failure - is NOT a common CEM known problem.

But - discuss this with xemodex, they will want VIDA codes and any other symptoms you might have. At this point unfortunately you are guessing and grasping at straws - and that can get very expensive and frustrating.

What codes do you have in ALL the control units? Preferably using a scan tool such as VIDA or an equivalent?

Sorry for your troubles.

I am not certain, no. I’m only asking this question to get all my ducks in a row for IF this is the issue. I’ve tried doing a OBD2 reading, but unfortunately that function doesn’t work on my car (only gives an error message each time - this could also point to a bad CEM I’m thinking?). I’m planning to clean the CEM over the weekend and take a look to see if it’s corroded. And I have an appointment at a Volvo dealership for them to do a full diagnostics reading (but the earliest appointment I could get isn’t for another 2 weeks).

Looking around internet Volvo forums, groups & blogs I’ve found many posts about CEM issues causing stalling though. Again, im not saying for sure that’s my issue im just trying to cover all my bases.

vtl · Jul 7, 2023

Whitewagon2 said:
I am not certain, no. I’m only asking this question to get all my ducks in a row for IF this is the issue. I’ve tried doing a OBD2 reading, but unfortunately that function doesn’t work on my car (only gives an error message each time - this could also point to a bad CEM I’m thinking?). I’m planning to clean the CEM over the weekend and take a look to see if it’s corroded. And I have an appointment at a Volvo dealership for them to do a full diagnostics reading (but the earliest appointment I could get isn’t for another 2 weeks).

Looking around internet Volvo forums, groups & blogs I’ve found many posts about CEM issues causing stalling though. Again, im not saying for sure that’s my issue im just trying to cover all my bases.

CEM-L are rarely go bad, unless flooded.

CEM has a bunch of power controlling relays, which, as datasheet says, supposed to last 100500 million years, but they still die occasionally. A Volvo-aware electrician will be able to read the specific codes with DiCE/VIDA and figure out which one goes bad. In my CEM it was relay controlling the power for BCM (ABS), I simply desoldered it and replaced with a good used one.

daninater · Jul 7, 2023

Whitewagon2 said:
CEM question.
2005 XC70
If I order a rebuilt CEM off eBay, would it need to be taken to a local Volvo dealership to be flashed? Looking for the cheapest way possible, as I’d want to install the CEM myself. Just wondering if anyone has any experience with this.
Basically I’m wondering if I’d be able to replace CEM without having to send it off, or be without a car for an extended period of time (my job requires transportation)! Thanks!

I don't think it's your CEM at all. I'd attend a quick youtube university class and try the easy stuff. Unplug your mass airflow sensor and see if it starts and runs. Check if it has fuel pressure and don't spray gasoline in your eyes. If not maybe your fuel pump control module. Or fuel pump sending unit. Or fuel pressure sensor.

Whitewagon2 · Jul 7, 2023

daninater said:
I don't think it's your CEM at all. I'd attend a quick youtube university class and try the easy stuff. Unplug your mass airflow sensor and see if it starts and runs. Check if it has fuel pressure and don't spray gasoline in your eyes. If not maybe your fuel pump control module. Or fuel pump sending unit. Or fuel pressure sensor.

Thanks for the suggestions! Wondering if you have any insight as to why it seems to also be temperature related? Issue started last year (car would feel like it was about to stall, but never quite would) around September. Then when winter hit it disappeared completely. Didn’t return again until the end of May when it started getting hot out, and has been getting worse ever since.

That’s another reason I was looking into the CEM, because I read that it can overheat.

daninater · Jul 7, 2023

Whitewagon2 said:
Thanks for the suggestions! Wondering if you have any insight as to why it seems to also be temperature related? Issue started last year (car would feel like it was about to stall, but never quite would) around September. Then when winter hit it disappeared completely. Didn’t return again until the end of May when it started getting hot out, and has been getting worse ever since.

That’s another reason I was looking into the CEM, because I read that it can overheat.

Your CEM would overheat after driving it not when it's cold and you're first starting your engine. Not the CEM not the CEM. Stop thinking about the main computer, you will not resolve your issue if you fixate on the central electronics module. Air conditioner though? That could be it, add that to your list.

Oh also, go to autozone or someplace and take a picture of every code they can pull. Maybe your code reader isn't good, or there's a user error issue, no clue. They don't charge you and can at least can for regular codes. They can also test your battery and alternator. See if it works for them. If there aren't codes or are codes that will be good data to go on. Record a video of it starting or not starting and post a link.

Air Conditioning Compressor Failing
-Your only running the air conditioning when it's hot outside and when it's engaging with the failing compressor is bogging down your engine when you start it. Turn off the air conditioner and see if it effects your issue. If it's gone now you may have isolated it.

Fuel Pump Failing, Fuel Pressure Sensor, Fuel Pressure Control Module
Your failing fuel pump/control module/senor, which is on its way out, which is cooled by fuel or whatever, isn't performing in the summer heat, pumping less dense fuel to your engine. Or some other ignition component is behaving differently. Spark plugs? Ignition Coils? Fuel injectors? MAFm I don't know.

Your car has denser air, and denser fuel in the wintertime, more bang for its buck at ignition during cold start. You're running less accessories. worn components are working ok enough to go unnoticed.

hangya · Jul 7, 2023

I would, also add to the list the thottle body, even though its 2005 can be dirty, or hard to move, also vacum lines are all good? You may not have 1 thing which is wrong, but a combination of small things, check all what other users been posted, thats your best bet, to repair your car in budget, Don´t be a hero! We all been there, thats why everyone try to help.

Keep us updated!

GRUENDIG · Jul 7, 2023

Whitewagon2 said:
Car just completely stalls, loses power. Then I put it in park, take the keys out, restart. It will start again, make a little rumble and completely dies again. Then I repeat (put in park, take keys out, start again), and it will do it maybe one more time then eventually starts up again and goes back to normal.
Then it’s usually good for the rest of the day.

Check (Main relay, engine management system). Mine did the same, could not find it until one day it completely failed.
Don't know on your car but mine was FMA3 located in engine compartment. (2007 V70)

ZZZZZZZ · Jul 7, 2023

I agree with all the suggestions. Locally or even an hour or two away, look for someone with VIDA. Maybe someone on FB with Volvo clubs? You need to be able to get a good read and understand the health of the system or it's going to be frustrating and expensive. VIDA will review each module and check nominal values, etc., communication and then you'll find your problem. It's like using a great flashlight, looking in a pitch black forest...

Whitewagon2 · Jul 7, 2023

daninater said:
Your CEM would overheat after driving it not when it's cold and you're first starting your engine. Not the CEM not the CEM. Stop thinking about the main computer, you will not resolve your issue if you fixate on the central electronics module. Air conditioner though? That could be it, add that to your list.

Oh also, go to autozone or someplace and take a picture of every code they can pull. Maybe your code reader isn't good, or there's a user error issue, no clue. They don't charge you and can at least can for regular codes. They can also test your battery and alternator. See if it works for them. If there aren't codes or are codes that will be good data to go on. Record a video of it starting or not starting and post a link.

Air Conditioning Compressor Failing
-Your only running the air conditioning when it's hot outside and when it's engaging with the failing compressor is bogging down your engine when you start it. Turn off the air conditioner and see if it effects your issue. If it's gone now you may have isolated it.

Fuel Pump Failing, Fuel Pressure Sensor, Fuel Pressure Control Module
Your failing fuel pump/control module/senor, which is on its way out, which is cooled by fuel or whatever, isn't performing in the summer heat, pumping less dense fuel to your engine. Or some other ignition component is behaving differently. Spark plugs? Ignition Coils? Fuel injectors? MAFm I don't know.

Your car has denser air, and denser fuel in the wintertime, more bang for its buck at ignition during cold start. You're running less accessories. worn components are working ok enough to go unnoticed.

It’s not the air conditioner, I tested that theory already (it’s happened while both on and off).
The problem DOES only happen after driving it. Never at startup has it occurred (except right after a stall, might take 2 starts to get it going again). It happens roughly 15-20 minutes into the drive.

GRUENDIG · Jul 7, 2023

Whitewagon2 said:
I am not certain, no. I’m only asking this question to get all my ducks in a row for IF this is the issue. I’ve tried doing a OBD2 reading, but unfortunately that function doesn’t work on my car (only gives an error message each time - this could also point to a bad CEM I’m thinking?). I’m planning to clean the CEM over the weekend and take a look to see if it’s corroded. And I have an appointment at a Volvo dealership for them to do a full diagnostics reading (but the earliest appointment I could get isn’t for another 2 weeks).

Looking around internet Volvo forums, groups & blogs I’ve found many posts about CEM issues causing stalling though. Again, im not saying for sure that’s my issue im just trying to cover all my bases.

When my car died like yours, I could not connect with my scanner.
Only when the relay worked again could I read thru the OBD2.
When the relay finally died, the scanner would never connect. Replaced relay and it never happened again and scanner would read car.

Whitewagon2 · Jul 7, 2023

GRUENDIG said:
When my car died like yours, I could not connect with my scanner.
Only when the relay worked again could I read thru the OBD2.
When the relay finally died, the scanner would never connect. Replaced relay and it never happened again and scanner would read car.

this is helpful, thank you! So you had the same issue with your car dying randomly when driving, but then would start up again and drive fine immediately after?

CEM installing

Whitewagon2

vtl

hoonk

GRUENDIG

Whitewagon2

vtl

Whitewagon2

vtl

hoonk

Whitewagon2

vtl

daninater

Whitewagon2

daninater

hangya

GRUENDIG

ZZZZZZZ

Whitewagon2

GRUENDIG

Whitewagon2

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