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Discussion Starter · #1 ·
Hi to all, V50 2005 T5 AWD 242000km

My car misbehaved recently, but intermittently - so hard to diagnose.

It all began with a BRAKE FAILURE - STOP URGENT. Its stopped the engine, restarted and it went away.

A couple of miles later, it came back. Then Cruise Control quit, then all gauges went dead, along REDUCED ENGINE PERFORMANCE.

I pulled info safe place then again, stopped the engine.

Restarted, all was fine. Once home, ran a Vida and got all sort of funky errors, not related to each other but by memory:

  • ECM communication
  • Pedal sensor
  • Knock sensor too high
  • CEM missing signal

Cleared all errors, updated the scan and all was fine.

Alternator gave 14.2V on idle, battery was between 11.8 and 12.2V at rest.

- - -

Tonight, as I embarqued a 250km ride, all of it came back but.... intermittently! I mean the BRAKE FAILURE showed/hide sometimes seconds apart. REDUCED PERFORMANCE kept showing, and engine showed poor performances.

Other than that, car ran fine on my 60km way back home. I cancelled the long trip.

Odd fact: everytime the codes appeared, I ran an ODB scanned roadside, and the errors went away. Only to reappear once driving. Then went away, then back. Still now power from car though.

- - -

Back home, ran a Vida and still got those same funky errors, and again cluster messaged showed and hide on/off.

See pics below. Those are errors I got after clearing codes and scan again.

So..........

Bad battery?
CEM acting up? All those errors cant be related.
Any clue?

Thanks to all!

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Font Parallel Rectangle Screenshot Electric blue

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2007 S40 2.4i / 2007 C70 T5
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That seems like a CEM loose connector. Have you ever had an immobilizer error in the dashboard which didn't let you fire up the engine?
 

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Hi Facusan, nope: no immobilizer error. Easy to remove the CEM?
 

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Look at this post that I replied to as to how to remove the CEM.
I would inspect the CEM connectors for being loose. Unlock, remove and reset all of the CEM connectors.
Inspect the CEM connectors and CEM pins for any water damage and green growth corrosion.
From the 1st pic posted, looks like you got a bug in the computer.
(50) 2010 Volvo s40 electrical | SwedeSpeed - Volvo Performance Forum
 

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Discussion Starter · #7 · (Edited)
Restarted the car this morning without an hesitation, within seconds : Brake Failure message. Could it be the culprit? No leak and level is fine.

Cant get the CEM out, its retained by wires/connectors. Its completely dry though. But ive noticed this: two exposed wires. They dont seem to contact each other. But what are they for? What's controlled by them?

Lastly, as it seems the plastic connector is damaged, can I replaced it with a JY one?


Thanks!

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Discussion Starter · #8 ·
OK CEM is out. Completely dry and sound: no sign of shorts or the likes. All is clean. But that connector (see pic on top).

What is that black/gray wire for?

If not CEM what could cause all those unrelated errors?

Thanks!
 

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Now this!!!! I replaced the CEM and now I get a BRAKE FAILURE and IMMOBILIZER.
Yeah, that's probably a serialization mismatch. I think the CEM has to be flashed for the modules in the system.

The harness looks like the culprit to me. It's totally trashed. You need to splice a new one in, unless it's on the CEM. But then you probably have to tow it in and have them reflash. And are you sure it is the right CEM? Needs to be exact same part number. If you splice the donor harness in, I recommend conformal coat, waterproof heat shrink,then encapsulate with silicone caulk. Each conductor.
 

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Discussion Starter · #11 ·
I might add that the CEM is in the car since I have it - 2 years so I must be the right one.

I will go to a junkyard pick up a connector and splice the wires.

how to get rid of the immobilized message?

could it be the battery? It make some smoke when I connected the - pole.
 

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I would deal with those wires with the insulation damage and the connector with the broken cavities before doing anything else.

Those 2 CEM codes (DF11, DF17) I remember from CAN network class, they taught us to go after DF codes first - as in "Do First" - because the network has to be communicating properly. Once you have a properly operating network, you can deal with whatever faults remain.
 

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I might add that the CEM is in the car since I have it - 2 years so I must be the right one.

I will go to a junkyard pick up a connector and splice the wires.

how to get rid of the immobilized message?

could it be the battery? It make some smoke when I connected the - pole.
Ah. You reinstalled the CEM, not replaced. Once you have good wiring, you may need to clear codes and drive a while to see if they come back. A spark and puff of smoke is typical. Make sure you connect ground first, so connecting hot doesn't result in an unexpected current path.
 

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A small arc is common when connecting the battery.

A large arc (and possibly smoke) often means there is a current draw. I would suspect the damaged harness is shorted if this is the case.
 

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Discussion Starter · #16 ·
Ok, will do. Now i cant run Vida as the car rfuses to ignite because of the immobilizer code. How to get rid of that?

and again, can i use a CEM connector for a JY car? Any year / option will do?

What function does the damaged connector / wire conrrils?

thanks
 

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Judging by the electrical tape repair on those plug wires to the CEM the culprit is very possibly right there in front of you.
Depending on what car you take the plug from it will have different pins populated, they are not all going to have the same leads as your car.
 

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Make sure all there are no loose connectors at the CEM, and those wires for sure need to be repaired.

That connector is labeled as "Roof 2". It's hard to tell by looking at the picture to which pins those wires are connected to. Try looking at the CEM, each connector has the pin number written on it. I checked in VIDA, and there are a few wires that are CAN related, that could explain the Immobilizer error.

Here's the CEM pinout:

https://www.swedespeed.com/attachments/cem-pinout-pdf.153881/

In this situation I would see if there is a way to salvage that connector and fix those wires. Worst case scenario, grab a connector from the junkyard and replace it. Try to remove the pins and install them in the new connector instead of just splicing all wires. The less splices, the better. You might want to grab a few extra connectors to practice with them first.
 

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A pic of the CEM and connector locations on the CEM. All of the CEM H-connector wires that I could find. Your car does not have all of the ones listed. 4/56 is the CEM. Follow around the dotted line for H:1 ect wires. This will show the H-pin location and wire color. Search list of components 8/48 ect to see where the wire goes.
 

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Discussion Starter · #20 ·
Hi to all, with the precious help of a fellow Swedester, we narrowwed down the culprit to be either a defective battery or the damaged wire on the CEM connector,

I will attempt to repair the wire connector, i have a spare one.

Space is very limited to work on the CEM, so usually people are getting it out. But... i cant take the harness with the damaged wire/connector out!!! So i have to work under the glove box.

Can the glove box be removed to gain a better access?

Any tip to help me take the wires out the damaged connector (see pic on top) and fit them into the new connector?


Thanks!
 
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