2007 Volvo s40 Intermittent module failure

Jason Owner/Technician San Luis Obispo, California Posted   Latest  
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Network Communications
2007 Volvo S40 2.4i 2.4L (B5244S) 5-spd
Intermittent Module Communication Failure

This is my first post. I have been fighting with a Volvo that intermittently will not start, not allow the ignition key to be removed, and intermittently turns on the brake warning light, anti-skid light, and engine system service urgent message on. The one time I have been able to catch this condition with a scan tool connected, it would not communicate with the tool. I am looking for a direction. I have graphed the communication between the CEM and the ECM. I t has a grundle of codes when the failure occurs. One that seems to reoccur is a problem with the power steering module and a configuration problem has been found. I have removed the power steering module from the system and the code does not appear while disconnected, Some part of the communication looks different, but am unsure if this is normal. Does any one have some saved wave forms or suggestions? Thanks in advance for your attention, I know time is precious for all of us.

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Bob Instructor
Phoenix, Arizona
Bob Default
 

Have you checked your power/ ground connections? And the brake switch(es)? I have seen bad grounds raise hell with communications and throw multiple codes. Hope this helps.

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Caleb Technician
Mishawaka, Indiana
Caleb Default
 

Have you been able to get a saved capture of the network when it is broke?? There are plenty of YouTube Pico and other videos showing known good CAN waveforms. Maybe if you could post a shot of the broken network we can help you.

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Matt Technical Support Specialist
Dallas, Texas
Matt Default
 

It appears high speed CAN on DLC pin 6 &14 and low speed CAN on pins 3 & 11. They directly wire to the central electronic module (CEM). The CEM appears to be teh gateway on this vehicle. Do you have comm w/ the CEM during the event? If not continue testing as you would any other CAN network.

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Michael Technical Support Specialist
Commack, New York
Michael Default
 

CEM controls majority of the vehicle's functions including interior and exterior lighting, front and rear wipers and washers, sunroof, seat belts, seat heaters, alarm system, accelerator pedal, fuel pump, fuel level sensor, even the blower fan. CEM is also responsible for supplying power to majority of other modules in the car like SRS, ECM, TCM, IAM, ICM, AUD, etc. CEM is also a central gateway…

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Jason Owner/Technician
San Luis Obispo, California
Jason Update
 

Thanks for your responses. I have checked powers and grounds they look good. I have caught the failure while plugged in with a scan tool and there was no communication with the scan tool. I have checked the connectors on the CEM and there is no evidence of water intrusion and the connection points look good.

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Caleb Technician
Mishawaka, Indiana
Caleb Default
 

Thanks for the response James. Do you have a scope? Can you connect it an get a waveform when the car is broken you can post for us too see?? When you say no comm with the scan tool, is that all modules are no comm or just certain modules??

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Jason Owner/Technician
San Luis Obispo, California
Jason Default
 

I do have a pico, but have been unable to capture a pattern during the failure. When the scan tool was connected it would to communicate with the CEM. Which is the only module the scan tool talks to.

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Chris Diagnostician
Commack, New York
Chris Default
 

To me, that seems like your answer right there. The only thing the you can talk to is the CEM. The rest of the vehicle is cut off. The CEM is the Gateway to all the Networks. Right now it seems that the gate is closed. You can attempt a battery reset to get the CEM to stop acting a fool. What are the chances that you have multiple different CAN lines down at the same time? You have to look at…

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Samuel Technician
Somers Point, New Jersey
Samuel Default
 

This is the best direction....I myself get trapped in the worm hole. If all is well up to the CEM and nothing happens after, then we can agree that is the issue!

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