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Help with Vida Diag codes - Brake Failure Warning - Comm issues

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mikeamondo
Posts: 104
Joined: Wed Mar 26, 2014 8:03 am
Year and Model: 04 XC70 - son's car
Location: West Virginia, USA

Help with Vida Diag codes - Brake Failure Warning - Comm issues

Post by mikeamondo » Sat Aug 12, 2017 8:37 am

Car - 2004 XC70
Diagnostic Equipment - Vida / Dice although I'm very inexperienced with it.

I've been trying to track down an intermittent communication / module failure issue for a month or so now. I can go 200+ miles between issues. Here is a link to the thread I was working thru ... viewtopic.php?t=81959 if you'd like the full, in depth history.

Right now, I've done the following:
Pulled the ECM and TCM and cleaned the pins with contact cleaner & toothbrush, replaced with a nice coating of dielectric grease.
Pulled the CEM, removed the connector and did the same cleaning / greasing on the pins, and reinstalled.
Took out the air cleaner box, and removed a few of the connectors located on that plastic riser - I could only get 3 of them to come apart.... gave up on the rest. Those I got apart, I cleaned as above and added grease.

RESULTS - so far, I can say it feels BETTER.... but I still had the issue last evening. No consistent timing / conditions on it occurring. I think it's better because the issue seems more infrequent and having fewer faults than when I started.

The Event - Driving home, 12 miles into the drive, ac goes warm, tach, speedo and temp guage die, Brake Failure Warning - stop safely' warning on dash, ABS & brake light on. No actual braking issues, of course, and no transmission warnings or limp mode. Continued home, and the fault remained as described, car running great. Turned engine off and restarted and the problem was gone. Historically, I can say I may drive another 200 miles or more before it happens again.

Pulled the codes with Vida.... after that single restart.... Here's what I got from around the time of the event:
BCM E000 Control Module Comm - Faulty Communication. 1 cycle ago
372 CEM E000 Control Module Comm - Faulty Communication 2 cycles ago
372 CEM 1A5F - Communication with BCM 2 cycles ago
CEM 1A61 - Comm with TCM Missing 2 cycles ago
CEM 1A62 - Comm with ECM Missing 2 cycles ago
284 ECM 9400 - Brake pedal Sensor Signal Missing -- 1 cycle ago

I'm starting to think CEM or one of the relays on it.... What do you guys think? I really want to avoid blindly spending hundreds of dollars taking a stab in the dark here.....
Thanks!

Fataqui
Posts: 12
Joined: Wed Apr 19, 2017 1:41 am
Year and Model: 2007, XC70
Location: Maine
United States of America

Re: Help with Vida Diag codes - Brake Failure Warning - Comm issues

Post by Fataqui » Sat Aug 12, 2017 10:19 am

Hi

After reading everything you posted I would definitely be looking at getting the CEM repaired or replaced. Up where I live you can get a good used one from a junk yard for $50 or $60. I would personally do that and then send your unit and the good used unit up to xemodex and have them transfer your units info to the good used unit. That would run around $300 to $350 depending on how much the junk yard would charge you for their unit, or you could just get a complete replacement unit from xemodex which will have all the upgraded relays in it, and those cheap relays Delphi used are mostly the main reason Volvo CEM(s) fail. Now, for me doing one or the other would entirely depend on how long I would be keeping the car that has the problem. As a side note... I have seen many customers of mine do both those things with great success so either way will work, but for longevity sake the complete replacement is what I would do if it was my baby, LOL! And yeah, I am laughing, but when a car has taken you around the world many times over, 700,000+ miles and / or holds many irreplaceable memories you take care of it, no questions asked!

precopster
Posts: 6500
Joined: Sat Aug 21, 2010 12:20 am
Year and Model: Lots
Location: Melbourne Australia
Australia

Re: Help with Vida Diag codes - Brake Failure Warning - Comm issues

Post by precopster » Sat Aug 12, 2017 2:39 pm

As a born pessimist I understand where you're coming from so let me share what may work.

These 2004 CEMs are not Delphi units like the later ones and therefore swapping relays won't work. Your symptoms seem pretty consistent with CEM failure.


If you get hold of a used unit contact Yagger or Doublebug. They will send you some photos of which pins to short. on the main IC (pins 8 & 9 from memory) so they can extract the programming and rewrite the new (used) CEM over the internet. You'll need a pair of tin snips to tear each corner of the aluminium heatsink cover over the main IC. Henry (doublebug) and I have successfully rewritten about 6 CEMs on various cars. Total cost is one hour of their time which is a lot less than XeModex' fee when you aren't 100% certain of the diagnosis.
Current cars:2002 XC70, 2001 V70 T5, 2006 XC90 2.5T, VW Transporter 2.5TDI

www.precisioncarmodules.com.

mikeamondo
Posts: 104
Joined: Wed Mar 26, 2014 8:03 am
Year and Model: 04 XC70 - son's car
Location: West Virginia, USA

Re: Help with Vida Diag codes - Brake Failure Warning - Comm issues

Post by mikeamondo » Sat Aug 12, 2017 6:47 pm

Thanks for the input... @Fataqui --- Is there any way to be sure you're getting a good used CEM? I mean, if you started my car, even drove it for a couple days, you'd say the CEM must be just fine. Heck you could drive it for a week. And ... how much is that spiffy all new upgraded one from those guys?

@precopster --- lots of stuff in there that was gibberish to me, but I think I got the basic idea. So, would you be shorting pins and tearing heatsink covers on the used one I picked up from a junkyard... I assume? So the same basic idea, just those guys can program it remotely? May be a bit beyond my technical ability.

Does CEM failure often present symptoms this intermittently?

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