2004 XC70 Wierd electrical issue + code ECM003

mikeamondo · Post by **mikeamondo** » 06 May 2014, 11:31

Pretty much a Volvo newbie here... helping my son work thru an issue with his 04 XC70, automatic, which he bought a few weeks back. 102k miles. I'm about 800 miles from him, so this is 'thru the grapevine' as it were... but here's how I think it went down...

The sunroof was left open in a light rain and the interior got wet... not severely... but it puddled in the cup holders and took a couple paper towels to get it cleaned up

At some point after that, it started and then died in a parking lot and refused to restart. The check engine light and the transmission service required warning lights came on. Perhaps also, the limp home mode warning was on momentarily. Eventually, the car restarted and he was able to drive home where upon shutting off the car, it restarted with some difficulty. At some point in there, the service message appeared in the message window of the dash.... scroll down to read messages. The check engine light remained lit, but the limp home warning was gone.

At no point did he experience shifting issues with the tranny. He said the engine ran fine and the transmission shifted perfectly.

By the next day, the starting issue was gone, and it was starting and running as it had before... excellently. Also, the check engine light was gone, as was the message in the scroll down message center on the dash. All evidence of the issue was gone, and he has had zero repeats of the issue since the first occurrence 3 days ago.

He has an obd2 code reader and it pulled code U0073, which according to a thread over at Swedespeed, translates to Volvo code ECM003.
U0073 -- ECM-E003 -- Configuration error -- Faulty signal

Is this likely a result of the rain getting into the car? Another thread elsewhere suggested that was possible.
Should he forget about the issue until it reappears, or would you suggest getting it to a real Volvo Code reader?
Are the conversion charts I found elsewhere, OBD2 to Volvo codes accurate, and is any more info to be gained by having it read at the dealership / Independent shop?

Any help or guidance on this would be greatly appreciated! Thanks!

Andy... if I've missed anything... sign up an account and add to the post...

Post by **precopster** » 06 May 2014, 15:33

I haven't seen a non Volvo code reader that pulls "U" codes. Usually they begin with P . Are you certain your code reader reads in U format?

I doubt the sunroof issue is related to the engine code you specify.

More than likely it will affect another module such as SRS or seat.

Post by **jimmy57** » 06 May 2014, 17:29

Those code readers will read any codes that are classed as emissions related. The codes not read by that tool are where the facts will lie.

mikeamondo · Post by **mikeamondo** » 07 May 2014, 14:57

So... is the info posted above bogus or unreliable, then? Please have a look at this thread and let me know if you think it's accurate

http://forums.swedespeed.com/showthread ... stion-List

thanks!
Mike

mikeamondo · Post by **mikeamondo** » 07 May 2014, 18:36

So I think I've answered my own question here....

Background
OBD II is a diagnostic system tied to legislative requirements. A standardized fault tracing instrument can be connected to the data link connector (OBD II outlet) in order to read out diagnostic trouble codes and parameters. OBD II only contains the diagnostic trouble codes and parameters linked to emissions and thus cannot provide the same wealth of information as Volvo Diagnostics.
Volvo has its own diagnostic trouble code designations that follow Volvo's Onboard Diagnostics protocol (called DII from model year 1999).

Which means... the odb2 reader is showing codes that do, in fact, correlate to Volvo codes, BUT, those will only be Volvo codes relating to emission controls..... and in our case, with our electrical issue, there is likely something else afoot. Something.... more sinister.... than just an emission issue.... correct? Something that only a VIDA reader will show.... ?

Post by **jimmy57** » 07 May 2014, 20:55

Yes, OBD-II readers is like reading blood pressure, heart rate, and blood sugar. All really good to know but if you have broken cartilage in your knee those do nothing to fix a knee.

Post by **regent** » 08 May 2014, 08:39

You may be having issues from the water ingress below the cup holders into the electrical connectors underneath. This may create some config. fault messages. It is best to inspect that area with the battery disconnected, and do a nice clean up.

mikeamondo · Post by **mikeamondo** » 10 May 2014, 17:08

So... the issue has reoccurred. The car has driven for several days with out any lights, warning messages, etc, and no driving / operational issues. A trip was made to the store about 5 miles away and returned with no problems and parked. An hour or so later, the car started ok, but the only gauge on the dash that was working was the gas gauge, and the abs and brake light were on. Also.. the brake failure, stop safely warning message was displayed. The brakes, however worked fine. Drove about a mile and parked and shut off the car. Upon immediate restart, all the lights and messages were once again gone and the gauges were working fine.

So... hoping to get some suggestions here... obviously seems electrical / computer related. I saw several posts about overheating CEM's on the 04's in particular. Also, the electrical contacts on the ecm have been mentioned.

What is the CEM and what is the ECM? Where are they, and are they hard to replace? Is there a way to cool the CEM without switching to a heat sink equipped one? $500 is a bit stiff, right now....
We are going to pick up a VIDA scanner.... will that help diagnose?
Thanks!
Mike

Post by **marshallh** » 11 May 2014, 01:15

ECM - engine control module. It runs the engine is directly connected to the transmission module over a separate high-speed CAN bus. It also connects to the CEM over a low speed CAN bus.

CEM - Central electronics module. It is basically the main bridge between the engine and the entire rest of the car. It oversees everything else in the car, such as the climate control, ABS, SRS, radio, Dash controls (DIM), etc.

The CEM is constantly talking to the ABS and SRS controllers while you drive, making sure everything is fine. If suddenly it can't communicate anymore, it throws an error. The gauges and such are part of the DIM. If the DIM can't talk to the CEM, the gauges will freeze and you won't see anything.

Have you pulled the CEM and tried some electrical contact cleaned on the connection? That has solved similar issues for other people.

The SRS and ABS codes, if they persist, can be cleared with a DiCE and VIDA software, or by the dealer.
Also, with the scanner you can run a systems check while the problem is occuring and see what modules were affected by it. Then you can deduce where the problem happened.

mikeamondo · Post by **mikeamondo** » 11 May 2014, 04:57

Marshallh... wow.. thanks for the great post. The really clears up a lot. The mud is beginning to clear. Where is the CEM located and is it hard to remove for a relative newbie? And what scan tool would be a good addition to someone hoping to do some diy work at home?
There are several scanners on ebay from Hong Kong.... all in the $120 price range such as this one:

http://www.ebay.com/itm/Volvo-Vida-Dice ... ls&vxp=mtr

Titled as Volvo Vida Dice 2013A or similar. But then I saw a genuine Volvo scan tool in the Volvo box for $1799! Are the cheaper ones a decent option or cheap junk... or both? We already have a generic Scantron OBD2 scanner to pull emissions codes.

Thanks!