2004 XC70 Wierd electrical issue + code ECM003

[precopster]

The generic clone for $117 should be fine; just check seller's feeedback. Absolutely no need to purchase a genuine tool as the clones read codes very well. The only real use for genuine readers is when you want to upgrade software as the clones aren't licensed for this task.

I've now reprogrammed 7 or 8 throttle modules with my clone Dice reader and no problems with that (though I'm not using Vida's software for this.

The only difference between the real Vida and the Chinese one is licensing which the Volvo servers can recognize as illegitimate.

The Vida software contains the location of just about every nut, bolt and module on the car.

Reading the car with Vida is essential to your next step. Once you have the code(s) post them up here and we'll try and help you out.

[jimmy57]

When you read the full car you are going to see a lengthy list of codes. The CEM will be reporting a lot of codes. The CEM could be the problem but another module or CAN comm wires shorted can cause this.

[bugeye]

The CEM is located above the drivers left foot. It is rectangular about 5" wide, 10" long with a bunch of small square boxes, relays and a bundle of wires/connector. I had to lay on my back with my head at the brake looking up. On the outboard (fender) side is a clip to flex to allow the CEM to be released and lowered to the floor elevation. I numbered each relay, then took a picture to document the relay location on the board. The electrical connector is secured with one bolt. The connector is tight. Slight wiggling was required to release from the board. I sent mine to XeMODeX. Plug and play, no more issues.

[mikeamondo]

So... the problem has continued. Car died again today and needed towed as it would not restart after a half hour or so. Each time, the problem has disappeared, and all lights gone away. As recommended, a generic code reader is on the way... one of the clones out of hong kong, and it should be here in a day or so. Quick question.... if the cem is suspected, would it make sense to pull it and clean the contacts before replacing it to see if that helps? What should he use to clean the contacts with once it's pulled from the car?

Thanks!

[oragex]

How many days did he drive the car since the purchase, without having the issue? I wonder if the issue was there before, or it only started after the rain. Rain pouring by the sunroof, it'd point to water on the electronics that are underneath front seats, but given it was only a light rain, I doubt it had time to get there. More chances the issue was known by previous owner (and thus the reason of selling it), I've seen a few owners on forums with similar electronic issues that are not obvious to fix. Usually is related with the CEM but also with other components in the communication circuit, that can affect communication with CEM and cause various symptoms. The CEM itself has to be sent to a electronics repair shop (I think http://www.xemodex.com/ is one of them).

[mikeamondo]

He had it a couple weeks.... previous owner seemed to have significant Volvo knowledge and family ties to a dealership of some kind.... possibly even a previous Volvo dealership... not certain. He seems like a decent fellow; I hate to blame him. Regardless, it was a private sale, so buyer beware, as they say. Is there a leaking issue with the plenum under the wipers that can allow water to drip down to the cem? There's not enough evidence to say for sure, but there MAY be a correlation to wet weather and the problem reoccurring.

[jimmy57]

Water on CEM is the 2005 and later fault. The way wires go inside car to CEM is different on 2005 on vs 99-2004.

[mikeamondo]

Hello! Here's an update and another question.... Car has been sitting since the day it needed towed. Our scanner arrived, but my son had trouble getting it to work.... everything he had was Windows 8, which was wrong for the scanner. The lights & message on the dash changed.... Transmission Service Required came on and stayed.
After the scanner failure, we decided to have it read at a local shop, which claims to have a factory spec scanner. They are going to read it Monday. I'd like to get a bit more info before they call.... I'm 800 miles away and don't want to be taken advantage of. I'm afraid they will just say it needs a transmission.
With "Transmission Service Req" displaying, what would you think we should expect from a good scan? Could the failing CEM or other module as discussed already also cause that message?
He drove the car about 10 miles to the shop, and the light stayed on, but it ran at speeds around 40 mph with no problem. He did hear a 'rumbly' noise, but he thought it might be a wheel bearing. Do tranny's ever make that sound when things are going awry? Any suggestions or advice prior to the call coming from the shop would be appreciated.... things to watch for.... don't let them tell you ______.... etc.

Thanks!

[bugeye]

My opinion. If during the last drive the transmission shifted as a normal transmission would shift, then focus on the message errors. The CEM is a circuit board filled with integrated circuit chips and external relays. could be effected by temperature and moisture. My CEM went to XeMODex from our son's car 250 miles away, 2004 XC70. We had the car scanned by Volvo. Many error messages on multiple computer modules. Volvo cleared errors and advised to watch for which one reoccured first. They all happened at once pointing to the CEM. The connector to the CEM is about 1.5" x 3" with 30+ wires (from memory). Our connector was clean, no corrosion. For the transmission, multiple drain and fills with driving in between. Check the color and smell of the trans fluid on the yellow dipstick. Use Mobil 3309 fluid from Amason, about $65 for a case of 12. I did 3 drain/fills so as not to shock the trans with fluid property change. Takes about 3.5 quarts per drain/fill. Please advise your findings.

[mikeamondo]

Thanks for the reply, Bugeye! I'm hoping the CEM is the culprit. The shop scanned the car today and found..... nothing. He said there were no codes stored and the transmission service required light was on due to the fact that at 103k miles and change it was coming up on the transmission service interval at 105k. We speculated a few minutes on possible causes..... he said he thought moisture on the center console leaking through the CEM below could have caused our symptoms, and now... a month down the road or more, it had dried out. He said the car started and ran as normal every time while they've had it. My son will be picking it up in the next day or so, and assuming it starts fine at that point, his advice is to drive it and see what happens.

Looking back over the symptoms.... weird and changing messages following issues of non starting... and then the disappearing of those messages and trouble free driving.... followed by a repeat of the failing to start and more messages..... it seems like the CEM having gotten wet when the sunroof was left open in the rain makes some sense... do you agree?
Do you agree with the mechanic's assessment of the transmission message?
How hard is it to get to the CEM to look for moisture, and are the directions/videos online to help?

Thanks for all the help to everyone on this! Hard to diagnose an issue with your kid's car from 800 miles away!

--Mike