2004 XC70 Wierd electrical issue + code ECM003

[mikeamondo]

UPDATE! So this didn't take long.... after driving the car for all of a day, the problem has reoccurred. As you may recall... the car performed flawlessly for the mechanic and a scan showed absolutely no codes. And then.....

He tried to start the car. It turns over fine, and will fire and start, then immediately die. Apparently, this is pretty much how it happened on previous occasions... a fire, momentary run of a second or so and then it dies. This time, unlike previous occasions, there were zero messages or warning lights on the dash. Then... after a couple hours, the car started, now with the check engine light on.

Some have suspected the CEM due to leaving the sunroof open in a rain storm... I understand it is below the center console. If that makes sense, can someone provide some instruction on how to get in and see if there's any visible moisture?

Any other starting points? What do you make of the fact that it didn't show any codes with the scan at the shop? The tow truck driver suggested fuel pump... apparently he'd seen that before on Volvos. What other modules might cause the things we've seen? Failure to start with odd combinations of warnings/lights or none at all.... and now the CEL. Another scan might be possible, if the cel stays on, but at $50 a pop, that will get expensive if it continues to show nothing!

[precopster]

Search Matthews site for "VM Ware image"

You can successfully run an image of XP rumning Vida on any operating system including Win 8 and it will still talk to that Dice scanner.

Beats the stealer because you can read it when it fails; usually the codes are gone by the time you have it read at the dealer, making it very frustrating.

[mikeamondo]

So it's NOT uncommon for codes to go away? That's the first I've heard of that! I thought once they were generated they were stored until read.... If the CEL light is on, should there definitely be a code in there as long as it's still lit?

[jimmy57]

The CEM is under the left side of dash. It is immediately behind where the OBD-II plug is located. The SRS (airbag) module is under the center console and it is a low speed network module and your problems as listed are not low speed network issues. The panel with LEDs around gear lever is a module too but it is connected to TCM and that is done with a direct connection to TCM that is not the CAN network.

ECM 003 is a code that sets when the ECM misses information over the newtwork. The ECM needs to be removed and the terminals in plug plate below need to be checked with a correct male terminal for drag indicating they are going to make good connections. The ECM pins need to be looked at closely to assure they have no corrosion. The TCM connections need to be checked the same way. P2 models are beginning to have more troubles with ECM and TCM connections. IF there are any CEM DFxx (xx can be 11, 12, 13, 14, 15 , 16 for high speed network issues) codes as these indicate faults with wiring on high speed network shorted to ground, power, each other. Pin connection issues at modules are not stored by CEM as DF series codes. It would be a good idea if the CEM connectors are inspected also.

The fault could certainly be CEM failure only. A 12V DC computer cooler fan cable tied to front of CEM over the vents might be an option. Power supply could come from the fuse for driver's door module in the fuse panel on the left end of the dash. The fan will run after key is off as the windows are part of the extended power down features. That is actually a good thing though.
I think Radio Shack has those fans. I get them at an electronics chain store here but I don't know what choices you have where you are.

[mikeamondo]

Wow.... Ok, so a couple questions
1) Where do I get the correct male plug, and is the check to make sure it has some "grip" to it as you pull the plug off the pin? And how do you fix it if it doesn't?
2) Are there good instructions for the locating and removal of the ECM, TCM and CEM? Are they accessible or truly a pain in the ass?
3) I'm assuming it's common for the CEM to fail due to overheating? Are the "vents" you mention on the CEM obvious once we get in to it? The CEM is the one others have mentioned having rebuilt by Xeomdex, correct?

Thanks!

[jimmy57]

I get the terminals at the dealer. Parts may have to ask their tech which one to use.

The ECM and TCM have a tool to use to release the modules. There are probably some posts about how to use screwdrivers to do the same.
Cem is removed on 99-04 by removing the OBD-II plug and then on the left side of CEM bracket is a white painted metal bar that is pushed to the left. Then you pull bottom of CEM to the rear a few inches and the CEM will come down out of bracket.

The vents will be obvious on the face of CEM.
CEM is the one mentioned by XEMODEX. It is the master module on the two networks and acts as gateway between them for data that needs to be transferred between the networks.

[precopster]

I got rid of a customer's ECM-003 by simply removing the ECM and cleaning the edge connector with contact cleaner. The car was an '03 XC70 with multiple throttle codes. It had already received new Bosch MAF and throttle.

A $30 removal tool and a can of contact cleaner spray and an old toothbrush can save you a lot of bother.

[jimmy57]

I agree. A first effort before you go to any trouble would be to get the ECM and TCM out and use WD-40 or other cleaner/oily spray and insert and remove and insert and remove few times and see if the problem goes away, at least for a while.
http://www.ebay.com/itm/like/380809599504?lpid=82
this ebay auction shows the tool. The two ends with the U notches go around a nub that sticks out of the violet colored plastic lock slides. If you get two really slender 15 inch +/- long screwdrivers and slide those two lock slides at the same time towards front of car, the ECM will come up and be released. The TCM is exactly the same. Install is reverse of removal as the slides have to go to rear simultaneously to get it installed. Key off when you do this 3 minutes after key off to be sure all is offline and powered down.

[precopster]

So it's NOT uncommon for codes to go away? That's the first I've heard of that! I thought once they were generated they were stored until read.... If the CEL light is on, should there definitely be a code in there as long as it's still lit?

The codes will become stored after 3 successful cycles, even if CEL is on during one of those cycles. I want to have codes current on any car WHILE I read them so I can try various tests and repairs to eliminate the problem.

[mikeamondo]

Great responses, everyone! This is all starting to make some sense. I have ordered a ECM removal tool from ARD Tuning. We will be visiting my son July 4th weekend and have set aside time to work on cleaning up the contacts on all three modules. The Youtube videos about that tool show it making the removal a 10 second job.

For the cleaner.... I've never used wd40 for that kind of cleaning. Is an 'oily' cleaner better for this purpose? The cleaners I've always used for computer part cleaning are not oily at all and evaporate completely dry. How about using dielectric grease after the cleaning, when you reinstall, like you might use to protect battery cable connections?

When you wire the electric fan from radio shack into the fuse box.... does that require soldering or are you jamming the wire in behind the fuse when you insert it.... or is that a place you can splice the wire to the power lead? And... is that just a cpu cooling and / or a computer case cooling fan?

Sorry if these questions are driving you all crazy, but keep in mind.... I personally have never even seen this car.... and won't until it's time to start messing with it. Long distance car repair.... ugh.

Thanks to all!