2004 XC70 Wierd electrical issue + code ECM003

[jimmy57]

Getting the tool is a good decision. Using screwdrivers is a test of one's patience.

The choice of a contact cleaner is not very important for this purpose. Dielectric grease is fine and is a good idea.

I am not a fan of Scotch-Loks but they do work well with low amp connections inside the car out of the weather. That fuse box is easy to remove from end of dash so that you can get to the backside of the fuse to find a wire to splice to.

No special tool needed for the CEM connector. It uses a bolt to hold the connector in. When you unscrew the bolt it pushes the connector off. Tighten the bolt until it clicks when you go back together.

[mikeamondo]

jimmy57 - thanks for the info... just about all is cleared up and we have a plan of action. On the back of fuse box, will it be obvious which wire comes from which fuse? I'm guessing it should be.

And... precopster:

The codes will become stored after 3 successful cycles, even if CEL is on during one of those cycles.

Where are they stored? If they were stored, shouldn't the shop we took it to have seen them? They said they had a "factory" level scanner, and they could find no codes in the system. Are "stored" codes non-retrievable? I think I'm still fuzzy on the terminology here...

Thanks!

[jimmy57]

The wires from the fuses are easy to visually trace on the rear of that fuse box.

If the shop uses Vida then they would have seen everything. If they have Autologic or Autel they still should have seen them.

If the battery went dead or was disconnected while the car sat then the codes are gone for that reason.

[leoxdeng]

Dear all

I'm fairly new to this forum (and to mechanics) - so please do bear with me for the below lengthy description of the problem with my car - I found this thread by googling 'brake failure warning message'.

For my very old 2004 XC90 T6 - I've recently replaced serpentine belt and tensioner/pulley - and for this job I removed ECM TCM modules as otherwise the tight clearance made the job literally impossible. I used a ECM/TCM removal tool and disconnected battery negative on a cold engine before the job. After the job, I reconnected battery and turned ignition to position II - did a test drive and all seemed OK.

Today I had the 3rd trip after the job mentioned above - and I was stuck in really bad traffic for 45 min - I pretty much didn't use the gas pedal as could just rely on pressing/releasing the brake to move at that slow speed. Then - suddenly - ignition was playing a bit funny - it had a 'clicking' sound multiple times (sorry don't know the technical language for this) - at first I thought it was due to engine being idle for too long - but then the frequency increased to once every 30 seconds also - at which time 'airbag service urgent' warning message also showed up.

I continued to drive (in bad traffic) - and suddenly the 'brake failure stop safely' message came up, as well as check engine light - at which point I lost all electronics - gear light was gone, DIM was gone, and signal lights not working - but the engine was still running and I was able to accelerate / brake just like normal. However once cleared of the traffic jam I had to pull over (without being able to signal...!) to switch off and on ignition - which gave life back to all electronics - only to get the same 'brake failure stop safely' message again within a couple of minutes...

Luckly when the above happened I was close to home - still had to stop / switch off/on ignition 4 times to get home - and did all this with our little baby aboard!! I remained calm and get us back home safely eventually.

Some FACTS:
- Starter motor, starter switch and ignition barrel was changed in Feb 2017 (by previous owner)
- Brakes were serviced late last year (by a good local shop) - all working fine
- I've recently disconnected ECM/TCM and reconnected them - car did two trips afterwards - both fine
- The aforementioned problems started with ignition playing funny - then 'airbag' warning message - then 'brake failure' warning message - then loss of all electronics.

my SUSPICION:
- The car had been stuck in bad traffic before (albeit just for a few minutes - not as bad as today's) and was fine
- the only thing had changed was ECM/TCM disconnection/reconnection - could I have messed up something with my amateur job?

Any help / advice would be greatly appreciated.

Thank you in advance.
Namo Amituofo

[abscate]

You really need the VIDA package to diagnose complex problems on the P2 chassis - multiple failures like this are usually not a lot of failed parts, but the parts are too expensive to guess and play 'parts darts'

If you don't get the eCM TCM back in right the car won't go very far, so move away from that diagnosis.

I dont understand what the 'ignition clicking' means, though. Need help there to help.

[leoxdeng]

Thank you guys - re 'ignition click' - when engine has been idle for a while it goes much quieter to almost quite - then a small 'click' sound and then engine runs louder again - I've always had this with the car while waiting to pick up people - and thought it was normal / by design... or have I got it wrong?

Going to first try cleaning contacts in ECM/TCM and also order a vida in case cleaning alone doesn't solve it.

Cheers
Namo Amituofo

[abscate]

Is this just the AC compressor cycling ?

Turn off the AC button and advise if the click stops

[leoxdeng]

Here is an update - I just cleaned contacts in ECM/TCM (noticed the ECM purple plastic holding tabs have almost 'rounded' where the ECU removal tool inserts - so suspect it was removed multiple times before mytime).

Upon reconnection battery, turned key to position II - still had engine light, engine light, and ABS light on. Turned key to ignition - all these lights were out. I then drove around the neighbourhood (up to 30 mph) - no problems.

What I don't know is - if the problems would recur - if so I'm almost certain can rule out ECM/TCM connector issue - as these are in top condition - no corrosion whatsoever - yet I still gave them a good cleaning today.

So will drive on a bit to see if problems recur.

Will follow up as and when.

Many thanks all - I really appreciate it!

Namo Amituofo