Antiskid + Brake failure stop safely - Error expert needed!

[danc]

Hi all, I've still got the problem outlined in my earlier post: http://www.volvoforums.org.uk/showthread.php?t=208362

In short, my 2006 Volvo XC90 is intermittently (twice this week) showing:

• Antiskid service required
• Brake failure stop safely
• Limp mode
• Stuck at zero - speedometer, rev counter, engine temp gauge
• - in the gear mode (not D, R, N etc...)
• After the above and the engine switched off, it won't then turn over for at least an hour

I've had the codes read by my local independent Volvo garage - see photo.

There's a mass of DTCs on the print out, with all but one currently reporting A-Ok. The brake pedal sensor was initially reporting a problem during the test but was somehow cleared by the technician.

Using the print out, can anyone offer any advice? My next step is to get the garage to check the CEM (water ingress was apparently a problem on earlier XC90s but fixed in my model).

[Clan]

A lot of communication problems there , which may have been there a long time and caused by a flat battery or someone disconnecting plugs etc . Ignore those for now ,
The brake position sensor on the servo needs changing thats an active fault ,
also a SAS ( Steering angle sensor ) software upgrade is the first thing to do with that code . clear all the codes and fingers crossed .

[danc]

Thanks Clan, the codes were reset a couple of weeks back. Definitely some sort of comms issue going on.

Since then, I did disconnect the battery for a couple of minutes to try and kick it out of limp mode one time - didn't work, probably should have waited longer.

I tried cruise control while in limp mode, which could have given the cruise error code. I guess trying to restart the engine could have thrown the immobiliser code.

Not sure if it's had the SAS software update yet but will mention that to the garage. I've seen it mentioned elsewhere. Really good point. Ditto on the brake position sensor.

[danc]

Latest update:

I had the brake pedal sensor (£100+ VAT) replaced yesterday but not the SAS software upgrade since the software was already up-to-date.

No "Antiskid" or "Brake failure" errors in the last 50 miles although obviously it's a bit too early to be sure - here's hoping...

[danc]

Since my last post a few days ago, the problem has arisen again....

For new readers:

• Lift foot off brake pedal (while in Drive and from always stationary)
• Clonk heard (like a noisy gear change)
• Antiskid service required
• Brake failure stop safely
• Limp mode
• Stuck at zero - speedometer, rev counter, engine temp gauge
• - in the gear mode (not D, R, N etc...)
• After the above and the engine switched off, it won't then turn over for at least an hour

As feared, replacing the Brake Pedal Sensor has had no effect.

The errors I had logged before changing the sensor can be seen here: http://www.volvoforums.org.uk/attach...5&d=1404562609

When the issue does arise, it's always as I'm lifting my foot off the brake pedal (moving off from stationary in Drive).

Does this sound like a DEM issue or a CEM issue? Or something else?

I understand the DEM can be disconnected by a fuse. I can live without DTSC and AWD for a while if it helps pinpoint the issue (e.g. if it's still happening with the DEM disconnected, I can rule it out). Is this possible and are there any other considerations?

Ideas and suggestions gratefully received!!

[SonyVaio]

Have you taken out the CEM and cleaned all connections? If not this is certainly worth a try, you have a lot of communication errors going on there (either past or present).

Once CEM connections have been cleaned on both plug and connector ends then I'd see how you get on, reset all codes if possible. If problem still exists then I'd next check and clean connections for ABS unit and reset codes again (if possible).

Following this it would be back to codes to see what has been logged since last reset and then I'd think you would be possibly looking at bit further electrical diagnosis prior to replacing parts. I would have the voltages checked from the CEM to the ABS unit to ensure wiring is fine and not broken and then you may be looking at ABS unit or CEM replacement.

Normally when the ABS unit is at fault it is code ECM0130 that exists.

[danc]

Thanks SonyVaio.

I've yet to find any decent instructions on accessing and removing the CEM. I understand you need to remove the windscreen wiper assembly to access the bolts that keep it in place. Is it a job for a competent DIYer or best left to a garage?

[danc]

Also, is it worth trying to disconnect the DEM fuse? Has anyone tried this?

[judgeman]

Had a similar brake issue on '05 90. Turned out water in CEM due to tge faulty bulkhead waterproofing.

Not sure about the other issues, but certainly worth getting CEM checked out, if only to rule it out (your car may have the upgraded bulkhead thingies).

[danc]

I think the 2006 model I've got is more immune to the water ingress problem (which means the issue is probably going to be harder than ever to track down).

The car is back in the garage tomorrow for an error read and CEM removal / inspection.