2014 XC70 DSTC / PAM errors
 

Hi all,

I hoping someone here maybe able to assist. Apologies if some items below are not completely AWD related.

Last week, whilst driving, I received a 'DSTC Service' and 'Parking Assistance service' warning on the information screen. These both came on at the same time.

I parked up at my destination and on restarting there were no further errors until 2-3days later when they showed again and are now permanent, even after disconnecting the battery.

I've plugged in my vida dice and the network is showing red failed communication from the DEM and PAM. Other links are all green.

The error codes logged are listed below.

CCM-B103087 Left front seat heater - bus signal / message failure - missing message
CCM-103287 Right front seat heater - bus signal / message failure - missing message
BCM - U013600 Lost communication with DEM rear
CEM - U013600 Lost communication with DEM rear
CEM - U015900 Lost communication with PAM
CVM - U041568 Invalid data received from BCM - Algorithm based failue - event information
DIM - U015900 Lost communication with PAM


My plan this weekend is to check the DEM and PAM for 12v and any resistance in the communications link.

Apart from that is seems unlikely that these errors are not all linked to one item. The passenger seat & heater rarely gets used so a problem with this seems unlikely.

If anyone has a recommendation for the best approach on which items to check first I would be grateful.

Regards, Steve

Did you clear the codes and see what ones returned?

Hi,

The codes listed are the ones that remain after 'erasing all'

I changed the haldex oil and cleaned the pump sock (70% blocked) about 3months ago and all was well until last week.

My searches for haldex 5 dem problems don't return much.

Hopefully I can fix the awd before the weather turns

Thanks, Steve

Hi,

I'm looking into the problem today and have found there there is no 12v power supply to several fuses below the glove box.

#26 - Seat heating passenger
#27 - Seat heating drivers
#28 - Parking Assistance
#29 - AWD control module

Oddly enough, these fuses are all in a line on the RHS bank of the fuse box.

What would be the next course of action. I wasn't hoping to resolve this without going to the dealer.

Regards, Steve

Strange that you should lose power to that bank of fuses. I wonder what controls the power to that circuit.

Does Vida show a master supply and fuse? to that bank of fuses..

Could there be a broken earth path wire for that circuit?

I don't seem to have the wiring diagrams on my vida software. I will need to see if I can find this and trace the problem.

I did find a post on a search where someone had a similar problem with the AWD/PAM fault; unfortunately there was not follow up on how it was resolved.

Regards, Steve

Unfortunately you will need someone other than me for a definitive answer, someone who is well versed in canbus systems.
However I do know from experience that it doesn't like noise or interference as this disrupts the signals sent and received. This can be as simple as a pin connector that is not as tight as it should be or corrosion in a terminal. A broken wire going to earth could also be the culprit. I've read threads of XC60 owners who located fray cables near the alternator.

It is also well documented for P3 V70/XC70 that there have been instances of water ingress corroding the terminal block of the CEM causing all manner of error codes.
Might be prudent to disconnect the CEM and check each pin. Don't forget to disconnect the battery and give it a while to discharge before you do or you'll trigger loads of other error codes.

Voltage is also very important. Canbus doesn't like voltage drop. Check at the battery what you have.
I've also read threads where people have replaced a tired battery and cured their issues.

Best of luck. Lettuce snow how you get on.

Cheers

Dave

Hi Dave, thanks for your post. Nice car and good colour choice you have there :-)

I managed to locate a wiring diagram late yesterday evening and have traced this bank of fuses to relay R1 which is positioned above the fuses.

As it was late, I have yet to remove this relay to test the switch and continuity but if seems highly likely that this is the culprit.

I will update once I've checked the relay later today. All going well I will have my AWD and traction control back shortly, along with heated seats and parking sensors.

Have you changed the haldex oil & gearbox oil in your xc70 yet.

Regards, Steve

Cheers. I like silver. Seems to stay cleaner for longer.



I had the Haldex pump fail under warranty at 48k miles so fluid change along with the pump.
I am fortunate that the technician at my Stealership is a fellow XC70 owner and enthusiast.

Yes do please update. As you have found yourself there are so many threads left without posting about how the issue was resolved.

I've solved the problem today :teeth_smile:

Working back from checking for 12v power at the modules led me to the fuses under the glove box. All the fuses were ok (not blown) but having no 12v power to some fuses didn't immediately occur to me but that is what I found on the right hand side fuse bank; no power!?! I worked out that the fuses without power all led to the modules and systems that were showing in the vida fault diagnosis.

My next course of action was to check the power supply routes to the fuse box by looking at the wiring diagram. This is part of vida if you have the EWD but my version didn't have this so I searched on line and manged to locate a 436 page .pdf file with comprehensive wiring diagrams. By page 14 I found what I needed and could see that the bank of fuses was being fed 12v power from a relay 'R1'.

I removed and tested the relay and found a fault with the switch. A new relay from Volvo fitted and problem now solved. I've erased all the errors using vida and taken the car for a test drive and all is good. Parking sensors and heated seat back on along with DSTC and AWD.

I hope this conclusion helps anyone with similar issues.

Regards, Steve