BCM-0094 & CEM-1A64 is a bad BCM.
BCM-0094 & CEM-1A64 is a bad DEM.
For a bad BCM:
For a bad DEM:
From HaldexRepairs.Co.Uk they claim about halfway down this page: Volvo Guide to Haldex fault finding, ECU repairs and replacement – Haldex Parts and ECU Repairs by Auto Fault Finder Ltd,
“Faulty Haldex ECU’s always cause the CEM-1A64 and/or BCM-0095 and/or BCM-0094 faults because the unit is not talking to the rest of the car. We can repair these units. Buy Haldex ECU Repair Service Here“
ViDA seems to only describe the issue as something wrong with communicating with the DEM (no power, bad connection, wrong programming).
What I think:
My car is a 2004 S60R.
I think it’s pointing to the DEM. I have no other codes for the BCM and in ViDA I can identify the BCM, but not the DEM.
XeMODeX claims here that just a CEM-1A64 code can mean a bad DEM. It looks like in this situation the CAN bus circuitry would be to blame and would cause the DEM to not be seen on the bus. IT could either hang on the bus and cause lots of communication issues and not found devices, or simply make the DEM missing from the bus.
In my situation I cannot find the DEM on the bus, but the BCM seems to be just fine. I can query it for data and get that no problem. The bus communication means that it is not dependent on the BCM for communication, so it would seem like it’s not on the bus. I have tested for power and ground at the DEM.
A little more history, this worked about 8 years ago until I decided to pull the fuse because my tires were wearing unevenly and I decided to save the pump until I mounted the new tires. Then I parked the car for 7 and a half years because I was going to build an engine and life got in the way.
So now I built a new engine and I’m surprised that the AWD has quit. I’ve tested the pump, it’s got 2 ohms of resistance, and does not blow the fuse. I thought I read somewhere that it should be about 4 ohms, but I cant find that information. I do know that the parts rear diff I have (also from a manual 2004 S60R) had 40 ohms on it’s motor. A bad one I checked in my mom’s XC70 had more than 1K and it was blowing a fuse. I’m not sure why the high resistance would blow a fuse, but it probably has something to do with the driver circuit. I did an a new filter and oil service on the Haldex probably 5000 miles ago too. So I swapped the DEM and there is no difference.
There is a chance that these both have failed in the same way, but I decided to see if mine had water intrusion or a blown transistor for the motor.
Well, this thing is clean. Nothing looks cooked and no signs of water invasion. The CAN bus translator chip is boxed in blue. The red is the driver for the solenoid valve and the green is the motor transistor. That’s the one that a bad pump can possible take out. It looks like both of those have a current monitoring resistor next to them. On the back side there is only a parallel flash memory chip, that probably contains all the user code (Volvo) that runs this module, and the plugs and seal for that penetration. But it all looked like water has never made its way inside this module, so it’s looking like that’s not it.
I haven’t verified with an oscilloscope that I’m getting a good signal to the module, but besides a bad connection, anything else affecting the bus, should affect more. Unless there is some special relationship between the BCM and the DEM that I don’t understand.
I haven’t tried unplugging the motor and I may try that next, but I would think that the motor should only be able to cause an issue if the transistor is shot thought, but there was not tell tell smells of the magic smoke being released too.
One ore thing for the BCM; when I pulled the engine out all those years ago, I pulled it out the top like a fool. I thought I got the transmission caught pretty good on the BCM. I didn’t see any cracks or real evidence of that and I’ve also puled several of these out the top in the junk yard, so I just cant rememeber. If I did disturb the press fit contact pins and cause an issue, that could have done it. However, I am of the mind that I would cause mode BCM related issues and not be able to talk to it if I damaged it and it seems to be just fine.
I’m here seeing what others may know, but also, when I get to the bottom of this I hope to be able to guide some people in the right direction.