Recently I purchased a 2006 XC70 that has a no start condition (Start Prevented warning on DIM, no crank) from a family friend. I purchased a brand new battery first as it had been sitting for a while and had a battery low voltage warning on the DIM when purchased. Went ahead and did an oil change to make sure it was topped off and got a fresh set of spark plugs as I had an extra set laying around. With that I confirmed that the motor was turning freely by jumping pins 30 and 87 on the starter relay and from there got to work on inspecting the wiring and general health of the components in the engine bay. Once I had ViDA setup on a laptop and a VXDIAG unit to read the vehicle with, I started digging into the codes and live data.
First I went to the delivery tab within fault codes and found the following:
BCM-0065 Stop (brake) lamp switch Signal outside its permitted range
CCM-0004 Passenger compartment temperature sensor Signal too high/Signal missing
CEM-6C48 Transponder Type Faulty signal
CEM-9C03 Antenna/light ring Signal missing
ECM-710B Immobilizer communication – Signal missing
REM-4F42 Parking assistance sensor 1 Faulty signal
REM-4F43 Parking assistance sensor 1 Faulty signal
REM-4F44 Parking assistance sensor 1 Faulty signal
REM-4F45 Parking assistance sensor 1 Faulty signal
CEM-3F82 Immobilizer signal Signal too low
CCM-DD15 Damper motor, temperature left No communication
CCM-DD16 Damper motor distribution No communication
CCM-DD31 Damper motor, recirculation. No communication
CCM-DD32 Damper motor, temperature right No communication
CCM-DD33 Damper motor, defroster No communication
DDM-E010 Control Module Internal fault
DEM-000A Power supply Faulty voltage
PDM-E010 Control module Internal fault
Given all of that, the bold codes were the ones that stood out as potential causes to me for the Start Prevented issue and there certainly is more to take care of after that 😅(primarily DEM-000A as I believe that is the AWD unit). Once I saw these codes I immediately went to the local junkyard as I had seen a 2006 V70 arrive just the day prior that would be a perfect candidate to salvage an antenna ring and brake light switch from. With a quick resistance check reading properly, I purchased both and installed them when I arrived home. I was surprised to see that when I updated the scan on ViDA I found that all of the codes above were still present!
With that I went into the live data to get a better understanding of what was going on. I went to the CEM, and found the following between both the CEM and Immobilizer sections:
CEM-Key Type Main Key
CEM-Key number 1
CEM-Number of keys 0
CEM-ID code received Yes
CEM-ID code stored Faulty
CEM-Immobilizer, engine co… Wrong Status
CEM-Immobilizer, start per… Start not approved
In addition to these live readings, I was also able to get live data for the brake pedal through the brake pedal position, and pedal velocity. I do get lights in the rear when depressing the rear brakes however im unsure if this rules out a faulty brake switch sensor for the BCM-0065 code. I am new to the P2 platform with this vehicle but from what I have been able to find so far it would appear to me that the CEM could be faulty here and not the units surrounding it, maybe due to the low battery voltage or a possible spike in voltage from the previous owners efforts to diagnose the vehicle.
If the CEM did somehow lose its data regarding the stored keys, is there any way to recover that data and restore the CEM in that way? Or potentially even transfer that old CEM data to a functioning unit? Besides that, what would my other potential steps forward look like besides taking the vehicle to the dealership?
I really would appreciate it if anybody with more experience with the P2 chassis could help point me in the right direction here. My goal is to get this car back on the road running strong to eventually take over as my daily driver. For now I’m just taking this one step at a time and I see the first step as getting the electronics fixed and the motor cranking from the key. From there I can tackle any issues the motor has and the AWD system. Thanks for taking the time to read, I appreciate it!