XC70 Immobilizer, won't start, not antenna/CEM/ECM
 

My 2007 Volvo XC70 has been unusable for about six weeks now. I took the car to the local import repair shop to work on a fault with the stability control system - it was shut off and wouldn't turn on, and also brakes/axles/control arms. The shop determined the stability control problems was just a fuse, they fixed that right away, but had the car another 6 days to do the rest of the work. They took car for test drive after the work and a mile out the engine cut out with an immobilizer warning and hasn't started since. I feel like it has to be a coincidence that the problem occurred while the shop had it...since they did no electrical/engine work...but who knows.

The shop spent a few days working on it with absolutely no idea what to do. None of their OBD2 sensors could connect to the car. My Vida/DICE doesn't connect either (I tested it before and it worked). If I do a lock/unlock 5x sequence the engine will crank but it won't start. Gives an immobilizer-see manual warning. I replaced the antenna key ring and no difference. Figured it must be the CEM, so I sent the CEM/ECM/Key to Xemodex and they found no faults.

Xemodex is now recommending I disconnect the Differential Control Module DCM and if there is a fault with the DCM the engine will start. And if that's the problem Xemodex can fix that. I'll try that, but it seems very unlikely since how would the DCM prevent VIDA/DICE connection?

I guess it could be a problem with the key itself? Unfortunately the closest dealer is about 250 miles away, so that's a costly tow, and I'm told only the dealer can make a new key.

Is it possible to send the key somewhere to have the transponder tested or potentially cloned? Anyone have any other ideas for things to test?

Thanks for any help!

As these cars age, the cost of repairing systems like this will put them in the junkyard. In my opinion, the immobilizer should be able to be turned off after the vehicle reaches a certain age. No one is going to steal a 2007 Volvo wagon.

However, your lack of communication is likely due to the inability to transmit or receive a signal on the CAN BUS. Yes, a failed module can interfere with the signal. Try disconnecting the Haldex and see if it will start.

Tried disconnecting DEM and the fuse for the AWD and still nothing. Same immobilizer fault.

You are going to need a scan tool that can access all of the modules. For instance, I use a Snap On Solus for those vehicle years and it can read and display data on each module.

Without the scan tool and access to data and fault codes, you are just guessing. The good news is that you have the Volvo software and have a clue as to the vehicle's issue.

My guess here is that it is something simple, but no clue where to start.

With an immobilizer problem, I would start with a key but I don't think that they can make a key without the vehicle present to program same.