BCM failure and symptoms 2008 XC70 Topic is solved

Post by **precopster** » 26 Oct 2018, 05:52

Had a 2008 XC70 land here yesterday on a flatbed. No start signal. Immobilizer message on dashboard. Brake system failure as well.

Scanned with Vida and many CEM codes which relate to communication issues. You can see some window & mirror problems (DDM and PDM) however they all work fine.

Network image shows that the BCM is offline. Probing the 2 power leads to BCM with ignition switched on shows they are powered. Chassis were also checked. Reseated the BCM connector which is clean as a whistle

Discovered that the BCM has immobilizer information so this module needs replacement at a dealer. It can't be cloned because it has a faulty power stage on the board stopping it from displaying immo info and network status.

Cost over here will run to around $3,500 including fitting and software download with the BCM coming in at around $2,500 (in the USA it's over +$1,250) We shopped around for that price. One high profile dealer wanted $4,150 just for the BCM !!

The BCM comes with the ABS pump attached.

I don't think I want to own a P3 right now......

Post by **oragex** » 26 Oct 2018, 07:17

Immobilizer information on the BCM ?? What is Volvo thinking?

That said, I'd still try a used one, before sending the guy to Volvo. By the past Volvo said on many modules they can't be swapped or they need programmed. Just a try before the cry.

And I'm also a bit paranoid about the Volvo network faults, I'd rather try the more 'standard' things before replacing a module

Was the car battery drained prior to this issue?
a P3 with battery drain and immobilizer problem https://forums.swedespeed.com/showthrea ... again-quot

Here's another P3 with a shut off and immobilizer message (unfortunately not solved)
https://volvoforums.com/forum/2001-2013 ... ecm-95928/

Also this video but on P2
www.youtube.com/watch?v=mhNawwOORiM

Post by **precopster** » 27 Oct 2018, 00:57

No faults existed on the car until a few days ago when the car was idling for 30 minutes for owner's wife to pick up kids at school. Car died while running and would not start. As we can't crank the engine we can't get readings from alternator, however it arrived with 11.5V on the battery due to the amount of times the owner attempted to start it.

Battery was disconnected by me, fully charged and reconnected and correct re-connection procedure for P3 was employed.
Dash display shows immobilizer message with fully charged battery. I might add that I was the 2nd person to attempt to repair this vehicle. First was a Volvo specialist who blamed the CEM however I performed a full Vida diagnostic check of the CEM and it passed all tests. The first garage also disconnected and reconnected all CEM connectors hoping for a connection problem. I was surprised they didn't/couldn't see that the BCM was offline and also that they weren't aware of BCM's immobilizer role. They didn't have Vida and I was given their diagnostic report which was from a different type of system.

BCM is not present on the network. I was told about the BCM containing immobilizer info by Henry. He would have been happy to swap in another BCM and clone it if only we could READ the original.

This is only the case with P3s as the earlier cars employed the module ending in xxxxxx224 and these would not have an effect on immobilizer as far as I know, unless they began doing this in 2007 as a tester for the next generation. That thread on Volvo Forums was for a 2007 so I doubt it was a P3.

Henry suggested I put in a used BCM and tow to the dealer for a BCM reload however the location of the BCM hard against firewall means it has to come out with the pump and disconnection from hydraulics. I figure 4 hours of labour to bleed system PLUS the used part and it's very quickly a $600-700 gamble. Also dealer would have seen system was disturbed and may not play ball.

Post by **RickHaleParker** » 27 Oct 2018, 03:35

You confirmed power, ground and CAN to the BCM?

Post by **RickHaleParker** » 27 Oct 2018, 03:55

oragex wrote: ↑26 Oct 2018, 07:17 Immobilizer information on the BCM ?? What is Volvo thinking?

I cannot say what the Volvo engineers where thinking but I can say the cost of managing part numbers is an incentive to combine two units into one.

Back in the 90s we figured out that the old paradigm: a fraction of a cent per part less adds up to more profit, is no longer true. It is better to pay more for a one size fits all part then pay the overhead of managing a bunch of part numbers.

Post by **precopster** » 27 Oct 2018, 05:47

Power and ground were confirmed. There can be no Can visible if module has chronic failure. I've seen this with ETMs and DEMs thus far. I have a box of ETMs that are not visible on Can and another box that are visible.

Where Can is not visible it's a different type of fault where the Can controller itself has failed or has no way of reporting itself to the network due to unknown reasons.

I would say it's a way to enhance the safety of a vehicle. If the BCM has intermittent fault then it's safe to drive to an extent but if the BCM has total failure, traction control and ABS anti-skid functions are both non-present; not exactly the type of vehicle Volvo wants us to get into accidents, so preventing startup is a logical route for their safety regime and reputation.

Post by **RickHaleParker** » 27 Oct 2018, 06:32

You might call these guys and see if they can bring dead things back to life. G7 Computers. Flat rate Volvo Control module repair $275.00. Free testing. If they can fix the hardware you won't need a software reload.

Post by **oragex** » 27 Oct 2018, 06:44

precopster wrote: ↑27 Oct 2018, 00:57 No faults existed on the car until a few days ago when the car was idling for 30 minutes for owner's wife to pick up kids at school. Car died while running and would not start. As we can't crank the engine we can't get readings from alternator, however it arrived with 11.5V on the battery due to the amount of times the owner attempted to start it.

I thought the starter would not engage if the immobilizer went off? So if the car died on her, then she tries starting it and cranks until the battery goes to 11.5v then the first reason the car died is not the immobilizer because the immobilizer would prevent the starter from turning.. I feel like the initial problem is something else, plus then she drained the battery which engaged the immobilizer.

Can the engine be cracked by powering the starter? I have a little thought about the tb

Just flexing my brain a little

How many miles on it?

Post by **precopster** » 27 Oct 2018, 07:04

Thanks for the link Rick but owner would rather spend the dough than wait weeks for 2 way postal service without a guaranteed fix assured.

I didn't say that engine cranks. It can't crank because starter relay has not been energised by the BCM. This is confirmed by wiring diagrams on 2008 XC70. This is actually a diesel.

Attempting to start it multiple times leaving ignition on draws a lot of current especially if you leave ignition on for 30 minutes or more.

As I mentioned it arrived here after another shop had a decent diagnostic session with it however they didn't bother to charge the battery before releasing the car.
I'll report back once the car is repaired by the dealer as my involvement has stopped.

Post by **oragex** » 27 Oct 2018, 07:44

Keep us updated!