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  1. #1
    Join Date
    Aug 2019
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    Default XC70 Electrical Failure

    I own a 2008 XC70. We parked up for just a few hours then got back to the car and opened her up on the remote, put the key in and absolutely nothing.
    We put a battery booster on and after a few minutes we did start the car, there are no dashboard lights or instruments, nothing which is powered works ( seats/windows/rear hatch)
    I travelled 80 miles and the drive was uneventful but still nothing powered worked, I then switched off . Upon switching on again he car is totally dead again
    Any thoughts please?

  2. #2
    Join Date
    Dec 2009
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    Default

    Probably just a bad battery, how old is it? Sometimes they fail all of a sudden instead of giving weak battery symptoms for a while.

    You drove 80 miles after jump starting which tells me the alternator is charging enough to keep the car running.

  3. #3
    Join Date
    Aug 2017
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    Pleasanton CA USA
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    Default

    This indicates that either the battery is toast, or you have a short circuit somewhere draining the battery after shut-down. You can test for a short: Charge up the battery with an external charger, then 5 minutes after removing the charger, disconnect the negative battery terminal. If it makes a noisy spark, then something is drawing too much current in the car's "sleep mode", e.g. likely a solenoid or motor is stuck "on".

    If there isn't any big spark, you just have a failing battery.

  4. #4
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    Aug 2019
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    Default

    Quote Originally Posted by pbierre View Post
    This indicates that either the battery is toast, or you have a short circuit somewhere draining the battery after shut-down. You can test for a short: Charge up the battery with an external charger, then 5 minutes after removing the charger, disconnect the negative battery terminal. If it makes a noisy spark, then something is drawing too much current in the car's "sleep mode", e.g. likely a solenoid or motor is stuck "on".

    If there isn't any big spark, you just have a failing battery.
    Thanks for this, there isnt a spark if I try this. I have now put a new battery on and the car starts and runs but still I have no dashboard instruments or lights and no drivers side window or seat electrics. Also little things like the parking/ proximity sensors arenít working or rear tailgate electric raiser,but wipers and radio and passenger side windows do, a bit odd!
    Update - the key will now not come out of dashboard

  5. #5
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    Default

    I think the next step is to hook up an OBD-II scanner, and see if any software is detecting a problem, e.g. communication between modules, or 12V power absent in a subsystem. Someone else might inspect the fuse banks, but that's for later if the ODB-II scanner yields no useful info.

  6. #6
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    Dec 2009
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    Quote Originally Posted by Stevesvolvo View Post
    still I have no dashboard instruments or lights and no drivers side window or seat electrics. Also little things like the parking/ proximity sensors arenít working or rear tailgate electric raiser, - the key will now not come out of dashboard
    Sometimes the CEM will turn systems off to save current for the car to run when the voltage gets low. You might try rebooting the car - disconnect battery, hold terminals together (to drain capacitors in control units) for a couple of minutes, reconnect and see if stuff starting working. I have seen many cases where existing trouble codes will need to be cleared with VIDA or a compatible scan tool before systems will work again.

  7. #7
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    Default

    As a sanity check on 12V power distribution, you could test for 12V at some of these fuses in the rear cargo area:

    Power Operated Tailgate Module
    Drivers Door Module
    Power Seat Module

    with the engine running. These functions were mentioned as not working. If there is good 12V power at these fuses, then
    the functions are likely being inhibited in software. Try the cold electrical restart described in the previous post.
    Click image for larger version. 

Name:	rear compartment fuses.jpg 
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  8. #8
    Join Date
    Aug 2019
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    Default

    Quote Originally Posted by pbierre View Post
    As a sanity check on 12V power distribution, you could test for 12V at some of these fuses in the rear cargo area:

    Power Operated Tailgate Module
    Drivers Door Module
    Power Seat Module

    with the engine running. These functions were mentioned as not working. If there is good 12V power at these fuses, then
    the functions are likely being inhibited in software. Try the cold electrical restart described in the previous post.
    Click image for larger version. 

Name:	rear compartment fuses.jpg 
Views:	5 
Size:	72.1 KB 
ID:	9027
    Just to finish this tale off I took the car to a main dealer who did a diagnostic. The whole issue is caused by a cheap battery having been put on the car by a previous owner which had cell failure so causing a effectively a short. It was only holding/accepting 7% charge. If I understand correctly this caused the alternator/ electrical system to be selectively closing down systems such as powered seats , windows, dash instruments, blower fan , tailgate, but leaving essential bits working. £130 later and all is well.

  9. #9
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    Steve, thank you for posting a final chapter -- those are the most valuable posts on VolvoXC.

    I'm left with just one question. Was there ever any message or icon on the console indicating an electrical problem?
    Last edited by pbierre; 08-14-2019 at 08:02 PM.

  10. #10
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    Default

    Quote Originally Posted by pbierre View Post
    Steve, thank you for posting a final chapter -- those are the most valuable posts on VolvoXC.

    I'm left with just one question. Was there ever any message or icon on the console indicating an electrical problem?
    None at all. Car started perfectly in the morning, no sign of a failing battery as I would have expected. Drove 80 miles or so into London then left the car a couple hours. Upon my return it was completely dead. Fortunately I carry a better booster so could start it.

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