Two electronics problems in S70: voltage drop and doors central lock

Discussion in 'Volvo S70' started by Dmitry K., Apr 22, 2004.

  1. Dmitry K.

    Dmitry K. Guest

    Hey people,

    I've found two problems in my Volvo S70:

    1) The voltage drops, so when you ride in the night with your head
    lights on you can see them fade rapidly then getting lighter, the
    nfade again, etc. It looks like the battery has been replaced.

    2) Central locks wouldn't work in three doors: it would be able to
    lock each of them but wouldn't be able to unlock. I was told it's very
    likely to be the solenoids in the doors.

    Has anybody faced with the above problems? If so, I would really
    appreciate any type of advice/hints/tips on that (what could cause it,
    how much woud it cost to repair, etc.).

    Thanks a lot!

    Dmitry K., Apr 22, 2004
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  2. Dmitry K.

    Bonnet Lock Guest

    In an earlier contribution to this discussion,
    The two problems may be related! For the central locking to work properly,
    the battery needs to be in a good state of charge. If the alternator is
    playing silly b's (which could explain your lighting problem) the battery
    may not be getting fully charged.

    You could try charging the battery OFF the car and then seeing whether the
    central locking is ok. If it is, you need to concentrate on the charging
    circuit. If the central locking *still* doesn't work with a fully charged
    battery, the solenoids could be at fault.

    Although I suspect that the lighting problem is due to fluctuations in the
    alternator output, it *could* be caused by a bad contact in the lighting
    wiring - which maybe recovers a bit when you drive over a bump in the road.

    Does everything else continue to work ok when the lights go dim? Does the
    starter motor always turn the engine over at a good speed?
    Bonnet Lock, Apr 22, 2004
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  3. Dmitry K.

    Kytis Guest

    Don't know about the problem #1, but I definitely had a massive headache
    with my V70. Rear doors and the hatch, fuel gauge and some rear lights
    occasionally became disabled. After driving a few kms, all systems just
    recovered by itself. May I add, that it was most annoyning when you came
    back to your car after driving a few kms and the rear doors just didn't
    unlock. With a screaming kid it's not very pleasant ;)

    I was finally able to take the car, 2001 yearmodel btw, to the garage
    here in Berlin. And believe it or not, it was just a software that
    needed to be upgraded. The fix did cost a whopping 14 cents and there
    has never been a problem since. Talk about the minor fault...


    "Isän tärkein tehtävä on kasvattaa tyttärensä niin
    ettei hän huoli paskaa jätkää miehekseen"
    Kytis, Apr 22, 2004
  4. Dmitry K.

    Myron Samila Guest

    I would have your alternator tested and repaired asap. If the regulator were to become
    failed in the shorted position, you could easily have an overvoltage situation, which at
    the least blows lamps, at the worst, destroys ECUs and such.

    The door lock solenoid is an easy fix, possible something is not allowing it to open
    properly/close properly (need of lubricating all the points in the mechanism), or simply
    replacing it.

    The #1 problem is more important, a bad alternator can also ruin a battery.
    Myron Samila, Apr 23, 2004
  5. Dmitry K.

    jcm Guest

    The door lock problem is not the selonoid, it is the red thing in the lock
    mechanism that breaks off when a passenger is trying to open the door while
    the driver is unlocking the doors. The only door of yours that works is the
    driver door. Go to for step
    by step instructions to repair the trigger to unlock the doors. The only
    other alternative is to buy a whole new unit for about $300 each.

    jcm, May 4, 2004
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