412i Battery Drain - Turn Signals When Switched Off | FerrariChat
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412i Battery Drain - Turn Signals When Switched Off

Discussion in '365 GT4 2+2/400/412' started by jhkm12345, Oct 22, 2025 at 8:56 AM.

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  1. jhkm12345

    jhkm12345 Rookie

    Mar 17, 2015
    21
    Atlanta, GA
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    John M
    #1 jhkm12345, Oct 22, 2025 at 8:56 AM
    I've done quite a bit of digging on the forum and have come across a few posts relating to turn signal repair, but not so much their appropriate function.

    I'm chasing down a draw on the battery and am suspicious that it is somehow related to the fact that the turn signals are functional with the key turned off.

    Can anyone confirm or deny that the turn signals should come on or illuminate steady with the key turned off?
    This is a 1987 Euro 412i

    Also, any sources or shared wiring diagrams would be greatly appreciated!
     
  2. SouthJersey400i

    SouthJersey400i Formula 3

    Mar 14, 2007
    1,683
    Romulus, NY (Finger Lakes)
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    Ken Battle
    #2 SouthJersey400i, Oct 22, 2025 at 10:14 AM
    In Europe and on many Euro cars, when people park on a street at night, they leave the outside turn signal on and it does not flash when the key is off. Maybe the Euro 412's had that feature, but it WILL run down a 412 battery overnight.
    I solved a battery draw problem by putting an ammeter on the main battery cable. I saw a small but significant draw with everything OFF. I pulled the fuses one at a time and found the draw was from the rear window defroster switch/wiring which was disconnected when a new rear screen was fitted (by a prior owner). Disconnecting the switch did the trick. You will need a good ammeter to do this check.
    Ken
     
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  3. jhkm12345

    jhkm12345 Rookie

    Mar 17, 2015
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    Atlanta, GA
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    John M
    #3 jhkm12345, Oct 22, 2025 at 12:04 PM
    Thanks, Ken. Yes, I am familiar with some euro makes/models leaving a marker light on when the key is off and the signal switch is engaged. Not sure what the rationale is for that, but I get it! Curious if this is the case on the 412 though. My signals and hazards are all operating as they should, with question of signals working with key off.

    I have already pulled each fuse and relay, individually, to find no impact on draw. I'm chasing a ghost - likely a short or damaged wire somewhere along the way.
     
  4. raemin

    raemin Formula 3

    Jan 16, 2007
    2,400
    Lyon (FR)
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    R. Emin
    #4 raemin, Oct 22, 2025 at 2:48 PM
    As the turnsignal relay is used for the warning, its powersupply must come from a permanent power supply (not an acessory supply).

    You could use an ampmeter in lieu of a.fuse is norder to identify parasitic power draw.

    Courtesy lights (including in the trunk) can deplete the battery if the switch is not properly locked when the lid is closed.
     
  5. Steve Magnusson

    Steve Magnusson Two Time F1 World Champ
    Lifetime Rossa

    Jan 11, 2001
    26,972
    30°30'40" N 97°35'41" W (Texas)
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    Steve Magnusson
    #5 Steve Magnusson, Oct 22, 2025 at 8:28 PM
    Have you checked your "Conversations"?
     
  6. jhkm12345

    jhkm12345 Rookie

    Mar 17, 2015
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    Atlanta, GA
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    John M
    #6 jhkm12345, Oct 23, 2025 at 8:28 AM
    I have and just replied. Thank you for your thoughts and recommendations.
     

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