FRAMING JOHN DELOREAN - ON VOD www.framingjohndeloreanfilm.com
Page 1 of 4 1 2 3 ... LastLast
Results 1 to 10 of 33

Thread: 4amp draw- high pitched whine from engine compartment- ignition off

  1. #1
    Member gluaisrothaii's Avatar
    Join Date:  Sep 2019

    Posts:    90

    4amp draw- high pitched whine from engine compartment- ignition off

    Had a dead battery today. Drove the car quite recently- yesterday. Quick boost charge to start, alternator came up fine. Battery charged on a 30 minute drive.

    Post driving I shut down and heard a high pitched whine from the engine compartment. Not the CS, ISC or FV. Pulled plugs from those and whine and load remained. Ballast resistor was cool so not the coil. Connected up an instrumented power supply, disconnected the battery and saw a 3.8-4.1 amp consistent load along with the whine. Pulled fuses to troubleshoot-either 4, 10 or 16 eliminated the issue (or just coincidental timing) but the load was gone when I plugged the fuses back in. Didn't get to pull the WUR plug before the whine stopped, and the 4 amp load was gone.

    Any ideas?


    Best,
    Ken
    1981 DMC 12- Black
    VIN 46**
    Alameda CA

  2. #2
    Under Ron's watchful eye. Glory be to Ron! Michael's Avatar
    Join Date:  May 2011

    Posts:    4,098

    My VIN:    None of your business you creepy psycho vin counter...get a life

    Alternator is taking a puke. It can still charge and be burnt up. Most likely driving with a very low battery finished it off.


    Edit: oh this was after the engine stopped? Scratch the alternator if that's the case.

  3. #3
    Member gluaisrothaii's Avatar
    Join Date:  Sep 2019

    Posts:    90

    Quote Originally Posted by Michael View Post
    Alternator is taking a puke. It can still charge and be burnt up. Most likely driving with a very low battery finished it off.


    Edit: oh this was after the engine stopped? Scratch the alternator if that's the case.
    Alternator would be annoying. It's brand new from DMCH. 300 miles. Whine was there with the engine off.

    Just to clarify- alternator is topping battery off easily while driving, and running the lights etc, and the vehicle runs just fine. When turned off there's (sometimes) a real 4 amp electrical load that is depleting the battery. Something like a stuck relay. Whatever is consuming the power makes a high pitched whine in the engine compartment and doesn't show any signs of doing anything useful with the power.
    Last edited by gluaisrothaii; 12-25-2019 at 08:58 PM.
    1981 DMC 12- Black
    VIN 46**
    Alameda CA

  4. #4
    Senior Member DMC-81's Avatar
    Join Date:  Apr 2014

    Location:  Florida

    Posts:    2,201

    My VIN:    <2000

    Club(s):   (DCF)

    That's an odd problem. There is a relay below and to the left of the ballast resistors (see pic). Is yours present? If so, I would perhaps check that.



    I pulled that relay one time to do some troubleshooting and the car did not stall.

    Other than that, I wonder if your starter solenoid is slightly sticking (just a shot in the dark).
    Last edited by DMC-81; 12-25-2019 at 10:03 PM.
    Dana

    1981 DeLorean DMC-12 (5 Speed, Gas Flap, Black Interior, Windshield Antenna, Dark Gray)
    Restored as "mostly correct, but with flaws corrected". Pictures and comments of my restoration are in the albums section on my profile.
    1985 Chevrolet Corvette, Z51, 4+3 manual
    2006 Dodge Magnum R/T (D/D)
    2010 Camaro SS (Transformers Edition)

  5. #5
    Member gluaisrothaii's Avatar
    Join Date:  Sep 2019

    Posts:    90

    Quote Originally Posted by gluaisrothaii View Post
    Alternator would be annoying. It's brand new from DMCH. 300 miles. Whine was there with the engine off.

    Just to clarify- alternator is topping battery off easily while driving, and running the lights etc, and the vehicle runs just fine. When turned off there's (sometimes) a real 4 amp electrical load that is depleting the battery. Something like a stuck relay. Whatever is consuming the power makes a high pitched whine in the engine compartment and doesn't show any signs of doing anything useful with the power.
    By unplugging every other noise maker in the engine bay I have isolated the whine to the alternator. It whines with the ignition on, and stops when I pull the charge light connector out (brown/yellow vehicle wire). 4 amps would make sense for full field current. Why/how would the alternator turn on field current with the ignition off?
    1981 DMC 12- Black
    VIN 46**
    Alameda CA

  6. #6
    Senior Member
    Join Date:  Dec 2016

    Posts:    306

    Quote Originally Posted by gluaisrothaii View Post
    By unplugging every other noise maker in the engine bay I have isolated the whine to the alternator. It whines with the ignition on, and stops when I pull the charge light connector out (brown/yellow vehicle wire). 4 amps would make sense for full field current. Why/how would the alternator turn on field current with the ignition off?
    Check to see if + voltage on the brown wire going to the voltage regulator is turning off with the ignition switch. If you have power with the key off. disconnect the brown wire and test to see if the power is coming from the ignition circuit (brown wire) or feedback from the alternator thru the regulator. Power at the brown wire's alternator connector would indicate internal short in the alternator voltage regulator. Power on the brown wire would incriminate the auxiliary relay (It supplies power to the alternator regulator but should only be engaged when the key is on).

    Ron

  7. #7
    Senior Member Bitsyncmaster's Avatar
    Join Date:  May 2011

    Location:  Leonardtown, MD

    Posts:    7,938

    My VIN:    03572

    My guess would also be the alternator is bad. The 4 amp load does sound about right for the field current and the wine must be the regulator is switching that current on and off.
    Dave M vin 03572
    http://dm-eng.weebly.com/

  8. #8
    Member gluaisrothaii's Avatar
    Join Date:  Sep 2019

    Posts:    90

    Quote Originally Posted by DMC-81 View Post
    That's an odd problem. There is a relay below and to the left of the ballast resistors (see pic). Is yours present? If so, I would perhaps check that.



    I pulled that relay one time to do some troubleshooting and the car did not stall.

    Other than that, I wonder if your starter solenoid is slightly sticking (just a shot in the dark).
    Thanks- I had previously replaced that relay and it does not seem to be the source of the issue.
    1981 DMC 12- Black
    VIN 46**
    Alameda CA

  9. #9
    Member gluaisrothaii's Avatar
    Join Date:  Sep 2019

    Posts:    90

    Quote Originally Posted by DMC-Ron View Post
    Check to see if + voltage on the brown wire going to the voltage regulator is turning off with the ignition switch. If you have power with the key off. disconnect the brown wire and test to see if the power is coming from the ignition circuit (brown wire) or feedback from the alternator thru the regulator. Power at the brown wire's alternator connector would indicate internal short in the alternator voltage regulator. Power on the brown wire would incriminate the auxiliary relay (It supplies power to the alternator regulator but should only be engaged when the key is on).

    Ron
    Quote Originally Posted by Bitsyncmaster View Post
    My guess would also be the alternator is bad. The 4 amp load does sound about right for the field current and the wine must be the regulator is switching that current on and off.

    Hi Ron, Dave,
    With the 140 Amp DMCH alternator only the brown/yellow wire is used to trigger the regulator to turn on. This is the ground side of the charging lamp on the instrument panel. The brown wire from the aux relay is terminated inside the harness. Though it is not documented by DMCH, it seems to be optional to use the brown as a voltage sense line so that the VR drives to 14.8V at the battery rather than just at the B+ post of the alternator.

    As a test later on today I'll hook up a variable voltage source to the L input on the alternator to see what it takes to turn it on and confirm that it draws 4 amps in that state.

    Best,
    Ken
    1981 DMC 12- Black
    VIN 46**
    Alameda CA

  10. #10
    Senior Member DMC-81's Avatar
    Join Date:  Apr 2014

    Location:  Florida

    Posts:    2,201

    My VIN:    <2000

    Club(s):   (DCF)

    Quote Originally Posted by gluaisrothaii View Post
    Hi Ron, Dave,
    With the 140 Amp DMCH alternator only the brown/yellow wire is used to trigger the regulator to turn on. This is the ground side of the charging lamp on the instrument panel. The brown wire from the aux relay is terminated inside the harness. Though it is not documented by DMCH, it seems to be optional to use the brown as a voltage sense line so that the VR drives to 14.8V at the battery rather than just at the B+ post of the alternator.

    As a test later on today I'll hook up a variable voltage source to the L input on the alternator to see what it takes to turn it on and confirm that it draws 4 amps in that state.

    Best,
    Ken
    Hi Ken,

    That is correct. I connected the brown wire to get rid of the flashing test sequence with the ignition on, but not started. There is more info here: http://dmctalk.org/showthread.php?12181-DMCH-alternator .
    Dana

    1981 DeLorean DMC-12 (5 Speed, Gas Flap, Black Interior, Windshield Antenna, Dark Gray)
    Restored as "mostly correct, but with flaws corrected". Pictures and comments of my restoration are in the albums section on my profile.
    1985 Chevrolet Corvette, Z51, 4+3 manual
    2006 Dodge Magnum R/T (D/D)
    2010 Camaro SS (Transformers Edition)

Page 1 of 4 1 2 3 ... LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •