Starter relay bad?

Discussion in 'Mk5 VW Jetta, Sportwagen, and Audi A3 TDI forum' started by weffy, Oct 22, 2017.

  1. weffy

    weffy New Member

    Joined:
    Jul 4, 2013
    Messages:
    3
    Car:
    Passat 1997
    Last winter the starter in my '05.5 Jetta tdi would sometimes not engage the flywheel. I replaced the battery and the starter, but no improvement. It is starting to do it again - it is engaging still but is noisy, like it is barely engaging. I checked the voltage to the solenoid and it is 5.5. Shouldn't this be 12? I'm no expert, but wouldn't this cause my problems? Could this be a bad relay - J682? I see 2 part #s, 3D0951253A($4.63) by Vemo and 7N0951253($42.08) OEM at ECS tuning. What do you think?
     
    Last edited: Oct 22, 2017
  2. Peca

    Peca Member

    Joined:
    Jun 12, 2013
    Messages:
    118
    Car:
    Passat b6, 2007, 103 KW
    Location:
    Pale, Sarajevo BIH
    It seems that you have a voltage drop somewere between the baterry and starter motor. On the solenoid should be a battery voltage.
     
  3. Ol'Rattler

    Ol'Rattler Well-Known Member

    Joined:
    Apr 24, 2011
    Messages:
    833
    Car:
    06 TDI Jetta
    Location:
    Marysvile, WA.
    Check the big wire that goes to the starter from the battery. You should get battery voltage (12 volts) if you check between the big wire terminal nut on the starter and any ground. 5 volts would indicate that the big wire has loose or corroded connections or the big wire were it goes into a terminal is corroded.

    The description on ETS is wrong. The power supply relay provides battery power to actuate the solenoid (small wire). It does not provide battery power for the starter motor. Battery power for the starter motor is supplied by the big wire.
     
    Last edited: Oct 24, 2017
  4. weffy

    weffy New Member

    Joined:
    Jul 4, 2013
    Messages:
    3
    Car:
    Passat 1997
    The big wire does have 12v. The small wire to the solenoid has 5.5v. I bought a new relay. I don't know the exact location of where it resides. I think it is in the dash in the area below the headlight switch, but i will check the relay/fuse box under the hood first. Hopefully the relay fixes it and it is not a bad wire or corrosion somewhere else. Thanks for the replies.
     
  5. weffy

    weffy New Member

    Joined:
    Jul 4, 2013
    Messages:
    3
    Car:
    Passat 1997
    Time for an update. I found the location of the starter relay - it is in the fuse box under the hood. It is the relay closest to the center of the box. It is labeled 433 and is next to another relay 433. After multiple tests with the 2 existing 433s and my new relay, the results are mixed. Sometimes I got 11.8 to 12 volts with each relay, sometimes I get 5.5 with each relay. The relay doen't appear to be the problem.

    I've cleaned and applied silicone grease to the battery posts, the main chassis ground, the big starter terminal, both ends of the starter negative cable, the 3 other grounds in that area and the power supply to the fuse box. Normally I have 12.4 volts on the battery although sometimes it is only 12.2. I have 14 volts at the battery with the engine running.

    I tested the voltage at the relay sockets and got the same 11.8 to 12.0. Is that a clue that I am not getting battery voltage there? Is there another relay involved in this system? Any suggestions?
     

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