Results 1 to 12 of 12

Thread: e21 electrical issue after starter motor replacement

  1. #1
    Join Date
    Jan 2017
    Location
    lubbock, texas, usa
    Posts
    6
    My Cars
    1985 bmw e30 325e

    e21 electrical issue after starter motor replacement

    after replacing a bad starter motor on my 83 e21 i ran into some serious electrical issues.

    i got all everything back on except for the brake booster. i hooked my battery up to test the new starter motor but when i touched the the positive terminal to the battery. sparks flew and the grounds near the driver side fender glowed red hot then bursted.

    i got my grounds situated again and rans some tests and found that when the batteries positive lead to the engine is connected, i get the violent reaction for earlier. when i take that lead off the block i get my normal relay clicks and buzzing with normal and strong lights but no crank. i suspect there's no crank because of the new starter motor, i have suspicions that it may bad as well. i tried testing it by crossing the terminals to engage the motor with no results.
    if anyone has any suggestions about the grounding issue im open them because ive exhausted my knowledge on it

  2. #2
    Join Date
    Nov 2007
    Location
    Sacramento, California
    Posts
    4,704
    My Cars
    1980 BMW 320i E21 M10B18

    Cool

    First test I do with a starter replacement is test it off the car with jumpers to the battery, to test its good with an insulated thick screwdriver. Battery Positive Red Cables goes to the start solenoid and fuse box(smaller red wire), and the Alternator B + Positive terminal is connected to the start solenoid via a smaller red wire. Battery Positive terminal does not ever connect to the engine,,the engine is ground and is connected only to negative sources--battery negative terminal , alternator-it casing and the chassis to engine ground, the negative battery post has one more connection to the battery box.

    Randy
    Last edited by 320iAman; 11-17-2017 at 01:25 AM.

  3. #3
    Join Date
    Jan 2017
    Location
    lubbock, texas, usa
    Posts
    6
    My Cars
    1985 bmw e30 325e
    hey thanks for that ill test it. if you have any pictures of how your grounds and leads look id appreciate it if could see them because it sounds like i've got it right but maybe if i had something to compare it to i might find figure something out.

  4. #4
    Join Date
    Nov 2007
    Location
    Sacramento, California
    Posts
    4,704
    My Cars
    1980 BMW 320i E21 M10B18

    Cool

    With sparks jumping there is a negative wire connected to a positive source or a positive wire connected to a negative source--a short. Someone here may have a wiring diagram that you can download.

    Randy

  5. #5
    Join Date
    Feb 2009
    Location
    District Nine
    Posts
    17,984
    My Cars
    sold 78 BMW 320i
    Here's a copy of the wire diagram for 1981-1983
    http://www.findmymerchant.com/images..._1981-1983.pdf

    Be sure to save a copy.
    Tbd

  6. #6
    Join Date
    Nov 2007
    Location
    Sacramento, California
    Posts
    4,704
    My Cars
    1980 BMW 320i E21 M10B18

    Cool

    You dont need to take out the brake booster to change the starter, remove the support bar to the throttle body and remove the rubber hood that connects the volume air box to the throttle body, the starter motor and solenoid then slides in and out with enough room.

    Randy
    Last edited by 320iAman; 11-17-2017 at 11:09 PM.

  7. #7
    Join Date
    Sep 2005
    Location
    monterey, ca.
    Posts
    14,486
    My Cars
    e21, e30 m3. e46 330ci
    you have your battery connections reversed or maybe the positive cable connected to the starter is not isolated and is shorting on the starter housing.
    Tom D

    77 e21 - m42
    88 e30m3
    04 330 dinan3
    84 r1000rt
    02 r1150rs
    all of them gray
    14 f800gsa - red headed stepchild!

  8. #8
    Join Date
    Apr 2014
    Location
    DFW TX USA
    Posts
    1,447
    My Cars
    1983 320I, 1986 325E
    Use this electrical troubleshooting manual to diagnose your problem. The original link was dead so I had to use archive.org to find it. https://web.archive.org/web/20161231..._1981-1983.pdf

  9. #9
    Join Date
    Jan 2017
    Location
    lubbock, texas, usa
    Posts
    6
    My Cars
    1985 bmw e30 325e
    thank you all for replying, i did find the issue it was a simple error, i had put the positive battery lead that goes to the starter on a ground. i don't know how i got them mixed up but it was an easy fix. now i'm encountering a new problem. it turned over, started, then died. now it only cranks. i believe there's no spark. any new suggestions?

  10. #10
    Join Date
    Apr 2014
    Location
    DFW TX USA
    Posts
    1,447
    My Cars
    1983 320I, 1986 325E
    Quote Originally Posted by jerryoung View Post
    thank you all for replying, i did find the issue it was a simple error, i had put the positive battery lead that goes to the starter on a ground. i don't know how i got them mixed up but it was an easy fix. now i'm encountering a new problem. it turned over, started, then died. now it only cranks. i believe there's no spark. any new suggestions?
    Wiggle the green wire coming off the distributor. Also reseat the plug that goes to the electronic ignition module.

  11. #11
    Join Date
    Jan 2015
    Location
    Maryland
    Posts
    17
    My Cars
    1979 BMW 320i Project
    Quote Originally Posted by epmedia View Post
    Here's a copy of the wire diagram for 1981-1983
    http://www.findmymerchant.com/images..._1981-1983.pdf

    Be sure to save a copy.
    Do you happen to have one for a '79?

  12. #12
    Join Date
    Feb 2009
    Location
    District Nine
    Posts
    17,984
    My Cars
    sold 78 BMW 320i
    Quote Originally Posted by NoNothing View Post
    Do you happen to have one for a '79?
    Sure do! Compliments to the originators.
    http://www.findmymerchant.com/images...l/ETM_1979.pdf
    Tbd

Similar Threads

  1. Electrical issue (after replacing ballast)- Door lights not working Halo's etc.
    By wadesconner in forum 2006 - 2012 (E90, E91, E92, E93)
    Replies: 2
    Last Post: 01-11-2018, 08:29 AM
  2. Blower motor issues after Resistor Pack replaced...
    By cstang68 in forum 1992 - 1999 M3 (E36)
    Replies: 11
    Last Post: 09-22-2009, 09:54 PM
  3. serious issue after starter replacement
    By Green95Bimmer in forum 1991 - 1999 (E36)
    Replies: 4
    Last Post: 12-16-2007, 12:42 AM
  4. Need Help ASAP, car wont start after blower motor replacement
    By ledzep244 in forum 1983 - 1991 (E30)
    Replies: 2
    Last Post: 06-26-2007, 08:01 PM
  5. Electrical Issues after Ellipsoid Install
    By toddman35 in forum 1991 - 1999 (E36)
    Replies: 24
    Last Post: 12-24-2003, 12:55 PM

Bookmarks

Posting Permissions

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