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Thread: Early E23 L-Jet Ballast Resistor Glows Red Hot

  1. #1
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    Early E23 L-Jet Ballast Resistor Glows Red Hot

    Hi, new member here but I've had my '81 E23 for about a year. Slowly been sorting stuff out.

    When I first got it, one of the issues I came across was a bad ballast resistor. It's the three prong one for pointless systems. When I hooked up the replacement one, the wire that runs from the resistor to the starter made the resistor glow red almost immediately and it made run poorly. I've had that wire Disconnected for awhile and it seems to be running fine.

    I seem to understand that the ignition system uses this wire to get a full 12 volts at startup and then decreases the voltage to preserve the coil. Is this correct? I'm wondering if the wire is connected at the correct terminal coming from the starter?...it's black/red and was positioned at the 12o'clock position on the starter solenoid. The only other terminal is at the 6o'clock position and is for the neutral safety switch. Is it possible that they are switched?

    I've checked the resistance of the resistor itself and it showed exactly what's listed on the resistor for each terminal end---0.4 and 0.6

    Any other ideas? Thank you all in advance.
    Last edited by cargeek733; 02-27-2019 at 04:44 PM.

  2. #2
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    Instant hot implies current is passing to ground or shorting out. I would check for continuity to ground at each terminal/wire and make sure nothing rings through.


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  3. #3
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    what's the course of action if something does ring through?

  4. #4
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    Follow that wire to a break or crush or wrong connection. I would most suspect the wire that goes to the testing port.


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  5. #5
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    So here are the results: battery connected, ignition off, I had two wires beep.

    First one, using the descriptions from the fiche you provided, was the 1,5 GN that runs to (B) engine plug terminal 15

    Second one was the 1,5 SWRT that runs to a terminal on the starter solenoid.

    Should the starter solenoid be ringing through? I checked the terminal that the red/black wire from the resistor to the starter connects to and it rang.

  6. #6
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    So battery connected, ignition off, here is what I got:

    I had two wires ring through.

    First one, using the fiche that you provided me, is labeled 1,5 GN and runs to (B) Engine plug term 15

    Second one, labeled 1,5 SWRT runs to the top terminal on the starter solenoid.

    Should the terminals on the starter solenoid ring through? I checked both terminals that are on the starter solenoid and they both rang through.

  7. #7
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    Quote Originally Posted by cargeek733 View Post
    So battery connected, ignition off, here is what I got:

    I had two wires ring through.

    First one, using the fiche that you provided me, is labeled 1,5 GN and runs to (B) Engine plug term 15

    Second one, labeled 1,5 SWRT runs to the top terminal on the starter solenoid.

    Should the terminals on the starter solenoid ring through? I checked both terminals that are on the starter solenoid and they both rang through.
    To be sure I’m communicating clearly, when testing for continuity to ground place the positive end of your meter to the disconnected spade end of the ballast wires and the negative end of the meter to a known ground on the engine. If the ground circuit is touching that wire it will ring through and that wire has a short in it somewhere. If this is how you tested the wires and 2 rang through you have something crossed up somewhere.
    You can also follow the diagram to the opposite end of each wire and test from the other end. Red to positive and Black to Chassis ground with your meter again.


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  8. #8
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    Negative end of the meter was on one of the three studs that comes from the shock through the shock tower. I verified that it would actually ring by putting the positive end on an actual ground wire.

    Do I need to touch the negative end on the engine itself?

    The first wire that rang using shock stud was 1,5 GN that runs to engine plug term 15

    The second wire that rang using the shock stud was 1,5 SWRT...when I first tested it, I had it disconnected from the terminal on the starter solenoid and it Did not ring through. When I reconnected that wire to the terminal on the starter solenoid, it rang through.
    Last edited by cargeek733; 03-01-2019 at 12:41 AM.

  9. #9
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    No a good ground is all. Just a sec. I almost have it figured out


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  10. #10
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    I don’t have a wiring diagram for a non-turbo e23. I am sure that the short is not to the starter. The ignition sets the relay to ground with the key off. That is why it rang connected. My turbo diagram shows the test port wire also connects to the TIC R module at terminal 15E this may be a ground while closed also. If you have a wiring diagram specific to your model check to see if the test port circuit is shared with any other control modules. If not your short is in the test port wire. Check continuity from the test port to the ballast connector to find the right pin in the test port then check if it rings through the chassis ground. Sounds like the short is in that line.


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  11. #11
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    Oh, what a mess that is in that picture haha!

    I just checked the wire from resistor to starter...plugged it in to resistor and unplugged from starter, tested for continuity from starter side of wire and got no ring. So seems you're right about ignition setting relay to ground with key off. If I click the ignition on, can I test for continuity from the same wire connected to the starter solenoid and see if it's still grounding?

    Is the TIC R module the same as the ECM? According to my Chilton manual, that green wire runs to the Engine Control Module at terminal 15 and is also connected to the Test Connector. Where is the test connector on our cars?

  12. #12
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    Yes you can check with the ignition on.


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  13. #13
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    TCI R and TCI modules are separate from the ECU. They control turbo fuel enrichment and ignition timing to boost ratio.


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  14. #14
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    Picture above is the harness from my 745i. I removed it and replaced it with a Megasquirt computer and harness


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  15. #15
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    Chilton.jpg

    Here is the diagram from my Chilton manual

  16. #16
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    So ignition on, I got no ring from the green wire to the ECU.

    The black/red wire from resistor to starter solenoid, it was making my meter make a weird sound...not really a ring, but a slight buzzing sound. ohm reading was bouncing around 50, 60, 100, back and forth between those general numbers.

  17. #17
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    Edit, the green wire gives a really really quick chirp with the ignition on and then silence.

    - - - Updated - - -

    I also noticed that with the ignition on, the second terminal on the starter solenoid that was previously grounding was no longer giving me a ring...only the terminal that's wired to the resistor was still giving a ring.

  18. #18
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    The green wire shares a circuit with a charge indicator bulb in the dash. It grounds through the filament.
    How many poles are on your starter? Diagram shows 5 connections plus a ground.


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  19. #19
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    I hate to sound like I’m guessing, but without knowing for sure what the internals of that ballast resistor look like, I would say the black and red wire must connect to switchable ignition power source on the starter. It should connect to a pole that only has power with the ignition on. That should also power the coil on. Otherwise, there would always be +12V at the coil. You wouldn’t be able to turn off the engine. Right now the only way I can find +12V to your coil without the red/black wire connected is returning from the ignition switch back to the ballast resistor through terminal 15 on the ECM.


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  20. #20
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  21. #21
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    Test port looks like this. Driver side Omer fender on mine


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  22. #22
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    starter.jpgimage1 (2).jpg

    This is my starter. You can see the red/black wire from the resistor at the 12 o'clock position on the solenoid.

    Looks like I need to tighten up that hose above the starter lol.

    - - - Updated - - -

    Found the test port...I was blanking for some reason...I knew where it was. It sits immediately behind the thermostat housing on mine.
    Last edited by cargeek733; 03-01-2019 at 02:57 AM.

  23. #23
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    My primary concern would be the melted sheathing on the red wire that shares the loom with the black and red wire. There are three wires connected to the positive post on the starter. A black and two reds. The black is direct to the battery. One red goes to the alternator and the other red to the electronic control relay. The black and red wire that returns to the ballast resistor shares the loom. If that red wire melted through the black and red wires insulation it will ground out the battery as soon as you turn off the key.


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  24. #24
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    The two red wires that share a terminal lug on the starter, they both come out together on the alternator end of the loom.

  25. #25
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    I would disconnect the black and red wire from the starter and from the ballast resistor. This should mean it has no connection in the circuit. Then pick either end of the red wire, the starter end or the ballast end end connect your meter to it. Place the other test end to the positive terminal post on the starter and see if current is passing from the pole into your black and red wire. That will tell you if the wires have melted together in the loom.

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