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Resolved Alternator not charging battery.

Posted by jakk220, May 21, 2017

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  1. jakk220

    jakk220 Proven Member

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    Long story as short as possible, my battery was dead everytime I shut the car off and it needed jumped. After I jumped it, it ran fine off the alternator. Ok... Dead battery. Replaced the battery, drove it a while, and got on into boost for the first time since my new transmission and the car was braking up at full boost.

    Again, found out alternator was still not charging. At no time have I had a battery light yet. It puts out about 12v, enough to keep the car running apparently. So I replaced the alternator and had the new one tested before I put it on. Tested fine. I got the battery fully charged and put the new alternator on and still, 12v.

    So I checked the wiring for the "charging relay diode fuse thing" and the blue wire was broke. Fixed that and made sure the bulb in the cluster was good, and still nothing changed. If I touched the blue wire to I believe the black and yellow wire it worked when the key was on Acc, but still only 12v.

    Alternator fuse is good, I checked it. No other wires appear broken. I did disconnect the alternator harness from the alternator and it went up to about 14.3v at idle.

    Im lost. Does anyone know what I should check next?

    I was also wondering if someone could please post a picture of the harness for the alternator relay and where the wires go to it. I used spade connectors in place of the old broken harness but want to make sure they are all there and in the correct place. To my knowledge the car shoyld still charge with this desconected anyway though.
     

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  2. SexyDSM95

    SexyDSM95 Proven Member

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    I am doing a wire tuck right now. What pics do you need exactly? The alternator harness goes to the fusebox and that diode or the "generator relay" that Mitsu calls it hangs around the fusebox. Then, you have those 4-white wires that go into the fusebox between the 100A fuse and the fusible link.
     
  3. jakk220

    jakk220 Proven Member

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    I just need the one for the "generator relay" plug. Even though I don't think you have to have it hooked up for the alternator to work, I'm replacing it because I have no other idea what could be wrong. If I leave the generator relay unplugged, the battery light does not work at all. If I bridge the wires it will only come on with the car off and key forward. I did notice however that the battery light is slightly more dim than the rest of them.

    A picture of the back of the plug and what wires go where would be much appreciated.

    The last idea I have is to replace the alternator again even though it tested good. I do recall one time when I replaced the alternator and the old one tested good when it indeed was bad. The odds of that happening twice I feel are slim, but its a last option LOL.
     

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  4. SexyDSM95

    SexyDSM95 Proven Member

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    Alternator Plug:
    B02DDB3A-5F7F-49B2-A9EC-15F08EE958E4_zps3irf6zic.jpg
    Wires:
    White - leads to harness plug
    Red - leads to fusebox (40A Headlamp)
    Black with Yellow - leads to the "generator relay"
    Green - leads to harness plug

    Generator Relay/Diode Thing:
    B48CDC46-6055-400D-9F58-B797D3398FAC_zpssbnlq5u5.jpg
    Black with White - leads to interior fusebox harness
    Blue - leads to interior fusebox harness
    Black with Yellow - from the alternator harness

    Interior Harness Fusebox & ECU (driver's side)
    BDDBB133-09A4-4A25-8672-70AB9F16DE2D_zpsootauxha.jpg
    Here is where most of the other wires lead to.

    Then you have the 2 white wires that go to the fusebox 100A fusible link.

    Here is a description I found about the relay. IIRC, the alternator won't put out if voltage isn't on one of the pins.
    Source: http://www.dsmtuners.com/threads/wh...ng-system-relay-on-a-2g.248161/#post151081889

    Good luck!
     
    Last edited: May 21, 2017
  5. SexyDSM95

    SexyDSM95 Proven Member

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    Here is the official circuit diagram from my Mitsu Service Manual to give you the proper connector names. Let me know if a section is blurry and I can grab a closer pic.
    0AFC9ECE-857F-4D87-8D47-5D0618FF4BE7_zpsnvrdaulv.jpg
     
  6. jakk220

    jakk220 Proven Member

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    Awesome thank you! So I definitely have it wired wrong right now. I just assumed that the blue wire went to the other prong coming off of the relay, when it appears that it is tied in with the black and yellow and that prong is just left empty. So maybe that is my issue? I am not the best with wiring and diagrams. I guess I will just try to put the new relay on and make sure that it is wired correctly and see what happens.

    I wonder if the relay can just be bypassed as long as the light is working.
     

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  7. SexyDSM95

    SexyDSM95 Proven Member

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    Black and yellow goes from the alternator plug to that generator relay.

    Blue wire goes from generator relay to that interior harness (C25) which goes to the instrument panel wiring (My 3rd pic the plug on the left) which looks to be for the instrument cluster for the "charging warning light".
     
  8. jakk220

    jakk220 Proven Member

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    Gotcha. I am hoping once I correct my wiring it will fix it. Is there any other fuses that I should look at to make sure that they are not blown? I checked the one under the hood for the alternator, but I wasn't sure if there was any more that I should check.
     

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  9. jakk220

    jakk220 Proven Member

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    Replaced the generator relay and corrected the wiring. The battery light works now, but doesnt come on when driving. Yet the battery still isn't getting a charge. Alternator fuse was double checked, battery tested again....what am I missing here?
     

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  10. jakk220

    jakk220 Proven Member

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    Again, the battery will get a charge if I unplug the alternator, so that would make me think the wiring is good. Should I replace the alternator again?
     

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  11. jakk220

    jakk220 Proven Member

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    Anyone have any suggestions if this new alternator I put on Thursday doesn't fix the issue? I figured the ECU is a possibility but would like to know how to test it. I'm basically a potato when it comes to a multimeter so if anyone could give me a step by step that would be awesome. If the ECU was bad I would think I would get a battery light or a p1500 code but I'm not...
     

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  12. Vegas smith

    Vegas smith Proven Member

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    Could you describe your alternator setup? Is it stock, Saturn, relocated etc? Sorry, I don't remember if you mentioned it and you have no pics in your profile.
     

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  13. jakk220

    jakk220 Proven Member

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    Sorry, It's stock. All of the wiring is factory as well. I have never done a wire tuck or anything.
     

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  14. jakk220

    jakk220 Proven Member

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    Update: I replaced the alternator again (this new one and old one tested 14.6v at autozone) and no change in the voltage. Still sits at 12.6-12.8. Here is a list of my information I know in one post. I really am in need of a hand with this one.

    1. Alternator and battery are new and have been tested multiple times. Both are good.
    2. Voltage is 12.8 and doesn't change with reving or headlights.
    3. Relay has been replaced and tested. It is functional
    4. Battery light is tested and works with key on. Goes off and stays off after engine is started.
    5. Voltage drops to 11.6 with 4 pin alternator harness unplugged.
    6. 4 pin alternator plug puts out 4.9v on the FR terminal and 0 at the G terminal with key on. From what I have read this should mean the ECU is okay?
    7. I ran a wire straight from the alternator post to the battery, no change in voltage. Alternator also only puts out 12.8 volts at the post.
    8. Fuse tested and is functional
    9. Alternator belt tension is correct and belt is in good condition.
    10. Car will run with the battery unplugged. Its just not charging the battery as it should due to low voltage.

    I am stuck. I have tested everything. Its like once the alternator goes on my car, it puts out ow voltage, but at autozone it does fine at 14.6. The only other thing that I can think of is that the alternator is not grounding properly. How would I test that? Could I just hook a jumper cable to the casing and ground it to the battery and see if that helps? I need suggestions badly. I'm out of ideas.
     

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  15. 91talonts1

    91talonts1 Proven Member

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    Just an idea here but, the white wire on the alternator plug is the "generator g pin" it goes to pin 33 on the ECU. When the ECU grounds it, the alternator enters a low voltage mode and outputs below 13v, when it's left floating the alternator is at max output. http://www.ecmtuning.com/wiki/ecualternatorcontrol?s[]=2g&s[]=alternator
    Maybe either your ECU is constantly grounding it or the wire is physically grounded somewhere. Try disconnecting just that wire and see if it doesn't start outputting full voltage. I have the g terminal disconnected permanently in my car to disable the ecu's control over the alternator.
     

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  16. jakk220

    jakk220 Proven Member

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    What would be the easiest way do disconnect just the G terminal without having to cut the wire on the harness?
     

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  17. tay97gst

    tay97gst Proven Member

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    It could be your ecu. On the 2g the alternator output is controlled by the ecu, so if part of that system blows or goes bad it can ground pin 33 and keep the alternator in low output mode. When you unplug the alternator harness you remove the connection running to the ecu and thats why you can get a full output with the harness disconnected. I had the same issue and i sent my ecu to ecmtuning and they confirmed the transistor was blown and they fixed it for a great price.
     

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  18. jakk220

    jakk220 Proven Member

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    I'm thinking I'm going to have to send my ECU out... Is there any way to test that to confirm the ECU is at fault?
     

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  19. 91talonts1

    91talonts1 Proven Member

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    I just depinned the white wire from the alternator connector, and tucked it back up in the harness.

    Easiest way to test this I'm thinking would be checking for continuity to ground on just the wire, and then if that checks out then with the ECU on.
     

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  20. jakk220

    jakk220 Proven Member

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    Thanks. Ill give that a shot and report back. Hopefully the ECU is the culprit.
     

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  21. Vegas smith

    Vegas smith Proven Member

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    Send it to ecmlink. They are super fast.
     

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  22. jakk220

    jakk220 Proven Member

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    I would definitely send it to ECMlink. I love their customer service and how they keep you updated on every step of the process. I think i'm going to depin the G terminal and try it on Tuesday. Regardless if that works or doesn't work I think I'm going to send the ECU out anyway to rule out the possibility.
     

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  23. jakk220

    jakk220 Proven Member

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    Might be a stupid question... But how do you depin the alternator wiring harness? I can't seem to figure it out.
     

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  24. 91talonts1

    91talonts1 Proven Member

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    Just like any other connector, there's a little plastic tab holding the pin in the body of the connector. Stick a tiny flat head or something in there to push it out of the way, the pin will then slide out the back.
     

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  25. jakk220

    jakk220 Proven Member

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    Forgive me, I have never depinned any connector LOL. I'm not much for wire tucks. Do you just put the screwdriver where the metal connection is, or the hole below it? And do you just push in on it or do you have to pry on it?
     

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