ELD issues after swap

Discussion in '6th Generation Honda Civic (1996-2000)' started by MotorMo, Jul 25, 2017.



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  1. MotorMo

    MotorMo Respected

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    Thank you- This test was done at the alternator 4 pin connector, with the ECU connector A plugged in. Sorry for the miscommunication.
    Previous tests I have been testing the ALT C circuit, as pin # 19 (wht/grn) is the alt control wire.
    Previously testing last night showed KOEO , ALT 4 pin connector unplugged at the alternator and testing pin #19 at ECU connector "A" showed no continuity, aka "Open Loop".
    Which was different than 8,000 ohms when the 4 pin connector is plugged in.

     
  2. boofoo

    boofoo Respected Registered VIP

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    The Ohm test I’m interested in should be done at the alternator terminal that mates with 4P connector pin AltC. Ohm test that terminal with the latter connector unplugged.
     
  3. MotorMo

    MotorMo Respected

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    So to confirm, you want me to unplug the alternator connector (4 pin), and measure resistance at the alt control pin at the alternator,(not the wiring harness), to ground, yes? Thanks
     
  4. boofoo

    boofoo Respected Registered VIP

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    Correct!
     
  5. MotorMo

    MotorMo Respected

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    OK- That test yielded 9,100 ohms from the back of the alternator housing to the battery ground. That is with the 4 pin alt connector unplugged and testing the pin where the wht/grn wire goes if the alternator connector was plugged in.
     
  6. MotorMo

    MotorMo Respected

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    Something changed because it looks like I lost 1000 ohms somewhere-- the last test should have shown less resistance not more---But anyways, I cut a alternator connector to use it as a piggy back tester- I tested all pins at alternator with this method- here are the results if it helps at all-
    wht/grn= 9100 ohm to ground
    wht/red= Open loop ( no continuity) to ground
    blk/yel=2500 ohms to ground
    wht/blu= 3500 ohms to ground
    Side note--- I just got finished making a new wiring harness from another 97 Civic EX in case something was goofy in my exsisting harness- but there was no change.
    Here is the existing thread on another sight if that helps as well. The wiring harness (2nd one) is on the last page.
    https://www.ek9.org/index.php?threads/motormos-whip.72379/
    Hope its ok to post that link in this site, if not I'm sure someone will let me know.
     
  7. boofoo

    boofoo Respected Registered VIP

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    Let me check whether resistance to body ground on ECU pin A19 of my 97 Civic is also ~9K Ohms. My charging system is working perfectly.
     
  8. boofoo

    boofoo Respected Registered VIP

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    For my EJ6 with no charging problems, ECU pin A19 reads OL to body ground.
     
  9. civteck

    civteck Respected

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    Just out of curiosity check the harness ground at the t-stat is clean then entice me and put a jumper lead from neg side batt to t-stat ground and retest.. i added a direct 8ga ground from batt to t-stat housing and tuner was impressed, i also have a braided ground from frame to trans no pic but did the same thing on my SS and made a diff. Boofoo narrowed it down im just trying to steal his thunder.. ;)

    Sent from my boujea ass phone
    [​IMG]
     
  10. MotorMo

    MotorMo Respected

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    Thank civteck- I does feel like bad grounds, it is that kind of symptom. The G101 is super clean and tight, but extra grounds aren't a bad idea.
    I did the same resistance test on a 97 Civic EX (the alternator is still bolted up, so I back probed the altC pin on the back of it, and measured resistance to "engine ground")--- My results were ~12K ohms.
    Mixed results. I get it that we are testing the internal circuit of the alternator- I recently replaced the alternator with the same results. Bench testing another Integra alternator I found it also has around 9K ohms with the same test....
    Heres something else -- it does feel like a bad ground- the check engine light it on, due to me not yet hooking up the secondary O2 sensor, anyways, it flickers when I turn on electrical loads- blinkers make it flicker at the rhythm, and so on.
    Thanks for every ones time and input. I put a lot of effort in this car and its kicking my ass.
     
  11. boofoo

    boofoo Respected Registered VIP

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    pic_63.jpg
    Okay. OL to 9K Ohms seems to be within spec for the alternator Altc pin.

    Even when you disconnect the Grn/Red wire (ELD pin 3 to ECU pin D16)?

    Are you able to post the ground and voltage readings for the service manual P1297 and P1298 tests?

    pic_63.jpg

    Expected voltage readings at ECU pin A19 under different conditions:
    pic_59.jpg

    Expected voltage readings at ECU pin D16 under different conditions:
    pic_60.jpg

    pic_61.jpg


    pic_62.jpg
     
    Last edited: Feb 2, 2018
  12. boofoo

    boofoo Respected Registered VIP

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    Can you also say more about this:

     
  13. MotorMo

    MotorMo Respected

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    I will perform theses, and report back my findings during/ after work today. Thank you so much.
    I swapped the ELD from a 99 Integra GSR, because I thought my ELD may be the issue. The Civic VS Integra ELD's are wired different, But all that was needed was to swap two wires in the correct location. I didn't realize that wires are in different location on the ELD 3 wire connector at first- so the symptom my have be masked (less noticeable) by the car running full charge all the time (14.4 volts) as I later realized I had a code for the ELD, which brought me to finding the wiring schematics were different.
    With the Grn/Red wire (ELD) disconnected the headlamps and all burn bright as they should, so I drove it this way for the last half of last year. I don't recall the Check engine light flickering as much, if at all, but it was also stuck at 14.4 volts all day.
    I recently installed an Optima battery so I knew I had a good compositor (battery).

    I added a ground wire from G101 to battery ground this morning- I also will use my DVOM to monitor voltage as I drive to work today and will report back. Thank you for being in the trenches with me!
     
  14. boofoo

    boofoo Respected Registered VIP

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    Is the 99 Integra OBD2B?

    Can you post the differences? I did not see any schematic differences for the 98 OBD2A Integra, though I could have missed something.

    From 98 Integra service manual:

    pic_57.jpg pic_64.jpg pic_65.jpg

    ^This observation seems inconsistent with an engine ground issue.






    .
     
    Last edited: Feb 3, 2018
  15. MotorMo

    MotorMo Respected

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    Humm- I just re-looked up the schematics, and the wiring does look the same between OBD2A, and OBD2B..., so I will look up some paperwork when I get home. Either way, I put the wires back into their factory location after swapping back the original Civic ELD unit, cause the symptom ended up being the same. Never had any codes for the ELD afterwards- Until I unplugged it last year for the races.

    The extra ground wire that I hooked up to ground # 101 to battery ground changed nothing.

    So here is a brain twister- driving to work (10 miles) I monitored the battery voltage through the under dash fuse panel ( driver side )- it never got below 12.7 volts, no matter what. I found that during the 'low charge' times is when the lights got dim (12.7 volts). When it went full charge (14.4 volts) everything stayed bright, and even with every load on, it performed very well.
    Another brain twister- I work at a independent Honda repair shop- a 99 CRV came in today, check engine light on, and I noticed that the check engine light also flickered at the rhythm of the blinker when turned on.......Again later today, I worked on a 97 Accord, with the check engine light on, and it did the exact same thing.
    Now I'm wondering how 'normal' is this--- or how common of a problem this is and no one has talked up much about it.
    It looks like I wont have time today to preform the diag trees for the ELD codes you have presented until later due to a lack of time.
     
  16. MotorMo

    MotorMo Respected

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    Alright- so I have no idea where I got this miss information on the location of the wires in the ELD connector being different from Integra to Civic. So, moving on from that, Further testing has shown that my ELD appears to be working as designed at this time. I guess the reality is when you do an engine swap, and the focus is power not fuel economy. Honda's ELD system was mainly designated for fuel economy. Most stock 'eco boxes' are fine with these parameters. But I wasn't ok with how it affected my ride. So I felt the need to do something,.
    Over recent weeks I've read about so many complaints about the ELD system- flickering of lights, not to mention the nightmares of after market stereos being installed- I decided to take the ELD out of the picture entirely. I played with this idea on my 97 Civic that is stock- I did before and after testing and found by cutting the ELD input wire to the ECU stopped the ELD function This allowed the car to charge like any other car on the road. The alternator still was in control with the internal voltage regulator, running 20%-60% . No check engine light either which is nice, altho there is a code stored. Further studies showed me that Canadian Honda's dont even have that system installed. They're alternator connector is a 3 wire, not a 4 wire. And the wiring schematics from Honda prove this as well.
    Soooo...snip! The car now runs like a champ, no voltage drop, no charging issues at all. Thank you to all who helped me on this path of education.
     
  17. boofoo

    boofoo Respected Registered VIP

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    The old AltC wire snip...

    I'd be curious to know what the difference is in gas mileage with versus without the snip.
     
  18. MotorMo

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    lol- yup, the old snip trick. I actually cut the ELD signal, not the altc wire to ensure the ECU didn't attempt to control anything ELD related.
    Curious also as to how much gas mileage the ELD actually effects. I will never know- this car spends much of its life between 50-100% throttle lol.
    Thanks for all of your time and help boofoo.:thumbs up
     
  19. boofoo

    boofoo Respected Registered VIP

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    The circuit logic looks like this:

    ELD --> ECU --> alternator

    The first and second arrow represent the Grn/Red wire or Wht/Grn wire (AltC), respectively.

    My understanding is that the ELD reports electrical load to the ECU by altering the reference 5 volts supplied by the ECU. In turn, the ECU uses the ELD "load" signal to control alternator output by grounding battery voltage provided by the alternator voltage regulator.

    Theoretically, cutting either wire would completely disable alternator control by the ELD/ECU.

    Given that Canada (CDM) Civics in essence lack both wires, I wonder whether cutting both wires would additionally prevent code 20 from being thrown. Alternatively, the CDM ECU may differ from the USDM ECU, and this is what prevents the CDM ECU from throwing code 20 in the absence of ELD/AltC circuitry.
     
    Last edited: Feb 13, 2018
  20. MotorMo

    MotorMo Respected

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    It is my understanding through internet research, that the ECU is different- different part number even. I have heard of people swapping out their USDM ECU for the CDM ECU and everything works normally- no codes were thrown- as if the CDM ECU doesn't look for the input. That being said, I also wondered if cutting the altc wire would prevent the code but have the same effect.... But I wanted to eliminate any possibility that the ECU could some how off set parameters, thinking that it still had control, and things weren't as they were. So the Grn/Red wire it was lol.
    Side note: Hondata can use the ELD circuit to allow for a wideband O2 sensor hook up. It takes cutting a resistor out, but it allows it to read through a 0-5 volt reference. I guess that's how 'unimportant' the ELD is haha.
     


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