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Thread: 86 Logic Module Interchange

  1. #1
    Garrett booster
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    86 Logic Module Interchange

    In looking for a used replacement LM, I keep seeing different part numbers for 1986 LM's. I'm confused as to what will interchange with what. My factory unit is 5227253.

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    Supporting Member II Turbo Mopar Contributor 85lebaront2's Avatar
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    Re: 86 Logic Module Interchange

    Differences primarily would be auto vs manual transaxle, turbo vs TBI, then it gets into the calibrations for emission certification. I should still have a 1986 Turbo LM from a Chrysler Laser (same as Daytona).
    "growing old is inevitable, growing up is optional"
    1986 Lebaron convertible to replace totalled 85
    1986 Ford F350 Crew Cab DRW
    1995 Lincoln Continental (project car)
    2011 Ford Flex Limited (wife's)

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    Re: 86 Logic Module Interchange

    My NYr is an auto, turbo car. I have checked for continuity from the LM plug to the PM plug anti-dwell wire and it's ok. I have tried 2 different PMs with no change and that's why I'm leaning towards the LM. I'm thinking that it's causing the ASD to shut down my spark. Really don't have the cash right now for a reman unit. Shortly before the car started shutting itself down, it started getting crappy gas mileage. Not sure if one has to do with the other or not.

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    Supporting Member II Turbo Mopar Contributor ajakeski's Avatar
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    Re: 86 Logic Module Interchange

    86 will only work for 86. 85 and 87 will not.
    Turbo logic modules have red and blue wire harness connectors. The biggest difference between auto and manual is idle speed. Auto has a lower idle speed.
    Here's a list of turbo computers:

    http://www.turbo-mopar.com/forums/kn...cu_listing.pdf

  5. #5
    Supporting Member II Turbo Mopar Contributor jeff1234's Avatar
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    Re: 86 Logic Module Interchange

    aj, Can a 1985 T-1 LM be socketed and and serve the same function as an 87 T-2 LM
    The only substitute for cubic inches is cubic dollars, how fast can you afford to go?

  6. #6
    Supporting Member II Turbo Mopar Contributor 85lebaront2's Avatar
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    Re: 86 Logic Module Interchange

    Quote Originally Posted by elmor353 View Post
    My NYr is an auto, turbo car. I have checked for continuity from the LM plug to the PM plug anti-dwell wire and it's ok. I have tried 2 different PMs with no change and that's why I'm leaning towards the LM. I'm thinking that it's causing the ASD to shut down my spark. Really don't have the cash right now for a reman unit. Shortly before the car started shutting itself down, it started getting crappy gas mileage. Not sure if one has to do with the other or not.
    Ok, I repeat what I said earlier, I have a 1986 Laser T1 automatic, it may not be exact for yours (possibly different emission calibration). PN is 5227337.
    "growing old is inevitable, growing up is optional"
    1986 Lebaron convertible to replace totalled 85
    1986 Ford F350 Crew Cab DRW
    1995 Lincoln Continental (project car)
    2011 Ford Flex Limited (wife's)

  7. #7
    Supporting Member II Turbo Mopar Contributor
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    Re: 86 Logic Module Interchange

    Quote Originally Posted by jeff1234 View Post
    aj, Can a 1985 T-1 LM be socketed and and serve the same function as an 87 T-2 LM
    There's some pretty significant trace routing differences in the corner of the PCB where the EPROM chips sit. The '87 TII uses one 128k EPROM and a timer IC instead of 2 64k EPROMs. I started to design a daughter board to convert the former to the later, but without a source for the timer IC it's completely pointless.

  8. #8
    Supporting Member II Turbo Mopar Contributor
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    Re: 86 Logic Module Interchange

    Highly unlikely as a t-2 requires a stepper motor control for the AIS, this stepper motor is used on T2 and 88+ T1. the T-1 87 and older uses a regular DC motor on a log intake.
    The stepper motor AIS requires an H bridge driver that is only on T-2 ready LM ECU. It has been noted that some later 86+ T-1 LM has the necessary H bridge drivers. As a note my 87 T-1 Sundance (manufactured July 87) does have the T-2 ready LM.
    The EPROM chips are also very different 27c64 vs 27C128.
    Also the distributor of the 85 is very different, IIRC.
    Last edited by chromguy; 03-27-2020 at 04:22 PM.
    Regards,
    Miles

    DD '87 Sundance T1, 12PSI, SLH with rear disks
    '87 CSX #432

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    Supporting Member II Turbo Mopar Contributor jeff1234's Avatar
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    Re: 86 Logic Module Interchange

    Thanks Miles and Turbo SOB, I would be interested in an 87 T2 lm if someone has a good spare.
    Jeff
    The only substitute for cubic inches is cubic dollars, how fast can you afford to go?

  10. #10
    Supporting Member II Turbo Mopar Contributor jeff1234's Avatar
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    Re: 86 Logic Module Interchange

    Miles, my LM must have been made recently enough and it does run the ais motor. My intake is from an 89 as is the ais.
    The only substitute for cubic inches is cubic dollars, how fast can you afford to go?

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    Re: 86 Logic Module Interchange

    Quote Originally Posted by jeff1234 View Post
    Thanks Miles and Turbo SOB, I would be interested in an 87 T2 lm if someone has a good spare.
    Jeff
    I will ask around
    Regards,
    Miles

    DD '87 Sundance T1, 12PSI, SLH with rear disks
    '87 CSX #432

  12. #12
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    Re: 86 Logic Module Interchange

    Quote Originally Posted by 85lebaront2 View Post
    Ok, I repeat what I said earlier, I have a 1986 Laser T1 automatic, it may not be exact for yours (possibly different emission calibration). PN is 5227337.

    I would be interested in it. Wish I still lived in Chesapeake, it would make getting it easier. What would you have to get for it? I think it should be able to be shipped for about $10. Let me know. Thanks.

  13. #13
    Supporting Member II Turbo Mopar Contributor 85lebaront2's Avatar
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    Re: 86 Logic Module Interchange

    Let me check on what it will fit in, I think a small flat rate box should work. As for the LM, figure $50, I have no use for it as I am now using an SBEC.
    "growing old is inevitable, growing up is optional"
    1986 Lebaron convertible to replace totalled 85
    1986 Ford F350 Crew Cab DRW
    1995 Lincoln Continental (project car)
    2011 Ford Flex Limited (wife's)

  14. #14
    Rhymes with tortoise. Turbo Mopar Staff cordes's Avatar
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    Re: 86 Logic Module Interchange

    In my experience, any 87 LM will run 87 TII systems.

  15. #15

    Re: 86 Logic Module Interchange

    Thanks Miles and Turbo SOB, I would be interested in an 87 T2 lm if someone has a good spare.
    Jeff

    ^^ There are multiple ways but this is the best way and def. get it socketed.

  16. #16
    Supporting Member II Turbo Mopar Contributor ajakeski's Avatar
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    Re: 86 Logic Module Interchange

    Quote Originally Posted by jeff1234 View Post
    aj, Can a 1985 T-1 LM be socketed and and serve the same function as an 87 T-2 LM
    Nope. Each year LM will only work with that years calibration file. 87 will work with turbo I and turbo II cals.

  17. #17
    Supporting Member Turbo Mopar Contributor GLHS60's Avatar
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    Re: 86 Logic Module Interchange

    Don't forget the 1 exception, 1987 Shelby Charger is actually still a 1986 LM.


    Thanks
    Randy


    There is no logical reason to call an Engine a motor.

    Randy Hicks
    86 GLHS60
    86 GLHS 373 : SOLD, but never forgotten
    89 Turbo Minivan
    83 Turbo Rampage : SOLD
    Edmonton,Alberta,Canada

  18. #18
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    Re: 86 Logic Module Interchange

    Quote Originally Posted by cordes View Post
    In my experience, any 87 LM will run 87 TII systems.
    Same here.

  19. #19
    Rhymes with tortoise. Turbo Mopar Staff cordes's Avatar
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    Re: 86 Logic Module Interchange

    Quote Originally Posted by GLHS60 View Post
    Don't forget the 1 exception, 1987 Shelby Charger is actually still a 1986 LM.


    Thanks
    Randy
    Great catch. Thank for pointing it out Randy.

  20. #20
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    Re: 86 Logic Module Interchange

    Great! Thank you 85lebaront2. I have seen LMs on Ebay, but I have been leery of buying one. There are some sketchy people selling there. I much prefer buying from a fellow turbo Mopar enthusiast.

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