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P1750 TCU possibly?

Posted by 805LegendDSM, May 14, 2014

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  1. 805LegendDSM

    805LegendDSM Proven Member

    84
    1
    Joined Apr 14, 2011
    Oxnard, California
    Well, my DSM I back to acting up again.

    On arriving a red light the car went a head and threw a checking engine light. Then trying to take off the car was so slow, almost like if the transmission was slipping. But realized I was stuck on 3rd gear, and the OD button wasn't working. So I decided to manually shift it to 1st/L and nothing, but 2nd seems to work almost instantly shifting erratically.

    Neutral, Reverse and 2nd work but stuck in 3rd..

    Did my research obviously the car is in Limp mode (experienced this before)

    Ran the codes and P1750 came up (transmission Solenoid assembly?)

    From what I read the car needs new solenoids? So I thought I would test then and see which one is bad, there's supposedly four of them? And was wondering if there's a way to clean the connectors or are they even exposed and not in the tranny?

    Now I read that since it was stuck in third and on limp mode, it automatically means, BAD TCU? If that's true May a 96 auto non turbo TCU be used (dumb question but hey I had to throw it out there) TCUs are expensive online as hard to find period!

    Oh and one last thing....

    This doesn't happen just everytime I turn /drive the car. If the car is driven without letting it warm up completely it seems to happen sometimes.

    So far after leaving it warme up to operational temperatures it doesn't seem to happen , only did once. But yes this is pretty much on and off, bad solenoid? Bad TCU?

    Update: sorry for double posting but, just went outside on my lunch and my car wouldn't start as usually it hesitated like if it had a weak battery, waited a couple seconds, turned it off, and then now it wouldn't start at all?

    Waited a minute and then it started but again hesitated, dash lights dimmed like if the battery was dying?

    Can a malfunctioning alternator cause the ar to go on limp mode?
     
  2. TurkF26

    TurkF26 Supporting VIP

    334
    4
    Joined Sep 6, 2003
    vacaville, California
    Since you are located in California, Craigslist has a lot of TCU's for cheap, as does Pick N Pull. I just went to my local Pick N Pull and they had 3 turbo dsms, 2 auto GST's and 1 manual GST. You can find a TCU pretty cheap.

    TCU Part # is different for the Non turbo to the turbo models so pretty sure they will not interchange.

    TCU Codes

    The above link is an excellent website to go to to see what is really going on with the TCU and tranmission. I would recommend you go the the above site and narrow down exactly what is going on before throwing parts at it.

    Hope this helps
     
  3. 805LegendDSM

    805LegendDSM Proven Member

    84
    1
    Joined Apr 14, 2011
    Oxnard, California
    Once again sorry, but I'am stuck at work, I'm not trying to bump my post but to update that way I don't have to answer on coming questions.

    Went at lunch, now my car wot start, it barely turns over but it's not completely drained, since stereo works and windows go up so the battery ain't dead. Just doesn't have enough juice to start the car.

    I checked battery connections, and felt one (+) of the connections loose, so I decided to tighten it, then noticed it literally broke in half, now idont know if it was already like that or if I accidently broke it.

    May this be the cause of my limp mode?

    Not enough voltage making the transmission go into limp mod? On and off depending on power? Just a thought.

    Again I'm stuck at work at 102 degree weather guys some one please reply seems like everyone just replies on the easy questionable stuff LOL

    Thank you for the link brotha that's what I was lookin for!

    Update:

    Replaced battery connector with new one , let it run for a bit, turned it off, and tried to start it, wouldn't start, had to jump start...

    Got it running right away went on limp mode stuck in 3rd, drove it home 15 minute drive. 5 minutes or more with the car shut off, decided screw it I'll start it up see if it won't start.

    It did....I'm confused guys, car fired up with no problem. Turned it off ...tried again so signs of it hesitating to start, it just fires up fast?

    So I'm guessing my alternator is cool? My battery has a green sticker that says 1/13 is that an expiring date?

    Gonna troubleshoot the TCU codes.
     
  4. TurkF26

    TurkF26 Supporting VIP

    334
    4
    Joined Sep 6, 2003
    vacaville, California
    You can take your car to a local auto parts store (Auto Zone, O'Rielly's, NAPA, etc...) and most will test your alternator / battery to make sure its good. You can also start the car at night and turn the headlamps on, stereo, etc... pretty much put a full drain on the system. If your headlamps dimm a lot, or pulsate, or interior lights seem to flicker, then you probably do have an alternator problem.

    You could also have a ground cable problem. My auto GSX did some weird tranny stuff one time and after spending hours going through everything, my ground cables where worn and frayed. When I replaced them with 4 gauge wiring, car ran great and trans shifted perfectly.

    Also have you replaced the fluid at all? If so what did you use? Mitsubishi ?
     
  5. 805LegendDSM

    805LegendDSM Proven Member

    84
    1
    Joined Apr 14, 2011
    Oxnard, California
    My alternator is fine, I ddnt have it tested at autozone but I did use a multimeter and checked the battery and it's connection, after replacing the batter connector it starts right up.

    I've checked the Trans fluid yesterday it's low , and it's brown, which I'm guessing it's not good at all? Could that be a possibility?
    Also, I tried trouble checking the TCU codes, I followed eactly what the link said , it's hard the OBD2 plug is up site down or something, also I have a digital multimeter it was impossible to find the pulses.

    Also I wanna thank you so much for everything ...

    Update: Maybe the alternator is not fine, this morning for work the car barely started ...

    I'm afraid as soon as I get to work it's not gonna start.

    I'm in the car right now, it's on limp mode, now it's more sluggish than ever it won't even boost...you hear my turbo loud spooling like crazy but I ain't going anywhere.

    Once I get home im going to take the alternator to go get tested and battery to see if it holds charge, one of the two has to be faulty to ause my starting problem, and as for my transmission problem it happens randomly sometimes it's fine, then some times it does it? Shouldn't it be on all the time if a solenoid was the problem?
     
  6. TurkF26

    TurkF26 Supporting VIP

    334
    4
    Joined Sep 6, 2003
    vacaville, California

    How many miles are on your car? Has trans or Torque Converter ever been rebuilt or replaced? Trans fluid should not be brown, it should be a transulcent red color.

    Did you check your ground cables? Your negative battery cable? Are they not frayed and bolted down tight?

    If you are boosting and not going anywhere, that definitely sounds like a tranny / more of a torque converter issue. It could also be that your fluid is really low and you are burning the trans fluid since there is not enough. I would highly recommend you drain and refill the entire A/T system and make sure you use the right fluid. I only buy mine from Mitsubishi personally.
     
  7. 805LegendDSM

    805LegendDSM Proven Member

    84
    1
    Joined Apr 14, 2011
    Oxnard, California
    280,*** miles

    And, I checked my ground connections all seems to be good, everything on tight.

    This just all sarted randomly happening on Tuesday something's not right.

    I bought the car in Jan, since then I've wanting to do a whole rebuild to te motor, never the transmission.

    It's an on and off kinda thing, if it's the torque converter would it go on and off limp mode?

    And the me boosting and not going anywhere is the BoV type s knock off, it's leaking so bad ima throw the stock bov if that changes things. The sluggish just started today and then yesterday I put the TYpE s on because I did the single spring mod again and the car boosted fine till then, even on limp mode I was boosting 12psi pulling hard, except in third gear :D

    Ima go a head and try to change the trans fluid with Mitsubishi fluid hopefully this weekend once I figure out where to pour into and how to drain LOL

    Also tomorrow I'll take out the alternator and battery get them fully tested(my alternator seems to make this weak grinding noise like if these small BBs in a can type of noise)


    I need to just pin point what it is that way, I dot just I buy a torque converter or tranny and then it being the TCU or some bull..

    Question: I hear there's this manual box mod or something that will make you have to shift manually? Can this by pass the limp mod? (It's probably isn't safe)
     
  8. TurkF26

    TurkF26 Supporting VIP

    334
    4
    Joined Sep 6, 2003
    vacaville, California
    low fluid would make it go into limp mode

    Theres a drain and refill plug on the front bottom area of the transmission, remove the airbox and possibly upper intercooler pipe to get easy access to it.

    I have left mine stock and not messed with it. You can buy shift kits, stall converters, etc... that will help. There are quite a few mods and maintance items I would do before tearing into the automatic tranny.
     
  9. 805LegendDSM

    805LegendDSM Proven Member

    84
    1
    Joined Apr 14, 2011
    Oxnard, California
    I did that ghetto test, once I got home.

    While the car is on idling at normal temperatures, the battery read 13.3

    Headlights on an radio and defroster full blast, the volts dropped to 11.2
     
  10. 805LegendDSM

    805LegendDSM Proven Member

    84
    1
    Joined Apr 14, 2011
    Oxnard, California
    RESOLVED:

    before attempting to take the alternator and battery off, While unhooking the ground battery cable. I checked ground, and sure enough on one end, it wasnt bolted on anything. I recognized the cables location before, it's bolted on the tranny with a bolt that holds the starter in. I looked down the bay with a light and sure enough the Bolt was sitting right on top of the tranny LOL..

    The bolt ain't stripped it bolted back in perfectly...grounded..

    The car hasn't acted since ...no dying no limp mode! Thanks !
     
  11. TurkF26

    TurkF26 Supporting VIP

    334
    4
    Joined Sep 6, 2003
    vacaville, California
    Great job! I am glad you found that cable. I also hope it sloves all of your driveability problems. :)
     
  12. 805LegendDSM

    805LegendDSM Proven Member

    84
    1
    Joined Apr 14, 2011
    Oxnard, California
    BUMP: this after exactly a year later, it happened again , except this time it's not going away. Once the car starts and warmed up to its normal temperature, it drives fine , then shifts erratically and goes into limp mode once the check engine light is on, that's when I know I'm stuck in 3rd gear, now when it happened earlier this month I checked the code and it read P1750, i don't know how I ended up thinking it was my Neutral Shift Switch from doing so much research. But once I checked and located the switch it was loose, being held down by a 10mm bolt I found it loose. I then figured out I wasn't suppose to be like that so I though maybe that would solve my problems. Wrong after messing with it the car would sometimes run great for a day or two then it would happened, then I figured how to align it the proper way and the problem still exist. After aligning it do I have to disconnect the battery and 30 minutes to reset the ECU & TCU?

    Anyways went back to doing more research and came up with people just buying the 4 solenoid pack from IPT for 220 and it solved their problems. Now right I'm still yet to test all the solenoids but I'm still doing researching trying to figure out if I can remove the valve body without taking the transmission completely out. This is my daily the can runs fine just always goes into limp mode at a light I would turn it off and then on so it would go away.

    Please someone give me their .02 I know I didn't put in a lot of information or haven't really shown effort of testing it yet but just need to hear experiences. I just caught myself looking for a 5spd DSM to just swap everything onto(I really wanna keep her ) ...
     

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