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Thread: 86 Vette with 94 LT1 Help NEEDED!!

  1. #1
    Carb and Points!
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    86 Vette with 94 LT1 Help NEEDED!!

    Hello, been lurking here for a few weeks now From South Carolina.
    Here is my project:
    Bought a 86 vette 10+ years ago had minor front end damage while working on body car was left out one night and the block crack on both sides(I hadn't had the car a week) well the car then set for a few yrs found 94 corvette motor and tranny with 43,000 miles on it, sent computer and wiring harness out for programming and rewiring got a call from the shop saying he couldn't flash corvette pcm but had one that would work (16188051) everything hooked up car fired right up and I have drove the car around the yard from storage to shop quite a few times finally finished the body and paint then it set couple more yrs finished the interior put insurance and tag on it drove down the road and it acted like the tranny was slipping rebuilt tranny with new valve body still same results.
    Got doing some research found the numbers on computer where from 1995 Caprice thought maybe that was the problem being 95 pcm was looking for PWM solenoid which isn't there.
    Ordered a cable and software flashed 94 Z28 A4 bin, disabled vatts lowered fan temps fired car up went for a drive same results but now I have some trouble codes to work with 1st one DTC 97 vss output, installed 1k 1/2 watt resistor corrected that one.
    At the vss sensor there is a pig tail which spilts off and goes to the factory digital speedo which is working.
    Then started getting DTC 24 low output when this happens tranny goes in limp mode 3rd gear next trip out carried lap top with me and using EEHack Datalog under speed had rpm but no MPH, also noticed when playing with the controls I could here solenoids click when going through the gears on Tranny controls but when engaging TCC on to off to auto never heard solenoid click hooked wire up to blue connector pin 11 went to ground with ignition on could here solenoid click, thought must be outputs on pcm not working ordered Refurbished 16188051 pcm flashed a different 94 Z28 bin, have not drove car yet (Raining here right now) but with car jacked up in shop still have no MPH on EEHack datalog but factory speedo working just fine also noticed when trying to control TCC from EEHack still not getting solenoid function and picked up a new DTC 83 TCC/PWM A4 Trans.

    Sorry for the Xlong post hope somebody was able to finish the story and has some ideals.
    Thanks Terry.

  2. #2
    Fuel Injected! steveo's Avatar
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    hey terry welcome

    At the vss sensor there is a pig tail which spilts off and goes to the factory digital speedo which is working.
    TCC aside, if eehack doesn't log any speed, neither does your ECM, and that means your transmission will never work properly (a bunch of the other code wont either, it needs to know whether the vehicle is moving or not)

    need more details about that 'splitter'.. something is going on there i'll bet. try temporarily wiring the vss straight to the ECM and see if it behaves

  3. #3
    Carb and Points!
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    Quote Originally Posted by steveo View Post
    hey terry welcome



    TCC aside, if eehack doesn't log any speed, neither does your ECM, and that means your transmission will never work properly (a bunch of the other code wont either, it needs to know whether the vehicle is moving or not)

    need more details about that 'splitter'.. something is going on there i'll bet. try temporarily wiring the vss straight to the ECM and see if it behaves
    Update: harness from vss to pcm is good, jumped ground for TCC solenoid and it clicks so ran toggle switch and moving @ 55mph made switch and TCC engages but still can not control it from EEHack?
    What has been done is the gear and speed sensor from the 86 transmission where put on the 4l60e so the speedo would work and some code changed that was suppose to work for the pcm? while driving i noticed at about 53-54 mph datalog started picking up mph.
    speedometer scaler -base = 2
    speedometer scaler -Divisor = .8144
    speedometer scaler - scan tool =40.951
    stopped vehicle vss pulse delay-= 366.46
    speedometer scaler driveshaft PPR-=4.002

    I changed pulse delay to 128.46, scan tool to 35.115 and drive shaft PPR to 1.905 now around 25 mph the datalog is picking up mph and it is right on with speedo did not get dtc24 this time but easing into gas it shifts way to fast when i get into the gas it shifts like it should. I may play with those settings a little more but have ordered the right reluctor and sensor but that is going to mess the speedo up. what options do I have for getting the speedo right and what could be going on with TCC?
    Thanks for any input.
    Last edited by ttbone72; 2 Weeks Ago at 02:36 PM. Reason: added scan tool change

  4. #4
    Carb and Points!
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    Installed the Right VSS and reluctor ring have mph on datalog now speedo is way out but expected that found a universal speedo signal interface that should fix that. Transmission shifted fairly well But still no TCC lockup, toggle switch I have rigged up still engages it, but PCM will not any Ideals?

  5. #5
    Fuel Injected! sturgillbd's Avatar
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    Do you have the 12V signal coming from the brake switch feeding the PCM pin C14? If the PCM doesn't have this signal, the tcc will not lock. PCM thinks the brakes are being applied.

    Brian

  6. #6
    Carb and Points!
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    Quote Originally Posted by sturgillbd View Post
    Do you have the 12V signal coming from the brake switch feeding the PCM pin C14? If the PCM doesn't have this signal, the tcc will not lock. PCM thinks the brakes are being applied.

    Brian
    That was it!! Replaced brake booster Saturday evening when I was finished the brake lights stayed on adjusted switch, hooked up laptop and could control TCC solenoid haven't test drove car yet Rained all weekend but feel it will engage fine when i do get to take it back out.
    Thanks for the reply.

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