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Thread: TBI 16168625 to LT1 16188051 Swap No TCC lock up??

  1. #16
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    You're interrupting power to the PCM brake switch input? Light blue/black wire on pin C14. When I did my LT1 transplant I just put power to that wire. Works fine unless you're stepping on the brake while holding the throttle since the PCM is programmed to unlock the TCC at 0% TPS.

    I believe A12 is a PWM output to the EBTCM to tell it what torque or throttle percentage or something similar that the engine is producing. Pin A23 is a PWM signal back to tell the PCM how much to reduce the engine torque, by retarding the timing.

  2. #17
    Fuel Injected! bybyc5's Avatar
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    Quote Originally Posted by lionelhutz View Post
    You're interrupting power to the PCM brake switch input? Light blue/black wire on pin C14. When I did my LT1 transplant I just put power to that wire. Works fine unless you're stepping on the brake while holding the throttle since the PCM is programmed to unlock the TCC at 0% TPS.
    I did consider doing just that, leave a 12V direct input, but considering the pin is labeled brake switch signal, I figured the 12V signal it monitored needed to know when the brake pedal was depressed. Maybe during braking at speeds where the TCC in locked up, it is desirable to disengage the TCC? And mine does. If you touch the brake pedal on a steady cruise, that tachometer jumps up a 100 rpm or so, then re-engages when released.

    Not sure what the designers intentions were. No, I don't power brake this vehicle....have many others though !!

    Quote Originally Posted by LIONELHUTZ View Post
    I believe A12 is a PWM output to the EBTCM to tell it what torque or throttle percentage or something similar that the engine is producing. Pin A23 is a PWM signal back to tell the PCM how much to reduce the engine torque, by retarding the timing.
    Yes, this circuit has eluded me, however the little research I did led me to believe it was for the Traction Control Management ?? I know some F-bodies had them, mine ( My formula ) did not being an M6.

    I have also removed this from some Z-28's that did have the TCM. Not sure about any of the EBTCM circuit? But it appears to have no adverse effect on my truck without it.
    This LT1 swap into my truck was a major improvement drive-ability wise. My OE system was map based, and no MAT input. So the old 383 ran very well with some tweaking of the 16168625, with great mileage. Was going to go from $E6 to $OD and add the MAT circuit....But had a valve spring collapse and dropped an exhaust valve that ended that motor.

    So I had a spare LT1 motor "in stock" and rebuilt it a 383 with a 4x4 low rpm torque cam. Very happy with the result.

    So now I may be adding a lot of stuff to the for sale section to clear my shelf of several $E6 and $OD PCMs and all the TBI and TPI engine components accumulated over the past years. Complete TPI and TBI manifolds and engine brackets, etc.....Even have an LT1 intake manifold I drilled a hole in it to mount a distributor and run the LT1 initially with my $E6 PCM. But now it's 100% LT1. Opti and all.

    Thank you all for the help!!

    James
    04 Lightning Pullies n Tune CAI
    96 Formula WS-6 m6 383 LE3-Heads/GM847/N2O/ Ford 9" 4:33/Sus Work/Stickies/TunerProRT
    93 K1500 383 LT1 with Low RPM 4x4 torque cam

  3. #18
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    I've driven my car for a few years and haven't noticed any bad effects with the input simply connected to power.

    There is a traction control spark table. You can zero it out so the EBTCM input (A23) can't do anything.

  4. #19
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    Quote Originally Posted by lionelhutz View Post
    I've driven my car for a few years and haven't noticed any bad effects with the input simply connected to power.

    There is a traction control spark table. You can zero it out so the EBTCM input (A23) can't do anything.
    Not sure which brake switch setup his truck had from the factory as GM switched to a single brake switch on the newer models, but both setups have a 12V output that is switched off when the brake is activated. His factory TBI setup had the same input that could have been used without a relay. Even my old 1983 G20 van that came with electronic/vacuum cruise had a cruise control brake switch that doubled as a vacuum release valve that had the correct output to feed the PCM.

  5. #20
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    Quote Originally Posted by Fast355 View Post
    Not sure which brake switch setup his truck had from the factory as GM switched to a single brake switch on the newer models, but both setups have a 12V output that is switched off when the brake is activated. His factory TBI setup had the same input that could have been used without a relay. Even my old 1983 G20 van that came with electronic/vacuum cruise had a cruise control brake switch that doubled as a vacuum release valve that had the correct output to feed the PCM.
    That's good to know. I didn't see that feed. I did tap the feed that fed the brake lamp circuit.
    Thanks again.

    James
    04 Lightning Pullies n Tune CAI
    96 Formula WS-6 m6 383 LE3-Heads/GM847/N2O/ Ford 9" 4:33/Sus Work/Stickies/TunerProRT
    93 K1500 383 LT1 with Low RPM 4x4 torque cam

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