MSgpio.com read only forums (Jan.15,2018)

So here are the instructions from Jake's Performance on my 4L80E trans brake:

Wiring the transbrake consists of tying into the B wire, typically yellow wire, that controls the B (2-3) shift solenoid on the control harness going to the transmission.
Go through a momentary switch to a good ground.
Activating the switch in the manual low position will engage the transbrake.

PCM tuning required. You must program the controller to not allow a 1-2 shift while the transmission is in manual low.
The transbrake will engage if the PCM commands an upshift causing parts damage or injury.
We also do not recommend downshifting into manual low while moving.
Our transbrake design allows for very fast transbrake setup and release times as well as minimizes circuit volume in several circuits in the transmission. This makes it very quick acting and capable of holding more HP on the transbrake and clutches. As a byproduct of the design, it applies the low gear band quicker than the intermediate (2nd) gear clutches can release, creating a slight bind on a 2-1 downshift. We can alter this for those that need the ability to do 2-1 downshifts.

Any suggestions on how to set this up properly so Megashift doesn't cause the trans to kill itself

shaodome,

It sounds like you want to prevent the 1-2 shift using the gear lever. Is "manual low" normally 1st gear or second gear (1.e. first and second gears)?

If manual low is normally first gear, the controller will not shift to second (unless you have rev limit checking on and you exceed the limit, but you can turn the limiting off or set the limit to an out-of-range value).

If manual low is second gear normally (and possibly allows shifts to 1st), you could tell MShift that the gear lever input pattern for manual low is the pattern for first gear (even though it might normally be 1st and 2nd in the OEM scheme). Then the trans won't shift to second (with the same caveat about rev limiting, which you can turn off if you like). This would mean you wouldn't have a lever position that selected only 1st and 2nd, but that's what you want if I understand correctly.

The other thing you can do is shift manually using the shift buttons.

BTW, I am thinking of implementing a third shift m,ode (besides auto and manual) that would be a lever follow mode (except possibly in the highest gear lever position). That seems to be what a number of people are looking for (instead of using the shift buttons). This will be released in the code update thread when it is ready for prime time.

Lance.

Thanks Lance.

I noticed something odd about manual low....when I moved the wratchet shifter all the way down to what should be 1st, the gear indicator still showed 0. It definitely was in first as I was able to drive the car and it didn't shift out of first, but then when I wratched up to 2nd, the car didn't shift as Megashift now was commanding first gear?

the gear indicator still showed 0

Shaodome,

Which gear indicator? The current_gear, manual_gear or target_gear in tunerstudio? Or maybe something else?

What code version are you using?

Lance.

I'm using the current stable release code.

The "current gear" gauge is the one I am referring to.

MSQ? datalog?

Attached is the MSQ. I was driving the car for the first time last night and noticed something weird.

If I used the wratchet shifter to go down into 1st gear and then wratcheted up back into drive, it would not shift gears. It was not until I came to a complete stop and then put it in Drive (4) that it would shift normal again. I don't have any datalogs YET but I will hopefully by tonight.

shaodome wrote:Thanks Lance.

I noticed something odd about manual low....when I moved the wratchet shifter all the way down to what should be 1st, the gear indicator still showed 0. It definitely was in first as I was able to drive the car and it didn't shift out of first, but then when I wratched up to 2nd, the car didn't shift as Megashift now was commanding first gear?

Found the problem.....I was checking to see if I installed the 330ohm pullup (I did) and noticed that on the build instructions the diode goes the other way for the circuit on input 1. Swapped it and it now recognizes all 4 gears