Transmission "Limp Mode": What is is, and what is known, so far. *

[lafrad]

I decided to put some information together as to what Transmission "Limp mode" or "Tranny Protection Mode" is, and how it applies.
This is specific for the 5-speed Automatic transmission in LX vehicles.



5.7L Stock TCM, ALL Flashes: Shift between 5500 and 5800, "Tranny Protection Mode" (Limp mode) around 6000 rpm.
With engine upgrades, and low traction, the Stock TCM may NOT shift fast enough (in "D" or "Autostick), and you may hit Limp Mode when tires spin.
Newer TCM Flashes shift "Faster", and are more difficult to force into Limp Mode.



5.7L Superchips TCM, All Flashes: Shift around 6250, "Tranny Protection Mode" (Limp Mode) around 6400 rpm.
With engine upgrades, and low traction, the Superchips TCM may NOT shift fast enough (in "D" or "AutosticK), and you may hit Limp Mode when tires spin.
Newer TCM Flashes shift "Faster", and are more difficult to force into Limp Mode. I have not seen the newest "AK" flash hit limp mode in my vehicle.


6.1L TCM, All Flashes: Shift around 6250, "Tranny Protection Mode" (Limp Mode) around 6400 rpm.
I have not heard of limp mode in "D" with this setup. See below for details on "Autostick" issues here.


Fast56K Custom Flash: Shift around 6400, "Tranny Protection Mode" (Limp Mode) unknown.
I have not heard reports of Limp mode, at all, with this setup.


3.5L Transmissions: Unknown.

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"Paddle Kick" - Superchips option - Newest SRT8 TCM TSB:
Autostick shifts at Stock Shift Points at WOT. Same "Limp Mode" issues as stated above for "D" operation

"Paddle Hold" - Superchips option - Older SRT8 TCM Operation:
Autostick will NEVER shift unless you tell it to. If the "Tranny Protection Mode" is at an RPM that is LOWER than the engine rev limiter, you WILL hit tranny protection mode BEFORE the Rev Limiter.


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Feel free to post more information with your personal experiences... we can update these topics as we go.

[Youngz1]

I noticed I can't hit the redline EVER! Do you know why this is?

[fnkychkn]

limp-home mode as described in fsm:

EMERGENCY RUNNING FUNCTION

In order to ensure a safe driving state and to prevent damage to the automatic transmission, the TCM control module switches to limp-home mode in the event of critical faults. A diagnostic trouble code (DTC) assigned to the fault is stored in memory. All solenoid and regulating valves are thus de-energized.
The net effect is:

The last engaged gear remains engaged.
The modulating pressure and shift pressures rise to the maximum levels.
The torque converter lockup clutch is deactivated.In order to preserve the operability of the vehicle to some extent, the hydraulic control can be used to engage 2nd gear or reverse using the following procedure:

Stop the vehicle.
Move selector lever to "P".
Switch off engine.
Wait at least 10 seconds.
Start engine.
Move selector lever to D: 2nd gear.
Move selector lever to R: Reverse gear.The limp-home function remains active until the DTC is rectified or the stored DTC is erased with the appropriate scan tool. Sporadic faults can be reset via ignition OFF/ON.

[06SilverSteel]

Good info guys.....hey fnky, how much $$$ are stock 5.7 TCM's, and are they hard to come by?

[fnkychkn]

Good info guys.....hey fnky, how much $$$ are stock 5.7 TCM's, and are they hard to come by?
04896395AH $264.00 cdn. not many but they are available.
04692390AF $262.00 cdn. lots available at most parts depots.
04692392AI $306.00 cdn. currently back ordered.

[06SilverSteel]

Thanks a bunch fnky! I will be looking into these.

[lafrad]

I wonder... is the 395 from '07 models?

[newskoolcharger]

iam glad u guys put this on here i have a 07 r/t with 50,000 miles and the trans already went up the dealer replaced it and 3 weeks later it is not shifting right its hanging up in gear and knocks when you start it up when its cold with it hanging up is that the limp mode ??????????