When I go up a steep grade my 4+3 manual trans will unlock/lock/unlock repeatedly. I then need to disable the overdrive by hitting the switch. On a level grade does not happen with AC off.

Today I was cruising on a long ride at 74 mph on a level road and flipped the OD on and incident occurred. Had not happened before but I generally never cruise over 67 mph with AC on. Typically 60-67 with AC on on my way to or away from home to office

My EBL .bin initially was an auto LO3. I dont recall changing anything to TCC constants/tables. I note the TCC values are MPH and TPS referenced.

Is there anything I need to change in my .bin to prevent the OD from unlocking?

Also it may be low on fluid as it has been a couple three years since I had it drained refilled. Could it be a failure of the unit with 126K miles?

 

Im sure its similar to $61 there is a unlock prevention at 75 mph.

 

I never looked at TCC before in my .bin till today.

I see TCC forced lock at 100 mph

Low GR(??) max TPS is 0

Low GR(??) MPH to lock is 1 mph

same min tps to coast unlock is 0

same MPH to unlock is 1 mph

I only use in high gear(4th)....

High GR max tps to coast unlock is 0 tps

Same MPH to lock is 2 mph

Same min TPS Coast to unlock is 0

Same MPH to unlock is 1 mph

TCC TPS delta for unlock is 100%

Lo GR to stay unlocked is 100pmh

Lo GR TPS to unlock is 100%

High GR tps% to stay unlocked is 100 mph

Hi GR tps% to unlock is 100

GR I presume is GEAR?

I am unsure if these are stock L03 auto values?

Something tells me my 4+3 is NOT affected by these values

My switch for TCC is set.

This one makes no sense to me "Same min TPS Coast to unlock is 0 "


I just spoke to my mechanic and he feels it is low on fluid......

 

IIRC the prevention I was thinking of is not listed in $61 and doesn't look like its on your ebl .bin. The tcc will be locked at 75mph -100mph unless at wot. you are correct gr is gear

 

LoGr is D (3rd gear)
HiGr is (D) (4th gear)

This is determined by the 4th gear switch in the valve body. If it is only doing it while in 4th gear, then change the HiGr stuff. On the WUD put shifter in D (3rd) and drive around, "Gear" should show "D". Now put it in OD and get up to speed so you can feel the trans shift into 4th, check WUD. "Gear" should now read "OD". If it does not change flag "HiGrH" and check again. If it doesn't know it's in "HiGr" it will use "LoGr" values.

EDIT: Are you running a OD trans or a TH350 w/ Lockup?

 

The OD unit on the 4+3 transmission can be controlled via the EBL. The TCC needs to be set up along the lines of the TH400 kick down parameters. It won't be exactly the same as the stock ECM control, but works well enough.

The TCC parameters are set up so that when the OD button is out the low gear TCC tables/parameters are used. And are set up so that OD will not be engaged.

When the button is in the high gear TCC tables/parameters are used. This allows the OD unit to engage at lower throttle settings, and dis-engage at higher throttle settings.


The overdrive button is going to the high-gear input of the ECM. This is used in the TCC logic. It is used to select between two different sets of tables.

You will need to set the TCC option flag:

Option Word 2 - Bit 7 - TCC

With that set the ECM will run the TCC logic. Flash this into the EBL ECM.

Also change the WUD Preferences Dialog, Gear Indicator entry for an automatic transmission.

Now key-on, engine-off and observe the WUD main display. In the center is a P/N, D, OD indicator. With the button out it should show D for drive. With the OD button pushed in it should now show OD.

If it does continue below. If it is the opposite change this option flag:

Option Word 2 - Bit 5 - HiGrH

Flash in that change and check again that the display shows OD with the OD button pushed in.

At this point the OD solenoid will be activated when the ECM thinks it is locking the TCC. And deactivate the OD solenoid when unlocking the TCC.

And, when the OD button is out, the ECM uses the low gear TCC parameters. And with the OD button in will use the high gear TCC parameters.

So setting the low gear parameters so that the TCC will never lock will disable OD when the button is out.

There are also some other odds & ends that need to be properly set, such as coast unlock and rapid TPS% movement unlock. Set the following parameters as shown:

TCC - Lock Enable CTS: -40 *C
TCC - Forced Lock: 255 MPH
TCC - LoGr Max TPS% Coast Unlock: 0%
TCC - LoGr Min TPS% Coast Unlock: 0%
TCC - LoGr MPH OK to Lock: 255 MPH
TCC - LoGr MPH to Unlock: 255 MPH
TCC - HiGr Max TPS% Coast Unlock: 0%
TCC - HiGr Min TPS% Coast Unlock: 0%
TCC - TPS% Opening/Closing Delta for Unlock: 100% for both entries
TCC - Relock Delays: 0 for all entries

The above settings will prevent OD from engaging when the button is out. And prevent OD from disengaging when the button is in on during a coast (low TPS%).

You now use the high gear parameters & tables to control OD. How you do this is up to you. They can be set up to follow the OD button (in or out). Or can be set up to exit OD with enough Throttle (TPS%).

Note that even though the tables are listed as "high hear", they are really "OD button is in" tables.

Set these two parameters to auto disengage OD when below the set speed:

TCC - HiGr MPH OK to Lock: 44 (use to set minimum MPH for OD)
TCC - HiGr MPH to Unlock: 45 (use to set minimum MPH for OD)

Use the following two tables to control how OD operates. To follow the button with no exit on a lot of throttle, set them to 100% (all entries).

Can also set the lower speeds to exit OD on heavy throttle, but stay in OD at the higher speeds.

TCC - HiGr TPS% to Stay Unlocked
TCC - HiGr TPS% to Unlock

Note that the 'TPS% to Unlock' table values should always be higher or the same as the values in the 'TPS% to Stay Unlocked' table.

Another listing of the parameters:

Note: parameters are in order of the XDF file.

Scalars:

TCC - Lock Enable CTS: -40
TCC - Forced Lock: 255
TCC - LoGr Max TPS% Coast Unlock: 0
TCC - LoGr MPH OK to Lock: 255
TCC - LoGr Min TPS% Coast Unlock: 0
TCC - LoGr MPH to Unlock: 255
TCC - HiGr Max TPS% Coast Unlock: 0
TCC - HiGr MPH OK to Lock: 44 (use to set minimum MPH for OD)
TCC - HiGr Min TPS% Coast Unlock: 0
TCC - HiGr MPH to Unlock: 45 (use to set minimum MPH for OD)

Flags:

"Option Word 2 - Bit 7 - TCC " option to be checked (set)
"Option Word 2 - Bit 5 - HiGrH" option to be checked (set)
"Option Word 2 - Bit 2 - DcTCC" option to be un-checked (clear)
"Option Word 3 - Bit 3 - TccHi" option to be un-checked (clear)

Tables:

TCC - TPS% Opening/Closing Delta for Unlock: 100%
TCC - Relock Delays: 0's
TCC - LoGr TPS% to Stay Unlocked: 0's
TCC - LoGr TPS% to Unlock: 0's
TCC - HiGr TPS% to Stay Unlocked: variable (use to set OD exit on heavy throttle)
TCC - HiGr TPS% to Unlock: variable (use to set OD exit on heavy throttle)

Note: the last two tables above set the TPS% threhold where OD is exited.
Be sure to retain the "TCC - HiGr TPS% to Stay Unlocked" table lower then the other table.

RBob.