QUESTION ON TCC LOCK UP

[MIKE MOG]

I HAVE A QUESTION ON TCC LOCK UP. I HAD MY TRUCK ON THE FREEWAY TODAY AND IT WAS UP TO OPPERATING TEMP AND IN OD. I DECIDED TO HIT THE BRAKE PEDAL AND SEE IF I COULD GET TCC LOCK UP TO DISENGAGE. THE RPM DID NOT CHANGE, MADMATT HAS BEEN WORKING WITH ME ON A NOISE/VIBERATION AND SENT ME A BULLETION NUMBER. ANYWAY IS THE ALLISON LIKE THE 4T80E OR THE 4L80E WHEN YOU HIT THE BRAKE PEDAL THE CONVERTER SHOULD UNLOCK AND RPMS SHOULD COME UP? I NEVER TOOK MY FOOT OFF OF THE BRAKE PEDAL AND NEVER GOT THE RPMS TO CHANGE.
THANKS, MIKE

[DmaxMaverick]

The Allison's control of the TCC is not like previous/other trannies. The brake pedal will not cause an unlock, or coast mode. Unlock will only occur when the speed drops below the preset. The only way to get the TCC to unlock above the preset when on compression is with a Tech II or other capable scanner.

[madmatt]

Hey Mike! Yeah the Allison is a hole different breed of steed!! Throw everything you know about the 4Ls out the window when dealing w/ one of these. On GM Dealerworld SI look @ the bottom of the page under Allison transmissons Diag info and procedures. Thres a lot of good info that should help w/ diagn' the TCC and help explain operation.

[MIKE MOG]

THANKS GUY'S WITH OUT YOU OR THIS WEB SITE ID BE LOST. ILL GO TO SI ON MONDAY MATT. THANKS AGAIN GUYS.
MIKE