HYDRA-MATIC 4T65-E (M15) Automatic Transmission Harsh Shift, Sets False DTC P1811 (Reprogram TCM)

Some customers may comment on harsh shift. Upon further investigation, the technician may find a DTC P1811 information stored in the Transmission Control Module (TCM) failure records and the TCM history.

DTC P1811 : Maximum Adapt and Long Shift

The transmission pressure is modified by an adaptive modifier, which controls the shift execution time. This diagnostic tests the time required to accomplish the shift. If the shift takes longer than 0.65 second and the adaptive modifier cannot shorten this time, then a counter increases by 1.

If the TCM detects a counter value of 2 during 1 trip or lower transmission shift adapt cells usually 1, 2, 3 have maximum adapt values, then DTC P1811 sets. DTC P1811 is a type C DTC.

If routine diagnosis using SI does not reveal any obvious cause for DTC P1811, a revised transmission calibration has been developed to address this issue. Reprogram the TCM using calibration part number 24247599. This calibration part number, or any that follow, is designed to address this concern. Do Not replace the TCM, transmission valve body or shift solenoids for this concern. Reprogram the TCM with an updated software calibration. This new service calibration is available on TIS2WEB using the Service Programming System (SPS). As always, make sure your Tech 2® is updated with the latest software version.

For vehicles repaired under warranty, use: