4T80-E Automatic Transaxle
DTC P1811
Circuit Description
Important: Refer to the 2007 Transmission Unit Repair (TURM) for Fluid Flow illustration.
An adaptive modifier modifies the transmission line pressure. The adaptive modifier controls the shift execution time. This DTC monitors 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 iterates.
DTC P1811 sets when this counter reaches its limit. DTC P1811 is a type C DTC.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC P1811 Maximum Adapt and Long Shift
Conditions for Running the DTC
An adaptable shift has occurred.
Conditions for Setting the DTC
One of the following conditions occurs twice during the same trip:
Condition 1
* The 1-2 shift is longer than 0.65 second.
* The 1-2 shift adapt has reached its limit.
Condition 2
* The 2-3 shift is longer than 0.65 second.
* The 2-3 shift adapt has reached its limit.
Condition 3
* The 3-4 shift is longer than 0.65 second.
* The 3-4 shift adapt has reached its limit.
Action Taken When the DTC Sets
* The TCM does not request the engine control module (ECM) to illuminate the malfunction indicator lamp (MIL).
* The TCM commands maximum line pressure.
* The TCM freezes transmission adaptive functions.
* The TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as Failure Records.
* The TCM stores DTC P1811 in TCM history.
Conditions for Clearing the DIC/DTC
* The TCM clears the DIC message when the condition no longer exists.
* A scan tool can clear the DIC/DTC.
* The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without a non-emission-related diagnostic fault occurring.
* The TCM cancels the DTC default actions when the fault no longer exists and the DTC passes.
Diagnostic Aids
* Ask the customer about overloading the vehicle, exceeding the trailer-towing limit, or towing in Overdrive.
* Ensure that the TCM has the latest calibration update.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
3. This step reviews the 1-2 adapt cells. If the pressure readings match or exceed the value listed in the value column, then the TCM modifies the base line pressure on a 1-2 shift. This modification adjusts the holding effort of a clutch or band.
4. This step reviews the 2-3 adapt cells. If pressure readings match or exceed the value listed in the value column, then the TCM modifies the base line pressure on a 2-3 shift. This modification adjusts the holding effort of a clutch or band.
5. This step reviews the 3-4 adapt cells. If pressure readings match or exceed the values listed in the value column, then the TCM modifies the base line pressure on a 3-4 shift. This modification adjusts the holding effort of a clutch or band.
6. This step inspects or repairs any of the components listed. A faulty component may lead to a maximum adapt and long shift during a 1-2 upshift.
7. This step inspects or repairs any of the components listed. A faulty component may lead to a maximum adapt and long shift during a 2-3 upshift.
8. This step inspects or repairs any of the components listed. A faulty component may lead to a maximum adapt and long shift during a 3-4 upshift.
9. This step inspects components located within the valve body, if the fluid pressure gage readings do not match the commanded PC solenoid valve current to line pressure located in the value column.
Step 1 - Step 6:
Step 7 - Step 8:
Step 9 - Step 11:
Step 12 - Step 14:
