P1811

Diagnostic Chart:

CIRCUIT DESCRIPTION

IMPORTANT: Refer to Transmission and Drivetrain for Fluid Flow illustration.

An adaptive modifier modifies the transmission pressure. The adaptive modifier controls the shift execution time. This test checks the time required to accomplish the shift. If the shift takes longer than 0.55 seconds, and the adaptive modifier cannot shorten this time, then a counter increases by one.

DTC P1811 sets when this counter reaches its limit. DTC P1811 is a Type C DTC.

CONDITIONS FOR SETTING THE DTC

^ No TP DTCs P0121, P0122 or P0123.

^ No Transmission Fluid Overtemperature DTC P0218.

^ No VSS DTCs P0502 or P0503.

^ No Automatic Transmission Fluid Temperature (TFT) DTCs P0711, P0712 or P0713.

^ The transmission fluid temperature is greater than 50°C (122°F).

^ The vehicle speed is greater than 16 km/h (10 mph).

^ The throttle angle is greater than 15.7 degrees.

Failure Criteria:

Case 1

^ The 1-2 shift is longer than 0.55 seconds.

^ The 1-2 shift adapt has reached its limit.

Case 2

^ The 2-3 shift is longer than 0.55 seconds.

^ The 2-3 shift adapt has reached its limit.

Case 3

^ The 3-4 shift is longer than 0.55 seconds.

^ The 3-4 shift adapt has reached its limit.

ACTION TAKEN WHEN THE DTC SETS

^ The PCM does not illuminate the Malfunction Indicator Lamp (MIL).

^ SERVICE VEHICLE SOON displays on the Driver Information Center (DIC).

^ The PCM commands maximum line pressure.

^ The PCM disables steady state adapts.

^ The PCM disables upshift adapts.

^ The PCM disables garage shift adapts.

^ DTC P1811 is stored in the PCM history.

CONDITIONS FOR CLEARING THE DIC/DTC

^ The PCM turns OFF the DIC after three consecutive trips without a failure reported.

^ Shift times are less than 0.55 seconds for three occurrences.

^ A scan tool can clear the DTC from the PCM history. The PCM clears the DTC from the PCM history if the vehicle completes 40 warm-up cycles without a failure reported.

^ The PCM cancels the DTC default actions when the fault no longer exists and the ignition is OFF long enough in order to power down the PCM.

DIAGNOSTIC AIDS

^ Ensure that the PCM has the latest update.

^ If a transmission overhaul was performed, use the scan tool to clear all adapts.

TEST DESCRIPTION

The numbers below refer to the step numbers on the Diagnostic Table.

5. Assume that DTC P1811 is the only code set. This step reviews the 1-2 adapt cell along with shift time. If the pressure readings match or exceed the parameters listed in the value column, then the PCM modifies the base line pressure on a 1-2 shift. This modification adjusts the holding effect of a clutch or band.

6. This step reviews the 2-3 adapt cell along with shift time. If pressure readings match or exceed the parameters listed in the value column, then the PCM modifies the base line pressure on a 2-3 shift. This modification adjusts the holding effort of a clutch or band.

7. This step reviews the 3-4 adapt cell along with shift time. If pressure readings match or exceed the parameters listed in the value column, then the PCM modifies the base line pressure on a 3-4 shift. This modification adjusts the holding effort of a clutch or band.

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 1-2 upshift.

9. 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.

10. 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.

11. This step inspects components located within the valve body, if the fluid pressure gauge readings do not match the commanded PC Sol. Valve current to line pressure located in the value column.