DTC P1811 Maximum Adapt and Long Shift. Buick Century 1997

For 1990-2009 cars only

Makes 🢒 Buick 🢒 1997 🢒 Century 🢒 Transmission/Transaxle 🢒 Automatic Transaxle - 4T65-E 🢒 DTC P1811 Maximum Adapt and Long Shift

Automatic Transmission Components
Automatic Transmission Controls Schematics
OBD II Symbol Description Notice

Circuit Description

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

If the PCM detects the counter reaching two, then DTC P1811 sets. DTC P1811 is a type D DTC.

Conditions for Setting the DTC

One of the following fail cases is true two times.

Case 1

•	The 1-2 shift is longer than 0.65 seconds.

•	The 1-2 shift adapt has reached maximum pressure.

Case 2

•	The 2-3 shift is longer than 0.65 seconds.

•	The 2-3 shift adapt has reached maximim pressure.

Case 3

•	The 3-4 shift is longer than 0.65 seconds.

•	The 3-4 shift adapt has reached maximim pressure.

Action Taken When the DTC Sets

•	The PCM commands maximum line pressure.

•	The PCM disables shift adapts.

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

Conditions for Clearing the DTC

•	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

•	Inspect for possible vehicle overloading, exceeding trailer towing limit, or towing in overdrive.

•	If you performed a transmission overhaul, use the scan tool to clear all adapts.

Test Description

The numbers below refer to the step numbers on the diagnostic table.

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.

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.

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.

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.

DTC P1811 Maximum Adapt and Long Shift

Step

Action

Value(s)

Yes

Was the Powertrain On-Board Diagnostic (OBD) System Check performed?

Go to Step 2

Go to A Powertrain On Board Diagnostic (OBD) System Check

Have you performed the transmission fluid checking procedure?

Go to Step 3

Go to Transmission Fluid Check

Install the Scan Tool ®.
Turn the ignition switch to the Run position.
The engine is not running.

Important: Use the scan tool to record the failure records, because when you clear the DTCs, the Clear Info function will erase this data.

Record P1811 failure records.

Are any of the following DTCs set: P0120, P0121, P0122, P0123, P1121, P1122, P1524, P0502, P0503, P0711, P0712 or P0218?

Go to Step 4

Go to Step 5

Diagnose those DTCs first.

Is the diagnosis and repair complete?

Go to Step 14

Use the scan tool snapshot mode in order to record the shift times.
Drive the vehicle in D4 in order to obtain a 1-2, a 2-3, and 3-4 upshift.
Record the shift times.

Did all the shift times exceed the specified value?

0.65 seconds

Go to Step 6

Go to Step 8

Perform the line pressure check.

Refer to Line Pressure Check .

Is the line pressure within specifications

Go to Diagnostic Aids

Go to Step 7

Inspect the transmission for the following conditions:

•	Low fluid level caused by external leaks

•	Clogged fluid filter

•	Out-of-position fluid filter

•	Internal fluid passage leaks

•	Casting porosity or damage

•	Damaged gasket or spacer plate

•	Out-of-position gasket or spacer plate

•	Contaminated PC Sol. Valve

•	Damaged PC Sol. Valve

•	Stuck PC Sol. Valve

•	Stuck pressure regulator valve train

•	Leaking pressure regulator valve train

•	Stuck torque signal valve train

•	Leaking torque signal valve train

•	Leaking oil pump

•	Damaged oil pump

•	Inadequate oil pump suction

•	Oil pump cavitation

Refer to Transmission Overhaul , in Unit Repair.

Did you find and correct the condition?

Go to Step 14

Did the 1-2 shift time exceed the specified value?

0.65 seconds

Go to Step 9

Go to Step 10

Inspect the 1-2 shift circuit for the following conditions:

•	Leaking 1-2 accumulator piston seals

•	Rolled 1-2 accumulator piston seals

•	Cut 1-2 accumulator piston seals

•	Leaking 2nd clutch piston seals

•	Rolled 2nd clutch piston seals

•	Cut 2nd clutch piston seals

•	Burned 2nd clutch plates

•	Damaged 2nd clutch plates

•	Broken 2nd clutch springs

•	Out-of-position 2nd clutch springs

•	Damaged 2nd clutch pistons

•	Leaking driven sprocket support seals

•	Damaged driven sprocket support seals

•	Internal fluid passage leaks

•	Casting porosity or damage

•	Damaged gasket or spacer plate

•	Out-of-position gasket or spacer plate

•	Slipping forward clutch

•	Damaged sprag clutch (not holding)

•	2nd roller clutch damaged (not holding)

Repair the 1-2 shift circuit.

Refer to Transmission Overhaul , in Unit Repair.

Did you find and correct the condition?

Go to Step 14

Did the 2-3 shift time exceed the specified value?

0.65 seconds

Go to Step 11

Go to Step 12

Inspect the 2-3 shift circuit for the following conditions:

•	Leaking 2-3 accumulator piston seals

•	Rolled 2-3 accumulator piston seals

•	Cut 2-3 accumulator piston seals

•	Leaking direct clutch piston seals

•	Rolled direct clutch piston seals

•	Cut direct clutch piston seals

•	Burned direct clutch plates

•	Damaged direct clutch plates

•	Broken direct clutch springs

•	Out-of-position direct clutch springs

•	Damaged direct clutch pistons

•	Leaking driven sprocket support seals

•	Damaged driven sprocket support seals

•	Damaged driven sprocket support

•	Damaged sprag clutch (not holding)

•	Internal fluid passage leaks

•	Casting porosity or damage

•	Damaged gasket or spacer plate

•	Out-of-position gasket or spacer plate

Repair the 2-3 shift circuit.

Refer to Transmission Overhaul , in Unit Repair.

Did you find and correct the condition?

Go to Step 14

Did the 3-4 shift time exceed the specified value?

0.65 seconds

Go to Step 13

Inspect the 3-4 shift circuit for the following conditions:

•	Leaking 3-4 accumulator piston seals

•	Rolled 3-4 accumulator piston seals

•	Cut 3-4 accumulator piston seals

•	Leaking intermediate/4th servo piston seals

•	Rolled intermediate/4th servo piston seals

•	Cut intermediate/4th servo piston seals

•	Burned intermediate/4th band

•	Out-of-position intermediate/4th band

•	Damaged intermediate/4th band

•	Slipping intermediate/4th band

•	Internal fluid passage leaks

•	Casting porosity or damage

•	Damaged gasket or spacer plate

•	Out-of-position gasket or spacer plate

•	Slipping direct clutch

•	Damaged intermediate/4th servo pin

•	Seized intermediate/4th servo pin

•	Damaged intermediate/4th servo piston

•	Cracked intermediate/4th servo cover

•	Leaking intermediate/4th servo cover

Repair the 3-4 shift circuit.

Refer to Transmission Overhaul , in Unit Repair.

Did you find and correct the condition?

Go to Step 14

In order to verify your repair, perform the following procedure:

Select DTC.
Select Clear Info.
Operate the vehicle under the following conditions:

•	Drive the vehicle in D4 in order to obtain 1-2, 2-3, and 3-4 upshifts.

•	Shift times must be less than 0.65 seconds.

Select Specific DTC. Enter DTC P1811.

Has the test run and passed?

System OK

Begin the diagnosis again. Go to Step 1