DTC P1811. Oldsmobile Alero 2001

For 1990-2009 cars only

Makes 🢒 Oldsmobile 🢒 2001 🢒 Alero 🢒 Body and Accessories 🢒 Body Control System 🢒 DTC P1811

DTC P1811 2.4 L and 3.4 L

Master Electrical Component List
Automatic Transmission Controls Schematics LD9
Automatic Transmission Controls Schematics LA1
OBD II Symbol Description Notice

Circuit Description

The PCM modifies the transmission line pressure through the pressure control (PC) solenoid valve, in order to control shift execution time and shift consistency. The PCM monitors various inputs, and modifies the shift execution and timing by applying a calculated duty cycle to the PC solenoid valve. The PCM alters the shifting based on driving habits, transmission load, and internal transmission condition.

When the PCM detects long shifts that cannot be shortened by shift adapts during the same ignition cycle, then DTC P1811 sets. DTC P1811 is a type C DTC.

Conditions for Running the DTC

•	The shift is adaptable.

•	The shift adapt is at its limit.

Conditions for Setting the DTC

The shift time is greater than 0.65 second twice during the same trip.

Action Taken When the DTC Sets

•	The PCM does not illuminate the malfunction indicator lamp (MIL).

•	The PCM commands maximum line pressure.

•	The PCM freezes transmission adapt functions.

•	The PCM records the operating conditions when the Conditions for Setting the DTC are met. The PCM stores this information as Failure Records.

•	The PCM stores DTC P1811 in PCM history.

Conditions for Clearing the DTC

•	A scan tool can clear the DTC.

•	The PCM clears the DTC from PCM history if the vehicle completes 40 warm-up cycles without a non-emission-related diagnostic fault occurring.

•	The PCM cancels the DTC default actions when the ignition switch is OFF long enough in order to power down the PCM.

Diagnostic Aids

Ask the customer about overloading the vehicle, exceeding the trailer-towing limit, or towing in Overdrive.

Test Description

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

This step tests for low fluid level, which can cause long shifts.

This step tests for low line pressure, which can cause long shifts.

DTC P1811 Maximum Adapt and Long Shift

Step

Action

Value(s)

Yes

Did you perform the Powertrain Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Engine Controls (2.4 L) or Diagnostic System Check - Engine Controls (3.4 L) in Engine Controls

Did you perform the Transmission Fluid Checking Procedure?

Go to Step 3

Go to Transmission Fluid Check

Install a Scan Tool .
Turn ON the ignition, with the engine OFF.

Important: Before clearing the DTC, use the Scan Tool in order to record the Failure Records. Using the Clear Info function erases the Failure Records from the PCM.

Record the DTC Failure Records.
Clear the DTC.
Use the Scan Tool snapshot mode in order to record the shift times.
Drive the vehicle in D4 in order to obtain 1-2, 2-3, and 3-4 shift times.
Record the shift times.

Did all the shift times exceed the specified value?

0.65 second

Go to Step 4

Go to Step 6

Did you perform the Line Pressure Check Procedure?

Go to Step 5

Go to Line Pressure Check

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 solenoid valve

•	Damaged PC solenoid valve

•	Stuck PC solenoid 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

Repair any of the above conditions as necessary.

Refer to Transmission Overhaul in Transmission Unit Repair Manual.

Did you complete the repair?

Go to Step 12

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

0.65 second

Go to Step 9

Go to Step 7

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

0.65 second

Go to Step 10

Go to Step 8

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

0.65 second

Go to Step 11

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 piston

•	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

•	Cracked or damaged driven sprocket support

•	Damaged sprag clutch (not holding)

•	2nd roller clutch damaged (not holding)

Repair the 1-2 shift circuit as necessary.

Refer to Transmission Overhaul in Transmission Unit Repair Manual.

Did you complete the repair?

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 (or not holding) sprag clutch

•	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 as necessary.

Refer to Transmission Overhaul in Transmission Unit Repair Manual.

Did you complete the repair?

Go to Step 12

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 as necessary.

Refer to Transmission Overhaul in Transmission Unit Repair Manual.

Did you complete the repair?

Go to Step 12

Change the AT fluid and filter.

Refer to Automatic Transmission Fluid Filter and Seal Replacement .

Inspect the transmission fluid for correct level.
Add new fluid as necessary.

Important: The Clear TAPS function will clear all adapt cells. This may affect transmission performance. The PCM will update the adapt cell values as the vehicle is driven.

Use the Scan Tool in order to perform the Clear TAPS function.

Did you complete the above procedures?

Go to Step 13

Perform the following procedure in order to verify the repair:

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 shifts.

•	Shift times must be less than 0.65 second.

Select Specific DTC.
Enter DTC P1811.

Has the test run and passed?

System OK

Go to Step 1