DTC P1811. Buick Regal 2003

For 1990-2009 cars only

Makes 🢒 Buick 🢒 2003 🢒 Regal 🢒 Engine 🢒 Engine Controls - 3.8L 🢒 DTC P1811

Master Electrical Component List
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 diagnostic tests 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 a counter value of 2 during one trip, then DTC P1811 sets. DTC P1811 is a type C DTC.

Conditions for Running the DTC

•	The shift is adaptable.

•	The 1-2, the 2-3 or the 3-4 shift adapt cell has reached its limit.

Conditions for Setting the DTC

The 1-2, 2-3 or 3-4 shift is longer than 0.65 seconds, twice in one 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 adaptive 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 possible overloading, exceeding the trailer towing limit, or towing in overdrive.

•	Ensure that the current PCM calibration is correct for the final drive ratio.

Test Description

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

This step inspects components that may cause low line pressure.

This step inspects or repairs components that may cause a maximum adapt and long 1-2 upshift.

This step inspects or repairs components that may cause a maximum adapt and long 2-3 upshift.

This step inspects or repairs components that may cause a maximum adapt and long 3-4 upshift.

Step

Action

Value(s)

Yes

Did you perform the Diagnostic System Check?

Go to Step 2

Go to Diagnostic System Check - Engine Controls in Engine Controls - 3.1L or Diagnostic System Check - Engine Controls in Engine Controls - 3.8L

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 DTCs, use the scan tool in order to record the Failure Records for reference. Using the Clear Info function will erase the stored Failure Records from the PCM.

Record the Failure Records.
Clear the DTCs.

Are any of DTCs P0121, P0122, P0123, P0218, P0502, P0503, P0711, P0712, P1121 or P1122 also set?

Go to Step 4

Go to Step 5

Diagnose the above 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, 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 Procedure.

Refer to the Line Pressure Check .

Is the line pressure within specifications?

Go to Diagnostic Aids

Go to Step 7

Inspect the transmission for the following conditions:

•	Fluid level low

Refer to Transmission Fluid Check in Transmission Unit Repair Manual.

•	Oil filter and seal missing, plugged or damaged

Refer to Automatic Transmission Fluid Filter and Seal Replacement .

•	Spacer plate and gasket damaged or misassembled

Refer to Control Valve Body and Spacer Plate Assemble in Transmission Unit Repair Manual.

•	PC solenoid valve damaged or contaminated

•	Pressure regulator valve line-up binding or damaged

•	Torque signal valve line-up binding or damaged

Refer to Control Valve Body Disassemble in Transmission Unit Repair Manual.

•	Oil pump assembly damaged or missing components

Refer to Transmission Fluid Pump Disassemble in Transmission Unit Repair Manual.

Refer to Incorrect Line Pressure .

Did you complete the repair?

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 transmission for the following conditions:

•	1-2 accumulator piston seals rolled or damaged

•	1-2 accumulator piston and pin missing, binding or damaged

Refer to Accumulator Components Disassemble in Transmission Unit Repair Manual.

•	Forward servo assembly damaged or misassembled

Refer to Forward Servo Removal in Transmission Unit Repair Manual.

•	Oil pump assembly damaged or missing components

Refer to Transmission Fluid Pump Disassemble in Transmission Unit Repair Manual.

•	Spacer plate and gaskets damaged or misassembled

Refer to Control Valve Body and Spacer Plate Assemble in Transmission Unit Repair Manual.

•	Driven sprocket support seals damaged or missing

Refer to Driven Sprocket Support Components Disassemble in Transmission Unit Repair Manual.

•	Second clutch piston and seal assembly binding or damaged

•	Second clutch fiber and steel plates misassembled, burned or damaged

•	Second clutch spring assembly damaged or misassembled

Refer to 2nd Clutch Disassemble in Transmission Unit Repair Manual.

•	Forward band burned, damaged or misassembled

Refer to 1-2 Support Drum and Forward Band Removal in Transmission Unit Repair Manual.

•	1-2 support roller clutch assembly damaged or misassembled

Refer to 1-2 Support Roller Clutch Disassemble in Transmission Unit Repair Manual.

Did you complete the repair?

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 transmission for the following conditions:

•	2-3 accumulator piston seals rolled or damaged

•	2-3 accumulator piston and pin missing, binding or damaged

Refer to Accumulator Components Disassemble in Transmission Unit Repair Manual.

•	Oil pump assembly damaged or missing components

Refer to Transmission Fluid Pump Disassemble in Transmission Unit Repair Manual.

•	Spacer plate and gaskets damaged or misassembled

Refer to Control Valve Body and Spacer Plate Assemble in Transmission Unit Repair Manual.

•	Driven sprocket support seals damaged or missing

Refer to Driven Sprocket Support Components Disassemble in Transmission Unit Repair Manual.

•	Third clutch piston seal rolled or damaged

•	Third clutch piston damaged or misassembled

•	Third clutch fiber and steel plates misassembled, burned or damaged

•	Third clutch spring assembly damaged or misassembled

Refer to Input and 3rd Clutch Disassemble in Transmission Unit Repair Manual.

•	Third sprag clutch assembly damaged or misassembled

Refer to Input and Third Sprag Clutches Disassemble in Transmission Unit Repair Manual.

Did you complete the repair?

Go to Step 14

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

0.65 seconds

Go to Step 13

Go to Diagnostic Aids

Inspect the transmission for the following conditions:

•	Oil pump assembly damaged or missing components

Refer to Transmission Fluid Pump Disassemble in Transmission Unit Repair Manual.

•	Spacer plate and gaskets damaged or misassembled

Refer to Control Valve Body and Spacer Plate Assemble in Transmission Unit Repair Manual.

•	3-4 accumulator piston seals rolled or damaged

•	3-4 accumulator piston and pin missing, binding or damaged

Refer to Case Cover Components Inspection in Transmission Unit Repair Manual.

•	Fourth clutch piston seal rolled or damaged

•	Fourth clutch piston damaged, misassembled or seized

Refer to Driven Sprocket Support Components Disassemble in Transmission Unit Repair Manual.

•	Fourth clutch fiber and steel plates misassembled, burned or damaged

Refer to 4th Clutch Components Removal in Transmission Unit Repair Manual.

•	Fourth clutch spring assembly damaged or misassembled

Refer to Driven Sprocket Support Components Disassemble in Transmission Unit Repair Manual.

Did you complete the repair?

Go to Step 14

Change the AT fluid and filter.
Inspect for correct transmission fluid level.

Refer to Transmission Fluid Check .

Add new AT fluid as necessary.

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

Using the scan tool, perform the Clear TAPS function.

Did you complete the above procedure?

Go to Step 15

Perform the following procedure in order to verify the repair:

Select DTC.
Select Clear Info.
Drive the vehicle in D4.
Observe Last Shift Time on the scan tool. Ensure that the 1-2, 2-3, and 3-4 shift times are less than 0.65 second.

Was each shift time less than 0.65 second?

Go to Step 16

Go to Step 2

With a scan tool, observe the stored information, capture info and DTC info.

Does the scan tool display any DTCs that you have not diagnosed?

Go to Diagnostic Trouble Code (DTC) List in Engine Controls - 3.1L or Diagnostic Trouble Code (DTC) List in Engine Controls - 3.8L

System OK