GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Buick 🢒 2007 🢒 Lucerne 🢒 DTC 🢒 DTC P1811

Object Number: 1227651 Size: MF
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 second and the adaptive modifier cannot shorten this time, then a counter increases by one.

If 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.

DTC Descriptor

This diagnostic procedure supports the following DTC:

DTC P1811 Maximum Adapt and Long Shift

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 second, 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.

  1. This step inspects components that may cause low line pressure.

    2.

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

    3.

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

    4.

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

Step

Action

Value(s)

Yes

No

1

Did you perform the Diagnostic System Check - Vehicle?

--

Go to Step 2

Go to Diagnostic System Check - Vehicle

2

Did you perform the Transmission Fluid Checking Procedure?

--

Go to Step 3

Go to Transmission Fluid Check

3
  1. Install a scan tool.
  2. Turn ON the ignition with the engine OFF.

    3. Important: Before clearing the DTCs, use the scan tool in order to record the Failure Records for reference. Using the Clear DTC Information function will erase the stored Failure Records from the PCM.

  3. Record the Failure Records.
  4. Clear the DTCs.

Are any of DTCs P0120, P0220, P0218, P0502, P0503, P0711 or P0712 also set?

--

Go to Step 4

Go to Step 5

4

Diagnose the above DTCs first.

Is the diagnosis and repair complete?

--

Go to Step 14

--

5
  1. Use the scan tool snapshot mode in order to record the shift times.
  2. Drive the vehicle in D4 in order to obtain a 1-2, 2-3 and 3-4 upshift.
  3. Record the shift times.

Did all the shift times exceed the specified value?

0.65 second

Go to Step 6

Go to Step 8

6

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

7

Inspect the transmission for the following conditions:

    • Fluid level low
        Refer to Transmission Fluid Check .
    • Oil filter and seal missing, plugged or damaged
    • Spacer plate and gasket damaged or not assembled correctly
    • 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 .
    • Oil pump assembly damaged or missing components
        Refer to Transmission Fluid Pump Disassemble .

Refer to Incorrect Line Pressure .

Did you complete the repair?

--

Go to Step 14

--

8

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

0.65 second

Go to Step 9

Go to Step 10

9

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 .
    • Forward servo assembly damaged or not assembled correctly
        Refer to Forward Servo Removal .
    • Oil pump assembly damaged or missing components
        Refer to Transmission Fluid Pump Disassemble .
    • Spacer plate and gaskets damaged or not assembled correctly
    • Driven sprocket support seals damaged or missing
    • Second clutch piston and seal assembly binding or damaged
    • Second clutch fiber and steel plates not assembled correctly, burned or damaged
    • Second clutch spring assembly damaged or not assembled correctly
        Refer to 2nd Clutch Disassemble .
    • Forward band burned, damaged or not assembled correctly
    • 1-2 support roller clutch assembly damaged or not assembled correctly
        Refer to 1-2 Support Roller Clutch Disassemble .

Did you complete the repair?

--

Go to Step 14

--

10

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

0.65 second

Go to Step 11

Go to Step 12

11

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 .
    • Oil pump assembly damaged or missing components
        Refer to Transmission Fluid Pump Disassemble .
    • Spacer plate and gaskets damaged or not assembled correctly
    • Driven sprocket support seals damaged or missing
    • Third clutch piston seal rolled or damaged
    • Third clutch piston damaged or not assembled correctly
    • Third clutch fiber and steel plates not assembled correctly, burned or damaged
    • Third clutch spring assembly damaged or not assembled correctly
        Refer to Input and 3rd Clutch Disassemble .
    • Third sprag clutch assembly damaged or not assembled correctly
        Refer to Input and 3rd Clutch Pawl Disassemble .

Did you complete the repair?

--

Go to Step 14

--

12

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

0.65 second

Go to Step 13

Go to Diagnostic Aids

13

Inspect the transmission for the following conditions:

    • Oil pump assembly damaged or missing components
        Refer to Transmission Fluid Pump Disassemble .
    • Spacer plate and gaskets damaged or not assembled correctly
    • 3-4 accumulator piston seals rolled or damaged
    • 3-4 accumulator piston and pin missing, binding or damaged
        Refer to Case Cover Components Inspection .
    • Fourth clutch piston seal rolled or damaged
    • Fourth clutch piston damaged, not assembled correctly or seized
    • Fourth clutch fiber and steel plates not assembled correctly, burned or damaged
        Refer to 4th Clutch Components Removal .
    • Fourth clutch spring assembly damaged or not assembled correctly

Did you complete the repair?

--

Go to Step 14

--

14
  1. Change the AT fluid and filter.
  2. Inspect for correct transmission fluid level.

    3. Refer to Transmission Fluid Check .

  3. Add new AT fluid as necessary.

    4. Important: The Clear TAP 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.

  4. Using the scan tool, perform the Clear TAP function.

Did you complete the above procedure?

--

Go to Step 15

--

15

Perform the following procedure in order to verify the repair:

  1. Select DTC.
  2. Select Clear DTC Information.
  3. Drive the vehicle in D4.
  4. 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

16

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 - Vehicle

System OK