GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 1995 🢒 Cavalier 🢒 Transmission/Transaxle 🢒 Automatic Transaxle - 4T40-E 🢒 DTC P1811 Maximum Adapt and Long Shift

Object Number: 40585 Size: MF

Circuit Description

The Powertrain Control Module (PCM) modifies the transmission line pressure through the Pressure Control Solenoid Valve (PC Sol. 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 Sol. 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 D DTC.

Conditions for Setting the DTC

The shift time is greater than 1.8 seconds at maximum adapt, for a total of five times during the same ignition cycle.

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 shift adapts from being updated.
    • DTC P1811 is stored in the PCM history.

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
    • Ask the customer about overloading the vehicle, exceeding the trailer-towing limit, or towing in Overdrive.
    • If, after several unsuccessful attempts to gain accurate shift times, and an adapt can be made, reset adapts and operate the vehicle, in order to assure proper shifting.

Test Description

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

  1. This Step tests for low fluid level, which can cause delayed shifts.

    2.

  2. This Step tests for low line pressure, which can cause delayed shifts.

    3.

  3. When DTC P1811 sets, the PCM commands maximum line pressure and does not inhibit TCC engagement. This can lead to excessive heat build-up, causing the Torque Converter to "balloon." You must replace the Torque Converter.

P1811

Step

Action

Value(s)

Yes

No

1

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

--

Go to Step 2

Go to

Powertrain On Board Diagnostic (OBD) System Check in Engine Controls - 2.3L

2

Have you performed the transmission fluid checking procedure?

--

Go to Step 3

Go to Transmission Fluid Check

3
  1. Install the scan tool (tech 1) .
  2. With the engine OFF, turn the ignition switch to the RUN position.

    3. Important: Before clearing the DTCs, use the scan tool in order to record the Failure Records for reference. The Clear Info function will erase the data.

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

Did all the shift times exceed the specified value?

1.8 seconds

Go to Step 4

Go to Step 6

4

Perform the line pressure check.

Refer to Line Pressure Check .

Is the line pressure within specifications?

--

Go to Diagnostic Aids

Go to Step 5

5

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 Unit Repair.

Did you find and correct the condition?

--

Go to Step 11

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6

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

1.8 seconds

Go to Step 9

Go to Step 7

7

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

1.8 seconds

Go to Step 10

Go to Step 8

8

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

1.8 seconds

Go to Step 11

--

9
  1. Inspect the 1-2 shift circuit for the following conditions:
    2. • 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)
  2. Repair the 1-2 shift circuit.

Refer to Unit Repair.

Did you find and correct the condition?

--

Go to Step 12

--

10
  1. Inspect the 2-3 shift circuit for the following conditions:
    2. • 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
  2. Repair the 2-3 shift circuit.

Refer to Unit Repair.

Did you find and correct the condition?

--

Go to Step 12

--

11
  1. Inspect the 3-4 shift circuit for the following conditions:
    2. • 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
  2. Repair the 3-4 shift circuit.

Refer to Unit Repair.

Did you find and correct the condition?

--

Go to Step 12

--

12

Replace the torque converter.

Refer to Test Description 12 .

--

Go to Step 13

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13

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

  1. Select DTC.
  2. Select Clear Info.
  3. Operate the vehicle under the following conditions:
    4. • Drive the vehicle in D4 in order to obtain 1-2, 2-3, and 3-4 shifts.
    • Shift times must be less than 1.8 seconds.
    • Refer to Diagnostic Aid #2.
  4. Select Specific DTC. Enter DTC P1811.

Has the test run and passed?

--

System OK

Begin the diagnosis again. Go to Step 1