GM Service Manual Online
For 1990-2009 cars only
Makes 🢒 Chevrolet 🢒 2005 🢒 Cobalt 🢒 Restraints 🢒 SIR 🢒 DTC P1811

Object Number: 40585 Size: MF

Circuit Description

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

When the TCM 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 shift adapt is at the 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 TCM does not illuminate the malfunction indicator lamp (MIL).
    • The TCM commands maximum line pressure.
    • The TCM freezes transmission adaptive functions.
    • The TCM records the operating conditions when the Conditions for Setting the DTC are met. The TCM stores this information as Failure Records.
    • The TCM stores DTC P1811 in TCM history.

Conditions for Clearing the DTC
    • A scan tool can clear the DTC.
    • The TCM clears the DTC from TCM history if the vehicle completes 40 warm-up cycles without a non-emission related diagnostic fault occurring.
    • The TCM cancels the DTC default actions when the fault no longer exists and the DTC passes.

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.

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

    2.

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

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 in Vehicle DTC Information

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 DTC, use the scan tool in order to record the Failure Records. Using the Clear Info function erases the Failure Records from the TCM.

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

Did all the shift times exceed the specified value?

0.65 second

Go to Step 4

Go to Step 6

4

Did you perform the Line Pressure Check Procedure?

--

Go to Step 5

Go to Line Pressure Check

5
  1. Inspect the transmission for the following conditions:
    2. • Low fluid level caused by external leaks
    • Internal fluid passage leaks
    • Casting porosity or damage
    • Refer to Case Inspection in Unit Repair.
    • Clogged fluid filter
    • Out-of-position fluid filter
    • 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
    • Refer to Control Valve Body Disassemble in Unit Repair.
    • Leaking oil pump
    • Damaged oil pump
    • Inadequate oil pump suction
    • Oil pump cavitation
    • Refer to Oil Pump Cleaning and Inspection in Unit Repair.
  2. Repair any of the above conditions as necessary.

Did you complete the repair?

--

Go to Step 12

--

6

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

0.65 second

Go to Step 9

Go to Step 7

7

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

0.65 second

Go to Step 10

Go to Step 8

8

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

0.65 second

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
    • Refer to Channel Plate Assembly Disassemble in Unit Repair.
    • 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
    • Cracked or damaged driven sprocket support
    • Leaking driven sprocket support seals
    • Damaged driven sprocket support seals
    • Refer to Driven Sprocket Support Assembly Disassemble in Unit Repair.
    • Internal fluid passage leaks
    • Casting porosity or damage
    • Refer to Case Inspection in Unit Repair.
    • Damaged gasket or spacer plate
    • Out-of-position gasket or spacer plate
    • Refer to Control Valve Body Disassemble in Unit Repair.
    • Slipping forward clutch
    • Damaged sprag clutch, not holding
    • 2nd roller clutch damaged, not holding
  2. Repair the 1-2 shift circuit as necessary.

Did you complete the repair?

--

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
    • Refer to Channel Plate Assembly Disassemble in Unit Repair.
    • 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
    • Damaged, or not holding, sprag clutch
    • Leaking driven sprocket support seals
    • Damaged driven sprocket support seals
    • Damaged driven sprocket support
    • Refer to Driven Sprocket Support Assembly Disassemble in Unit Repair.
    • Internal fluid passage leaks
    • Casting porosity or damage
    • Refer to Case Inspection in Unit Repair.
    • Damaged gasket or spacer plate
    • Out-of-position gasket or spacer plate
    • Refer to Control Valve Body Disassemble in Unit Repair.
  2. Repair the 2-3 shift circuit as necessary.

Did you complete the repair?

--

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
    • Refer to Channel Plate Assembly Disassemble in Unit Repair.
    • Leaking intermediate/4th servo piston seals
    • Rolled intermediate/4th servo piston seals
    • Cut intermediate/4th servo piston seals
    • 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
    • Refer to Intermediate/Fourth Servo Disassemble in Unit Repair.
    • Burned intermediate/4th band
    • Out-of-position intermediate/4th band
    • Damaged intermediate/4th band
    • Slipping intermediate/4th band
    • Refer to Intermediate Fourth Band Removal in Unit Repair.
    • Internal fluid passage leaks
    • Casting porosity or damage
    • Refer to Case Inspection in Unit Repair.
    • Damaged gasket or spacer plate
    • Out-of-position gasket or spacer plate
    • Refer to Control Valve Body Disassemble in Unit Repair.
    • Slipping direct clutch
  2. Repair the 3-4 shift circuit as necessary.

Did you complete the repair?

--

Go to Step 12

--

12
  1. Change the AT fluid and filter.

    2. Refer to Automatic Transmission Fluid Filter and Seal Replacement .

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

Did you complete the above procedures?

--

Go to Step 13

--

13

Perform the following procedure in order to verify the repair:

  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 0.65 second.
  4. Select Specific DTC.
  5. Enter DTC P1811.

Has the test run and passed?

--

Go to Step 14

Go to Step 2

14

With the 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 in Vehicle DTC Information

System OK