DTC P1811. Buick Lucerne 2006

For 1990-2009 cars only

Makes 🢒 Buick 🢒 2006 🢒 Lucerne 🢒 Vehicle Control Systems 🢒 Computer/Integrating Systems 🢒 DTC P1811

Circuit Description

Important: Refer to the 2006 Transmission Unit Repair Manual (TURM) for Fluid Flow illustration.

An adaptive modifier modifies the transmission line pressure. The adaptive modifier controls the shift execution time. This DTC monitors 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 iterates.

DTC P1811 sets when this counter reaches its limit. 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

An adaptable shift has occurred.

Conditions for Setting the DTC

One of the following conditions occurs twice during the same trip:

Condition 1

•	The 1-2 shift is longer than 0.65 second.

•	The 1-2 shift adapt has reached its limit.

Condition 2

•	The 2-3 shift is longer than 0.65 second.

•	The 2-3 shift adapt has reached its limit.

Condition 3

•	The 3-4 shift is longer than 0.65 second.

•	The 3-4 shift adapt has reached its limit.

Action Taken When the DTC Sets

•	The TCM does not request the engine control module (ECM) to 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 DIC/DTC

•	The TCM clears the DIC message when the condition no longer exists.

•	A scan tool can clear the DIC/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.

•	Ensure that the TCM has the latest calibration update.

Test Description

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

This step reviews the 1-2 adapt cells. If the pressure readings match or exceed the value listed in the value column, then the TCM modifies the base line pressure on a 1-2 shift. This modification adjusts the holding effort of a clutch or band.

This step reviews the 2-3 adapt cells. If pressure readings match or exceed the value listed in the value column, then the TCM modifies the base line pressure on a 2-3 shift. This modification adjusts the holding effort of a clutch or band.

This step reviews the 3-4 adapt cells. If pressure readings match or exceed the values listed in the value column, then the TCM modifies the base line pressure on a 3-4 shift. This modification adjusts the holding effort of a clutch or band.

This step inspects or repairs any of the components listed. A faulty component may lead to a maximum adapt and long shift during a 1-2 upshift.

This step inspects or repairs any of the components listed. A faulty component may lead to a maximum adapt and long shift during a 2-3 upshift.

This step inspects or repairs any of the components listed. A faulty component may lead to a maximum adapt and long shift during a 3-4 upshift.

This step inspects components located within the valve body, if the fluid pressure gage readings do not match the commanded PC solenoid valve current to line pressure located in the value column.

DTC P1811

Step

Action

Values

Yes

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

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 TCM.

Record the DTC Failure Records.
Clear the DTC.
Select Transmission Adapts/1-2 Adapt. Data on the scan tool.
Review the 1-2 TAP cells 4-16.

Do any cells display a value equal to or greater than the specified value?

184.48 kPa

(26.75 psi)

Go to Step 6

Go to Step 4

Select Transmission Adapts/2-3 Adapt. Data on the scan tool.
Review the 2-3 TAP cells 4-16.

Do any cells display a value equal to or greater than the specified value?

184.48 kPa

(26.75 psi)

Go to Step 7

Go to Step 5

Select Transmission Adapts/3-4 Adapt. Data on the scan tool.
Review the 3-4 TAP cells 4-16.

Do any cells display a value equal to or greater than the specified value?

184.48 kPa

(26.75 psi)

Go to Step 8

Go to Step 9

Inspect the following items:

•	The line pressure is too low.

•	Refer to Line Pressure .

•	The pressure control solenoid valve is stuck ON.

•	The pressure control solenoid valve has a broken clamp causing leakage.

•	The 1-2 shift solenoid valve is stuck ON.

•	The 1-2 shift valves (A & B) are stuck in 1st gear.

•	Refer to Control Valve Upper Body Disassemble in the 4T80-E section of the Transmission Unit Repair Manual.

•	The clutch plates (431 through 435) are burned or damaged.

•	Refer to Clutch Plate Diagnosis .

•	The 2nd clutch piston assembly is cracked or damaged.

•	The 2nd clutch return spring and retainer assembly is damaged or out of position.

•	The 2nd clutch piston assembly seals are rolled, damaged or leaking.

•	Refer to Second Clutch Plates and Reverse Clutch Removal in the 4T80-E section of the Transmission Unit Repair Manual.

•	The 2nd sprag clutch assembly is damaged or not holding.

•	Refer to Reverse Clutch Housing and Second Sprag Disassemble in the 4T80-E section of the Transmission Unit Repair Manual.

Repair any of the above items as necessary.

Is the repair complete?

Go to Step 14

Inspect the following items:

•	Line pressure is too low.

•	Refer to Line Pressure .

•	The pressure control solenoid valve is stuck ON.

•	The pressure control solenoid valve has a broken clamp causing leakage.

•	Refer to Control Valve Upper Body Disassemble in the 4T80-E section of the Transmission Unit Repair Manual.

•	The 3-4 shift solenoid valve bore plug is mis-assembled.

•	Refer to Control Valve Lower Body Disassemble in the 4T80-E section of the Transmission Unit Repair Manual.

•	The 3rd clutch exhaust valve cup plug or the exhaust valve are installed improperly in the driven sprocket support.

•	Refer to Driven Sprocket Support Disassemble in the 4T80-E section of the Transmission Unit Repair Manual.

•	The ball check valve (437) is stuck or missing.

•	The 3rd clutch plates are burned or the spline is damaged.

•	The 3rd clutch piston is cracked or damaged, or the checkball is damaged.

•	The 3rd clutch piston seals are cut or rolled.

•	Refer to 3rd Clutch Plate Assembly and Reaction Carrier Disassemble in the 4T80-E section of the Transmission Unit Repair Manual.

Repair any of the above items as necessary.

Is the repair complete?

Go to Step 14

Inspect the following items:

•	The line pressure is too low.

•	Line Pressure .

•	The pressure control solenoid valve is stuck ON.

•	The pressure control solenoid valve clamp is broken, causing leakage.

•	Refer to Control Valve Upper Body Disassemble in the 4T80-E section of the Transmission Unit Repair Manual.

•	The 4th band is burned, slipping or missing.

•	Refer to 4th Band and Third Clutch/Reaction Shell Removal in the 4T80-E section of the Transmission Unit Repair Manual.

•	The 4th servo piston is damaged.

•	The 4th servo pin is broken or seized.

•	The 4th servo seals are rolled, cut or damaged.

•	The 4th servo cover is cracked.

•	Refer to Fourth Servo Overhaul in the 4T80-E section of the Transmission Unit Repair Manual.

•	The 3-4 shift valve bore plug is mis-assembled.

•	Refer to Control Valve Lower Body Disassemble in the 4T80-E section of the Transmission Unit Repair Manual.

Repair any of the above items as necessary.

Is the repair complete?

Go to Step 14

Install the J 21867 Pressure Gage and J 21867-94 Line Pressure Fitting.
Start the engine.
Using the scan tool command the PC solenoid valve current high, then command the PC solenoid valve current low and observe the pressure gage.

Does the scan tool display match the specified pressure gage parameters?

0.10 A = 240-260 psi

0.20 A = 210-250 psi

0.30 A = 190-240 psi

0.40 A = 175-210 psi

0.50 A = 150-200 psi

0.60 A = 125-175 psi

0.70 A = 110-160 psi

0.80 A = 80-130 psi

0.90 A = 75-125 psi

Go to Diagnostic Aids

Go to Step 10

Is the line pressure high?

Go to Step 12

Go to Step 11

Is the line pressure low?

Go to Step 13

Inspect the following components for high line pressure:

•	The pressure regulator valve is stuck at a high torque signal due to an undersized bore or sediment.

•	The pressure regulator boost valve is stuck open.

•	The pressure control solenoid feed valve is stuck.

•	Refer to Secondary Pump Disassemble in the 4T80-E section of the Transmission Unit Repair Manual.

•	The actuator feed limit valve is stuck open.

•	Refer to Control Valve Upper Body Disassemble in the 4T80-E section of the Transmission Unit Repair Manual.

•	Ball check valve (65) is missing.

•	Refer to Oil Pump, Upper Control Valve Assembly Removal in the 4T80-E section of the Transmission Unit Repair Manual.

•	The final drive internal gear snap ring is missing.

•	Refer to Final Drive Carrier Inspect in the 4T80-E section of the Transmission Unit Repair Manual.

Repair any of the above items as necessary.

Is the repair complete?

Go to Step 14

Inspect the following components for low line pressure:

•	The scavenge pump body is leaking at the gasket or the pump body.

•	The scavenge pipe is restricted.

•	The scavenge pipe seal is cut or leaking.

•	Refer to Case Extension and Scavenge Pipe Removal in the 4T80-E section of the Transmission Unit Repair Manual.

•	The primary pump body is leaking at the gasket or the pump body.

•	Refer to Oil Pump, Upper Control Valve Assembly Removal in the 4T80-E section of the Transmission Unit Repair Manual.

•	The scavenge screens (51 and 52) are clogged.

•	Refer to Transfer Oil Pump Inlet Screen and Pipe Seal Replacement in the 4T80-E section of the Transmission Unit Repair Manual.

•	The pressure regulator valve is stuck due to sediment.

•	The secondary pump body is leaking at the gasket or the pump body.

•	Refer to Secondary Pump Disassemble in the 4T80-E section of the Transmission Unit Repair Manual.

•	The transmission fluid level is low.

•	Refer to Transmission Fluid Check .

•	The cooler lines are clogged or restricted.

•	Refer to Transmission Fluid Cooler Flushing and Flow Test .

Repair any of the above items as necessary.

Is the repair complete?

Go to Step 14

Change the AT fluid and filter.

Refer to Auxiliary Control Valve Body Cover, Fluid Filter Seal, and Filter Removal in the 4T80-E section of the Transmission Unit Repair Manual.

Inspect the AT 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 TCM will update the adapt cell values as the vehicle is driven.

Use the scan tool in order to perform the following:

•	Reset oil life monitor to 100%.

•	Clear TAPS.

Did you complete the repair?

Go to Step 15

Perform the following procedure in order to verify the repair:

Select Special Functions.
Select Transmission Output Controls.
Select Clear TAP.
Operate the vehicle under the following conditions:

•	Drive the vehicle in D4 in order to obtain 1-2, 2-3, 3-4 shifts.

•	Shift times must be less than 0.65 second.

Select Specific DTC.
Enter DTC P1811.

Has the test run and passed?

Go to Step 16

Go to Step 2

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

System OK