DTC P1811 Maximum Adapt and Long Shift. Cadillac Eldorado 1999

For 1990-2009 cars only

Makes 🢒 Cadillac 🢒 1999 🢒 Eldorado 🢒 Transmission/Transaxle 🢒 Automatic Transaxle - 4T80-E 🢒 DTC P1811 Maximum Adapt and Long Shift

Circuit Description

Important: Refer to the 1999 Transmission Unit Repair Manual (TURM) for Fluid Flow illustration.

An adaptive modifier modifies the transmission pressure. The adaptive modifier controls the shift execution time. This test checks the time required to accomplish the shift. If the shift takes longer than 0.55 seconds, 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.

Conditions for Running the DTC

•	No TP DTCs P0121, P0122, or P0123.

•	No Transmission Fluid Overtemperature DTC P0218.

•	No VSS DTCs P0502 or P0503.

•	No TFT DTCs P0711, P0712, or P0713.

•	The transmission fluid temperature is greater than 50°C (122°F).

•	The vehicle speed is greater than 16 km/h (10 mph).

•	The throttle angle is greater than 15.7 degrees.

Conditions for Setting the DTC

One of the following cases occurs:

Case 1

•	The 1-2 shift is longer than 0.55 seconds.

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

Case 2

•	The 2-3 shift is longer than 0.55 seconds.

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

Case 3

•	The 3-4 shift is longer than 0.55 seconds.

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

Action Taken When the DTC Sets

•	The PCM does not illuminate the malfunction indicator lamp (MIL).

•	SERVICE VEHICLE SOON, SERVICE TRANSMISSION displays on the driver information center (DIC).

•	The PCM commands maximum line pressure.

•	The PCM freezes steady state adapts.

•	The PCM freezes upshift adapts.

•	The PCM freezes garage shift adapts.

•	The PCM stores DTC P1811 in PCM history.

Conditions for Clearing the DIC/DTC

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

•	Shift times are less than 0.55 seconds for three occurrences.

•	A scan tool can clear the DTC from PCM history.

•	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 fault no longer exists and the ignition switch is OFF long enough in order to power down the PCM.

Diagnostic Aids

•	Ensure that the PCM has the latest update.

•	If a transmission overhaul was performed, use the scan tool to clear all adapts.

Test Description

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

This step reviews the 1-2 adapt cell along with shift time. If the pressure readings match or exceed the parameters listed in the value column, then the PCM modifies the base line pressure on a 1-2 shift. This modification adjusts the holding effect of a clutch or band.

This step reviews the 2-3 adapt cell along with shift time. If pressure readings match or exceed the parameters listed in the value column, then the PCM 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 cell along with shift time. If pressure readings match or exceed the parameters listed in the value column, then the PCM 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 gauge readings do not match the commanded PC solenoid valve current to line pressure located in the value column.

DTC P1811 Maximum Adapt and Long Shift

Step

Action

Value(s)

Yes

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

Go to Step 2

Go to Powertrain On Board Diagnostic (OBD) System Check

Was the Transmission Fluid Checking Procedure performed?

Go to Step 3

Go to Transmission Fluid Check

Install the Scan Tool .
Turn the ignition switch to the RUN position.

Important: Before clearing the DTCs, use the scan tool in order to record the Failure Records. Using the Clear Info function erases the Failure Records from the PCM.

Record the Failure Records.
Clear the DTCs.

Are any of the following DTCs set: P0120, P0121, P0122, P0123, P0218, P0502, P0503, P0711, P0712, P0713, P1121, P1122, or P1524?

Go to Step 4

Go to Step 5

Diagnose the DTCs found in step 3 first.

Is the diagnosis and repair complete?

Go to Step 16

Select Transmission Adapts on the scan tool.
Scan through the data lists and review the following parameters:

•	1-2 TAP Low

•	1-2 TAP High

•	1-2 Shift Time

Is the scan tool display equal to or greater than the specified parameters?

1-2 TAP Low -30 or +30 PSI

1-2 TAP High -30 or +30 PSI

1-2 Shift Time 0.55 sec

Go to Step 8

Go to Step 6

Review the following parameters:

•	2-3 TAP Low,

•	2-3 TAP High

•	2-3 Shift Time

Is the scan tool display equal to or greater than the specified parameters?

2-3 TAP Low -30 or +30 PSI

2-3 TAP High -30 or +30 PSI

2-3 Shift Time 0.55 sec

Go to Step 9

Go to Step 7

Review the following parameters:

•	3-4 TAP Low

•	3-4 TAP High

•	3-4 Shift Time

Is the scan tool display equal to or greater than the specified parameters?

3-4 TAP Low -30 or +30 PSI

3-4 TAP High -30 or +30 PSI

3-4 Shift Time 0.55 sec

Go to Step 10

Go to Step 11

Inspect the following items:

The line pressure is too low.
The pressure control solenoid is stuck ON.
The pressure control solenoid has a broken clamp causing leakage.
The clutch plates (431 through 435) are burned or damaged.
The piston assembly 2nd clutch is cracked or damaged.
The 2nd clutch return spring and retainer assembly are broken or out of position.
The 2nd clutch piston assembly seals are rolled, damaged or leaking.
The 2nd sprag clutch assembly is damaged or not holding.
The 1-2 shift solenoid valve is stuck ON.
The 1-2 shift valves (A & B) are stuck in 1st gear.

Repair any of the above items as necessary.

Refer to Unit Repair.

Is the repair complete?

Go to Step 16

Inspect the following items:

•	Line pressure is too low.

•	The pressure control solenoid is stuck ON.

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

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

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

•	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.

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

Repair any of the above items as necessary.

Refer to Unit Repair.

Is the repair complete?

Go to Step 16

Inspect the following items:

The line pressure is too low.
The pressure control solenoid is stuck ON.
The pressure control solenoid clamp is broken, causing leakage.
The 4th band is burned, slipping or missing.
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.
The 3-4 shift valve bore plug is mis-assembled.

Repair any of the above items as necessary.

Refer to Unit Repair.

Is the repair complete?

Go to Step 16

Install the J 21867 pressure gauge 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 gauge.

Does the scan tool display match the specified pressure gauge 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 12

Is the line pressure high?

Go to Step 14

Go to Step 13

Is the line pressure low?

Go to Step 15

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 control solenoid feed valve is stuck

•	The pressure regulator boost valve is stuck open

•	Ball check valve (65) is missing

•	The final drive internal gear snap ring is missing

•	The actuator feed limit valve is stuck open

Repair any of the above items as necessary.

Refer to Unit Repair.

Is the repair complete?

Go to Step 16

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

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

•	The scavenge screens (51 and 52) are clogged

•	The pressure regulator valve is stuck due to sediment

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

•	The transmission fluid level is low

•	The cooler lines are clogged or restricted.

Repair any of the above items as necessary.

Refer to Unit Repair.

Is the repair complete?

Go to Step 16

Perform the following procedure in order to verify the repair:

Select DTC.
Select Clear Info.
Select Reset Adapts.
Operate the vehicle under the following conditions:

•	Road test the vehicle with the gear select lever in D4.

•	Ensure that the following conditions are met:

-	The transmission temperature is greater than 50°C.

-	The TP angle greater than 15.7 degrees.

-	The vehicle speed is greater than 16 km/h (10 mph).

•	The vehicle must achieve a 1-2, 2-3 and 3-4 upshift within 0.55 seconds three consecutive times.

Select Specific DTC. Enter DTC P1811.

Has the test run and passed?

System OK

Go to Step 1