DTC P1811 Maximum Adapt and Long Shift. GMC Truck Savana 1998

For 1990-2009 cars only

Makes 🢒 GMC_Truck 🢒 1998 🢒 Savana 🢒 DTC 🢒 DTC P1811 Maximum Adapt and Long Shift

DTC P1811 Maximum Adapt and Long Shift Diesel Only

Table 1:	4L80-E Range Reference, modified for DTCs P1870 & P1871
Table 2:	DTC P1811 Maximum Adapt-Long Shift Time

4L80-E Range Reference, modified for DTCs P1870 & P1871

Range	Gear	1-2 Sol	2-3 Sol	Fourth Clutch	Overrun Clutch	O/D Roller Clutch	FWD Clutch	Direct Clutch	Front Band	Interm. Sprag Clutch	Interm Clutch	Lo Roller Clutch	Rear Band
Overdrive	1st	On	Off	--	--	H	A	--	--	*	--	H	--
	2nd	Off	Off	--	--	H	A	--	--	H	A	O	--
	3rd	Off	On	--	--	H	A	A	--	O	A	O	--
	4th	On	On	A	--	O	A	A	--	O	A	O	--
A = Applied H = Holding * = Holding but not effective O = Overrunning

Circuit Description

The Powertrain Control Module (PCM) compares the measured gear ratio to the known actual value. This allows the PCM to determine the actual gear range of the transmission. When an upshift is commanded, the PCM measures the interval during which the gear ratio leaves the current range and changes to reflect the commanded upshift. This interval is expressed on the scan tool as Shift Time. When this interval has exceeded a predetermined limit, the PCM utilizes the shift adapts in order to attempt to shorten the shift time.

If the PCM detects that the maximum allowable shift time has been exceeded, and that the upshift adapts have reached their upper limit, then DTC P1811 sets. DTC P1811 is a type D DTC.

Conditions for Setting the DTC

•	The engine must be running at greater than 475 RPM for more than 7 seconds.

•	One of the following conditions exists, with the adapt cells at the maximum pressure allowed for 5 consecutive occurrences of one shift.

-	The 1-2 or the 2-3 upshifts are greater than 1.25 seconds.

-	The 3-4 upshifts are greater than 6.37 seconds.

Action Taken When the DTC Sets

•	The PCM does not illuminate the Malfunction Indicator Lamp (MIL).

•	The PCM freezes shift adapts.

•	The PCM commands maximum line pressure.

•	DTC P1811 is stored in 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

•	DTC P1811 can be caused by a faulty turbocharger or wastegate assembly. If no other symptoms are present, check the turbocharger system for proper operation.

•	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.

•	While driving the vehicle, inspect for loss of power, misfire, or other engine-related driving problems.

Test Description

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

This step compares the indicated range signal from the Range Signal table to the Automatic Transmission Fluid Pressure Manual Valve Position Switch (TFP Val. Position Sw.) selected gear range.

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

DTC P1811 Maximum Adapt-Long Shift Time

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

Perform the Transmission Fluid Checking Procedure.

Refer to Transmission Fluid Check .

Have you performed the transmission fluid checking procedure?

Go to Step 3

Go to Transmission Fluid Check

Install the Scan Tool .
With the engine OFF, turn the ignition switch to the RUN position.

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

Record the DTC Freeze Frame, then clear the DTC.

Important: If any other engine or transmission DTCs are set, refer to their respective diagnostic tables first.

Select TFP Sw. A/B/C on the scan tool.
Start the engine and apply the brake pedal.
Select each gear range: D1, D2, D3, D4, N, R, and P.

Does each selected transmission range match the TFP Sw. A/B/C display on the scan tool? (Refer to the Range Signal table.)

Go to Step 4

Go to DTC P1810 TFP Valve Position Switch Circuit

Drive the vehicle in D4 in order to obtain a 1-2, a 2-3, and a 3-4 shift time. Use the scan tool snapshot mode in order to record the shift times.
Using the scan tool, review the shift time information for 1-2, 2-3, and 3-4 shift times.

Were all of the shift times greater than the specified value?

1-2 or 2-3 upshifts: 1.25 seconds

3-4 upshifts: 6.37 seconds.

Go to Step 5

Go to Step 8

Perform the line pressure test.

Refer to Line Pressure Check .

Is the line pressure within specifications?

Go to Step 6

Go to Low Line Pressure

Remove the transmission oil pan.

Refer to Automatic Transmission Fluid and Filter Replacement .

Inspect the pan and the fluid for contamination.

Is there excessive contamination in the transmission oil pan?

Go to Transmission Overhaul Procedure, in Unit Repair.

Go to Step 7

Inspect the transmission for fluid pressure loss in one of the following areas:

•	Valve Body Gasket

•	Forward Clutch Seals

•	Turbine Shaft Seals

Refer to Transmission Overhaul Procedure, in Unit Repair.

Did you find and correct the condition?

Go to Step 15

Select the 1-2, 2-3, and the 3-4 Transmission Adaptive Pressure (TAP) cells on the scan tool.

Were any of the upshift TAP cells greater than the specified value?

16.0 psi

Go to Step 9

Go to Diagnostic Aids

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

6.37 seconds

Go to Step 12

Go to Step 10

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

1.25 seconds

Go to Step 13

Go to Step 11

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

1.25 seconds

Go to Step 14

Inspect the following 3-4 shift circuit components:

•	4th Gear Clutch Plates

•	4th Gear Clutch Seals

•	A sticking 3-4 Shift Valve.

Refer to Transmission Overhaul Procedure, in Unit Repair.

Did you find and correct the condition?

Go to Step 15

Inspect the following 2-3 shift circuit components:

•	Turbine Shaft Seals

•	Forward Clutch Plates

•	Forward Clutch Seals

•	Direct Clutch Plates

•	Direct Clutch Seals

•	Center Support Seals

•	Improperly tightened Center Support Bolt

Refer to Transmission Overhaul Procedure, in Unit Repair.

Did you find and correct the condition?

Go to Step 15

Inspect the following 1-2 shift circuit components:

•	Low Roller Clutch

•	Intermediate Clutch Plates

•	Intermediate Clutch Seals

•	Intermediate Sprag Clutch

•	Overdrive Roller Clutch

•	Improperly tightened Center Support Bolt

Refer to Transmission Overhaul Procedure, in Unit Repair.

Did you find and correct the condition?

Go to Step 15

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

Select DTC.
Select Clear Info.
Drive the vehicle in D4 range.
Operate the vehicle through several 1,2,3,4 usphifts.
Review the scan tool 1-2, 2-3 and 3-4 shift times.

Are the 1-2, 2-3, or 3-4 shift times less than the specified value?

1-2 and 2-3 upshifts 1.25 seconds 3-4 upshifts 6.37 seconds

System OK

Begin the diagnosis again. Go to Step 1