Content .. 75 76 77 78 ..

Hummer H1 (2002+). Manual - part 77

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Transmission/Transfer Case 5-107

05745159

After the repair is complete, use the scan tool to
select “DTC,” then “Clear in fold function.

Select “Specific DTC” and enter DTC “P1810.”

Operate the vehicle under the following condi-
tions:

• Turn the ignition switch “on” for at least 2 sec-

onds. Then start vehicle, idle for 5 seconds, then
drive vehicle in D4 until converter clutch locks
for 20 seconds.

—

Repair veri-

fied, exist

DTC table.

DTC P1810 Pressure Switch Circuit Fault (Cont’d)

Step

Action

Value

Yes

5-108

Transmission/Transfer Case

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DTC P1811 Maximum Adapt and Long Shift

Circuit Description

The Powertrain Control Module (PCM) compares the mea-
sured 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 inter-
val during which the gear ratio leaves the current range and
changes to reflect the commanded upshift. This interval is ex-
pressed on the scan tool as Shift Time. When this interval has
exceeded a predetermined limit, the PCM utilizes the shift
adapts 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 DTC

• The engine must be running for greater than 5 seconds.

• One of the following conditions exists, with the adapt

cells at the maximum pressure allowed for 5 consecu-
tive 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 6.38 seconds.

Action Taken When DTC Sets

• The PCM will default the transmission to maximum line

pressure.

• The PCM will freeze shift adapts.

Automatic
Transmission
Fluid
Pressure
Manual Valve
Position
Switch
(TFP)

Trans

Range C

Input

Trans

Range B

Input

Trans

Range A

Input

C34

Rev

Switch

C32-S

C32-H

C32-K

764 PP

763 DB

762 OR

C29-B4

C29-B5

C29-B6

A / T ISS

High

A / T ISS

Low

Tw i s t e d

P a i r

C32-A

Auto Trans Input Shaft

Speed Sensor

A/T ISS

C27-D1

C27-D11

495 DB

496 GY

POWERTRAIN
CONTROL
MODULE
(PCM)

FUSE 2A

10A

EXTERIOR

C33-F

351 PK

C34

C32-G

C32-F

C32-E

C32-D

C32-C

C32-J

C32-H

C34-E

C27-C15

C27-C7

C28-C5

C28-C6

C28-C4

C29-B12

C27-C9

265 LB

264 RD

924 TN

315 YL

237 LG

359 BK

923 BR

PRESSURE

CONTROL

SOLENOID

(PCS)

TORQUE

CONVERTER

CLUTCH

SOLENOID

(TCC)

1-2 SHIFT
SOLENOID
(1-2)

2-3 SHIFT
SOLENOID
(2-3)

TRANSMISSION

FLUID

TEMPERATURE

SENSOR

(TFT)

PCS

LOW

PCS

HIGH

TCC PWM

SOLENOID

CONTROL

2-3 SS

CONTROL

1-2 SS

CONTROL

SENSOR

GROUND

TFT

SENSOR

SIGNAL

POWERTRAIN

CONTROL

MODULE

(PCM)

HOT IN RUN
AND START

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Transmission/Transfer Case 5-109

05745159

Conditions For Clearing DTC

• The DTC can be cleared using the scan tool. The DTC

will be cleared from history when the vehicle has
achieved 40 warm-up cycles without reported failure.

• PCM will cancel DTC default actions when the fault no

longer exists and ignition is cycled “Off” long enough to
power down the PCM.

Diagnostic Aids

• Inspect wiring for poor electrical connections at the

PCM and the 20-way connector Look for possible bent,
backed out, deformed or damaged terminals. Also,
check for chafed wire that could short to bare metal or
other wiring. Inspect for broken wire inside the insula-
tion.

• When diagnosing a possible intermittent short or open

condition, move wiring while observing test equipment
for a reading change.

Test Description

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

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

3. This step compares the indicated range signal from the
Range Signal Chart to the Automatic Transmission Fluid Pres-
sure Manual Valve Position Switch (TFP Val. Position Sw.)
selected gear range.

5. This step tests for low line pressure, which can cause de-
layed and long shifts.

15. When DTC P1811 sets, the PCM commands maximum line
pressure and does not inhibit TCC engagement. High engine
speed and maximum line pressure can cause the Torque Con-
verter to “balloon”.

5-110

Transmission/Transfer Case

___________________________________________

DTC P1811 Maximum Adapt and Long Shift

Step

Action

Value

Yes

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

—

Go to

Step 2

Go to OBD

Powertrain

System Check.

Have you performed the transmission fluid checking procedure?

—

Go to

Step 3

Go to Transmis-

sion Fluid Check-

ing Procedure.

Install the scan tool.

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

Important

: Before clearing the DTC’s, use the scan tool in order

to record the Freeze Frame and Failure Records for reference.
The Clear Info function will erase the data.

Turn the ignition switch to the RUN position.

Record the DTC Freeze Frame Failure Records and DTC’s.
Use the scan tool snapshot mode in order to record the shift
times.

Important

: If any other engine or transmission DTC’s are set, re-

fer 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 7

Drive the vehicle in D4 in order to obtain a 1-2, a 2-3, and a
3-4 shift time.

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 above the specified value?

1-2, or 2-3

upshifts:

1.25 seconds

3-4 upshifts:

6.38 seconds

Go to

Step 5

Go to Step 8

Perform the line pressure test. Refer to Line Pressure Test.
Is the line pressure within specifications?

—

Go to

Step 6

Go to Symptom

Diagnosis Table,

Low Line Pressure

Remove the transmission oil pan. Refer to Transmission Oil
Pan Removal, in 4L80-E On-Vehicle Service.

Inspect the pan and the fluid for contamination.

Is there excessive contamination in the transmission oil pan?

—

Go to

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 Unit Repair.
Did you find and correct a problem?

—

Go to

Step 17

—

Inspect the 1-2, 2-3, and the 3-4 adapt cells on the scan tool.
Were any of the upshift adapt cells at their maximum adapt limit?

—

Go to

Step 9

Go to Diagnostic

Aids

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

6.38 seconds

Go to

Step 12

Go to Step 10

Content .. 75 76 77 78 ..