Hummer H1 Service Manual page 309

5-110 Transmission/Transfer Case
Step
1 Was the Powertrain ON-Board Diagnostic (OBD)
System Check performed?
2 Have you performed the transmission fluid checking procedure?
3 1. Install the scan tool.
2. 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.
3. Turn the ignition switch to the RUN position.
4. 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.
5. Select TFP sw. A/B/C on the scan tool.
6. Start the engine and apply the brake pedal.
7. 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.
4 1. Drive the vehicle in D4 in order to obtain a 1-2, a 2-3, and a
3-4 shift time.
2. 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?
5 Perform the line pressure test. Refer to Line Pressure Test.
Is the line pressure within specifications?
6 1. Remove the transmission oil pan. Refer to Transmission Oil
Pan Removal, in 4L80-E On-Vehicle Service.
2. Inspect the pan and the fluid for contamination.
Is there excessive contamination in the transmission oil pan?
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?
8 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?
9 Did the 3-4 shift time exceed the specified value?
___________________________________________
DTC P1811 Maximum Adapt and Long Shift
Action Value Yes
— Go to
Step 2
— Go to
Step 3
—
Go to
Step 7
1-2, or 2-3
upshifts:
1.25 seconds
3-4 upshifts:
Go to
6.38 seconds
Step 5
— Go to
Step 6
Go to
—
Unit
Repair
—
Go to
Step 17
Go to
—
Step 9
Go to
6.38 seconds
Step 12
®
No
Go to OBD
Powertrain
System Check.
Go to Transmis-
sion Fluid Check-
ing Procedure.
Go to Step 8
Go to Symptom
Diagnosis Table,
Low Line Pressure
Go to Step 7
—
Go to Diagnostic
Aids
Go to Step 10