Hummer H1 Service Manual page 249

5-50 Transmission/Transfer Case
.
Step
1 Was the Powertrain On-Board Diagnostic (OBD)
System Check performed?
2 Install the scan tool.
WIth the engine off, turn the ignition switch to the
run positon.
Impotant: Before clearing the DTCs, use the
scan tool to record teh Freeze Frame and Failure
Records for reference. Using the Clear Info func-
tion erases the stored Failure Records from the
PCM.
Record the DTC Failure Records then clear the
DTC.
Perform the Transmission Fluid Checking Proce-
dure.
Was the Transmission Fluid Checking Proceedure
performed?
3 Is DTC P0711 also set?
4 Inspect the cooling system for the following con-
ditions:
• Air flow restrictions
• Air flow blockage
Inspect the transmission cooling system for the
following conditions:
• Air flow restrictions
• Air flow blockage
• Damaged cooler lines or hoses
• Low A/T fluid cooler flow. Refer to A/T cooler
flow test.
Was the condition found?
5 Perform the line pressure check procedure. Refer
to 4L80-E Line Pressure Check Procedure.
Was the condition found?
6 Inspect the torque converter stator for damage.
Refer to Torque Converter Clutch Diagnosis.
Was the condition found?
7 In order to verify your repair, perform the follow-
ing procedure:
1. Select DTC.
2. Select Clear Info.
3. Operate the vehicle under the following con-
ditons.
• Turn the ignition switch to the RUN position.
• The TFT must be less than 129°C (264°F) for at
least 5 seconds.
4. Select Specific DTC. Enter P0218.
5. Has the test run and passed?
_____________________________________________
DTC P0218 Transmission Fluid Overtemperature
Action Value(s) Yes
Go to step 2
Go to step 3
Go to diagnostic
aids
Go to step 7
Go to step 7
Go to step 7
System OK
®
No
Go to Power-
train OBD Sys-
tem Check
Go to transmis-
sion fluid check-
ing procedure
Go to step 4
Go to step 5
Go to step 6
Go to system
diagnosis table
"Transmission
Overheating"
Begin the diag-
nosis again. Go
to step 1