Hummer H1 Service Manual page 297

5-98 Transmission/Transfer Case
Stuck On:
• Commanded Gear equals 1st and ratio equals 3rd for
greater than 2 seconds (Actual gear equals 4th).
• Commanded Gear equals 2nd and ratio equals 3rd for
greater than 2 seconds.
• Conditions occur for 4 occurrences.
Stuck Off:
• Commanded Gear equals 3rd and ratio equals 1st for
greater than 3 seconds.
• Condition occurs for 8 occurrences (continual rolling
counter).
Action Taken When DTC Sets
• The transmission will immediately land to 2nd gear.
• The PCM will command maximum line pressure.
• The PCM will freeze shift adapts.
• The PCM will illuminate the warning lamp.
Conditions For Clearing DTC
• For California emission vehicles the PCM will turn the
lamp after three consecutive ignition cycles without a
failure reported.
• The DTC can be cleared by using the scan tool.
• The PCM will cancel the DTC default actions when the
fault no longer exists and the ignition is cycled "off'
long enough to power down the PCM.
Diagnostic Aids
• Verify that the transmission meets the specifications in
the 4L80-E shift speed chart.
• Other internal transmission failures may cause more
than one shift to occur.
• Customer may complain of an engine over-rev condi-
tion or neutral in 4th gear.
• If any engine DTCs or TP Sensor codes are present di-
agnose and clear these DTCs first. Then check to see if
the transmission DTCs have reset.
Test Description
The numbers below refer to the diagnostic chart.
2. This test checks the function of the PSA.
3. This test checks for selected gear ratio vs. a ratio not
obtainable under normal driving conditions.
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Gear
1
2
3
4
4L80-E CHART
1-2 Shift 2-3 Shift
Solenoid Solenoid
ON OFF
OFF OFF
OFF ON
ON ON
®