Hummer H1 Service Manual page 269

5-70 Transmission/Transfer Case
Conditions for Clearing the DTC
1. The PCM turns OFF the MIL after three consecutive igni-
tion cycles without a failure reported.
2. 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.
3. 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
• Inspect the wiring for poor electrical connections at the
PCM. Inspect the wiring for poor electrical connections at
the transmission 20-way connector. Look for the following
problems:
• A bent terminal
• A backed out terminal
• A damaged Terminal
• Poor terminal tension
• A chafed wire
• A broken wire inside the insulation
Step
1
Was the Powertrain On-Board Diagnostic (OBD) Sys-
tem Check Performed
2 1. Install the scan tool (Tech 1)
2. 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. The Clear
Info function will erase the data.
3. Record the DTC Freeze Frame and Failure Records
and DTCs.
4. Raise the drive wheels and support the axle assem-
bly.
5. Start the engine and place the transmission in Drive
3 range.
6. Gradually increase the wheel speed.
Does the Transmission OSS increase with the drive
wheel speed?
_____________________________________________
DTC P0722 Output Speed Sensor Low Input
Action
• When diagnosing for an intermittent short or open, mas-
sage the wiring harness while watching the test equipment
for a change. It may be necessary to drive the vehicle.
• Inspect the Speed Sensor wiring for contact with sharp
metal edges.
Test Description
The numbers below refer to the step numbers on the diagnostic
table.
2. This step verifies the fault condition.
3. This step tests OSS Sensor integrity.
9. This step verifies power and ground to the VSS Buffer
Module.
15.This step verifies the PCM input controlled by the
Speed Buffer.
Value
—
—
Yes No
Go to Power-
train OBD
Go to Step 2 System Check
Cannot verify
faulty. Exit
DTC table and
go to Diagnos-
tic Aids Go to Step 3
®