Hummer H1 Service Manual page 1143

78 PCM/Tech 1 Scan Tool
DTC P0263, P0266, P0269, P0272, P0275, P0278, P0281 and P0284
Cylinder Balance System Faults
Step
1 Important: Before clearing DTC(s) use the scan tool "Capture Info" to
record freeze frame and failure records for reference, as data will be lost
when "Clear Info" function is used.
Was the "On-Board Diagnostic (OBD) System Check" performed?
2 1. Scan tool connected.
2. Start and idle engine.
3. Engine at operating temperature.
4. Make sure all DTCs are cleared.
5. Using the scan tool, cutout ("Inj. Balance") the suspected cylinder.
Is there an RPM drop in the suspected cylinder?
3 DTC is intermittent. If no additional DTCs are stored, refer to "Diagnostic
Aids". If additional DTCs are stored, refer to those table(s).
Are additional DTCs stored?
4 Check for a basic engine mechanical or fuel delivery problem in that cylin-
der.
Was a repair performed?
5 Replace the fuel injection pump. Refer to Fuel Injection Pump .
Is the action complete?
6 1. Using the Scan Tool, select "DTC", "Clear Info".
2. Start engine and idle at normal operating temperature.
3. Select "DTC", "Specific", then enter the DTC number which was set.
4. Operate vehicle within the conditions for setting this DTC as specified in
the supporting text.
Does the Scan Tool indicate that this diagnostic Ran and Passed?
7 Using the Scan Tool, select "Capture Info", "Review Info".
Are any DTCs displayed that have not been diagnosed?
_____________________________________________________
Action Value(s) Yes
— Go to Step 2.
— Go to Step 3. Go to Step 4.
— Go to the
applicable
DTC table.
— Go to Step 6.
— Go to Step 6.
— Go to Step 7.
— Go to the
applicable
DTC table
®
No
Go to OBD
System Check.
Go to
Diagnostic
Aids.
Go to Step 5.
—
Go to Step 2.
System OK.