Hummer H1 Service Manual page 811

12-40 Electrical System
Step
1 Before clearing any DTC's, use the scan tool Cap-
ture Info to save the Freeze Frame and Failure
Records for reference. The PCM's data is deleted
once the Clear Info function is used.
Did you perform the On-Board Diagnostic (OBD)
System Check?
2 If DTC P0380 is set after a PCM reflash.
Connect a scan tool. Turn the ignition ON leaving
the engine OFF. Observe the Glow Plug System
Type parameter on the scan tool.
Does the scan tool display the Glow Plug System
Type as California?
3 Connect a scan tool. Turn the ignition ON leaving
the engine OFF. Use the scan tool to command
the glow plugs ON and OFF. Observe the Glow
Plug System Type parameter on the scan tool.
Does the digital multimeter (DMM) display a
voltage near the first specified value with the glow
plug commanded ON and near the second speci-
fied value with the glow plug commanded OFF?
4 Does the scan tool display a glow plug voltage
greater than the specified value?
5 Does the scan tool display a glow plug voltage
greater than the specified value?
6 Turn the ignition ON leaving the engine OFF.
Touch the battery feed stud on the glow plug con-
troller with an unpowered test lamp connected to
ground.
Is the test light ON?
7 The DTC is intermittent. If any additional DTC's
were stored, refer to those table(s).
Were there any additional DTC's stored?
8 Disconnect the glow plug relay control connector.
Turn the ignition ON with the engine OFF. With
an unpowered test lamp connected to ground,
probe the glow plug relay harness ignition feed
circuit (CKT 239 PK).
Is the test light ON?
9 Turn the ignition ON with the engine OFF. Con-
nect an unpowered test lamp to B+, probe the
glow plug relay ground circuit (BK).
Is the test light ON?
4-1-00
_______________________________________________________
Glow Plugs Inoperative
Action Value Yes
Go to step 2.
Go to step 3.
5.0-5.6 Volts Go to step 7.
0.9-1.5 Volts
5.6 Volts Go to step 21.
0.3 Volts Go to step 10.
Go to step 8.
Go to the appli-
cable DTC
table.
Go to step 9.
Go to step 10.
®
No
Go to (LINK-
GO TO-
REPAIR-
609502) Glow
Plug System
Type Relearn
Go to step 4.
Go to step 5.
Go to step 6.
Go to step 25.
Go to Diagnos-
tic Aids.
Go to step 16.
Go to step 17.