Hummer H1 (2006+). Manual - part 340

12-36

Electrical System

_______________________________________________________

6

Inspect for poor connections at the starter. 
Did you find and correct the condition?

Go to Step 8. 

Go to Step 7. 

7

Replace the fulty Starter. 
Did you complete the replacement?

Go to Step 8. 

8

Operate the system for which the symptom occurred.
Did you correct the condition?

System OK.

Go to Step 2.

 Starter Solenoid Does Not Click   (Figure 12-145)

Step

Action

Value(s)

Yes

No

1

Did you preform the Diagnostic System Check?

Go to step 2. 

Go to diagnostic sys-

tem check.

2

Turn the ignition switch to the START position.
Does the engine crank?

Intermittent condi-

tion, poor connec-

tions in wiring.

Go to step 3. 

3

Turn the ignition switch to the START position.
Does the starter motor relay click?

Go to step 11. 

Go to step 4.

4

1.

Turn OFF the ignition.

2.

Disconnect the ECM harness connector C-77.

3.

Connect a test lamp between pin 18 (CKT 331 WH) 
of the ECM harness and a good ground.

4.

With the transmission in park, turn the ignition 
switch to the START position.

Does the test light illuminate?

Go to step 7.

Go to step 5.

5

Inspect for poor connections at the ECM  connector pins 
18 and 35, exterior fuse box #1 40 amp maxi fuse, or 
ignition switch connector pin ST (CKT 33 WH).
Did you find and correct the condition ?

Go to step 29.

Go to step 6.

6

Test circuit 37 and crank fuse # 1 in exterior fuse box for 
an open or high resistance.
Did you find and correct the condition ?

Go to step 29.

Go to step 27.

7

1.

Turn OFF  the ignition.

2.

Disconnect the ECM harness connector C-77.

3.

Connect A test lamp between the pin 35 (CKT 332
BK) and a good ground.

4.

Turn the ignition to the START position.

 Does the test light illuminate?

Go to step 19.

Go to step 8.

 Starter Solenoid Click, Engine Does Not Crank

Step

Action

Value(s)

Yes

No

______________________________________________________

 Electrical System  12-37

8

1.

Remove the starter motor relay.

2.

Connect a test lamp from pin 87 (CKT 37 YL) and a
good ground.

Turn the ignition to the START position.

Does the test light illuminate?

Go to step 9.

Go to step 10.

9

1.

Connect a test lamp from pin 85 (CKT 332 BK) to a 
good ground.

2.

Turn the ignition to the START position.

Does the test light illuminate?

Go to step 17.

Go to step 14.

10

1.

Turn OFF the ignition.

2.

Disconnect the neutral start back up switch (NSBU).

3.

Turn ON the ignition, with the engine OFF.

4.

Connect a 10-amp fused jumper to pin 1 (CKT 331
WH).

5.

Turn the ignition switch to the START position.

Does the test light illuminate?

Go to step 18.

Go to step 15.

11

1.

Turn OFF the ignition.

2.

Disconnect the starter motor relay.

3.

Connect a test lamp to pin 87 (CKT 37 YL) and a
good ground.

Does the test light illuminate?

Go to step 12.

Go to step 23.

12

Connect a 30-amp fused jumper to pin 30 (CKT 34 LB).
Does the engine crank?

Go to step 17.

Go to step 13.

13

Does the fuse in the jumper open?

Go to step 24.

Go to step 16.

14

Test circuit 332 BK for an open or high resistance.
Did you find and correct the condition ?

Go to step 29.

Go to step 25.

15

Test circuit 33 WH for an open or high resistance.
Did you find and correct the condition ?

Go to step 29.

Go to step 21.

16

Test circuit 37 YL for an open or high resistance.
Did you find and correct the condition ?

Go to step 29.

Go to step 22.

17

Inspect for poor connections at the starter motor relay.
Did you find and correct the condition ?

Go to step 29.

Go to step 25.

18

Inspect for poor  connection at the NSBU switch harness 
connector. If OK perform NSBU adjustment procedure 
in SECTION 5 of the service manual.
Did you find and correct the condition ?

Go to step 29.

Go to step 26.

 Starter Solenoid Does Not Click (Cont’d)  (Figure 12-145)

Step

Action

Value(s)

Yes

No

12-38

Electrical System

_______________________________________________________

19

Inspect for poor  connection at the ECM  harness connec-
tor C-77.
Did you find and correct the condition ?

Go to step 29.

Go to step 20.

20

Replace the ECM.
Did you complete the replacement?

Go to step 29.

–

21

Inspect for a poor connection at the ignition switch har-
ness connector  pin ST(CKT 33 WH).
Did you find and correct the condition ?

Go to step 29.

Go to step 27.

22

Inspect for poor connections at the starter solenoid.
Did you find and correct the condition ?

Go to step 29.

Go to step 28.

23

Repair the open or high resistance in circuit 37 YL.
Did you find and correct the condition ?

Go to step 29.

–

24

Repair the short to ground in circuit 34 LB.
Did you find and correct the condition ?

Go to step 29.

–

25

Replace the starter relay.
Did you complete the replacement?

Go to step 29.

–

26

Replace the NSBU switch.
Did you complete the replacement?

Go to step 29.

–

27

Replace the ignition switch.
Did you complete the replacement?

Go to step 29.

–

28

Replace the starter.
Did you complete the replacement?

Go to Step 29.

–

29

Operate the system for which the symptom occurred.
Did you correct the condition?

system OK.

Go to Step 2.

 Glow Plugs Inoperative   (Figure 12-117)

Step

Action

Value

Yes

No

1.

Before clearing any DTC’s, use the scan tool Cap-
ture Info to save the Freeze Frame and Failure 
Records for reference. The ECM’s data is deleted 
once the Clear Info function is used. 
Did you perform the On-Board Diagnostic (OBD) 
System Check?

Go to step 2.

2.

If DTC P0380 is set after a ECM 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?

Go to step 3.

Go to (LINK-

GO TO-

REPAIR-

609502) Glow 

Plug System 

Type Relearn

 Starter Solenoid Does Not Click (Cont’d)  (Figure 12-145)

Step

Action

Value(s)

Yes

No

______________________________________________________

 Electrical System  12-39

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 scan tool display a voltage near the first 
specified value with the glow plug commanded 
ON and near the second specified value with the 
glow plug commanded OFF?

5.0-5.6 Volts

0.9-1.5 Volts

Go to step 7.

Go to step 4.

4.

Does the scan tool display a glow plug voltage 
greater than the specified value?

5.6 Volts

Go to step 21.

Go to step 5.

5.

Does the scan tool display a glow plug voltage 
greater than the specified value?

0.3 Volts

Go to step 10.

Go to step 6.

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?

Go to step 8.

Go to step 25.

7.

The DTC is intermittent. If any additional DTC’s 
were stored, refer to those table(s).
Were there any additional DTC’s stored?

Go to the appli-

cable DTC 

table.

Go to Diagnos-

tic Aids.

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 RD).
Is the test light ON?

Go to step 9.

Go to step 16.

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?

Go to step 10.

Go to step 17.

10.

Turn the ignition ON with the engine OFF. Verify 
that the glow plug relay control harness is discon-
nected. With a DMM connected to ground, probe 
the glow plug relay control circuit (466 YL) at the 
glow plug relay harness connector. Use a scan 
tool to command the glow plugs ON and OFF.
Does the DMM display a voltage near the first 
specified value with the glow plugs commanded 
ON and near the second specified voltage with 
glow plugs commanded OFF?

9-12 Volts

0 volts

Go to step 12.

Go to step 11.

11.

Is the voltage equal to or more than the specified 
value all the time?

1.0 Volt

Go to step 23.

Go to step 18.

 Glow Plugs Inoperative (Cont’d)  (Figure 12-117)

Step

Action

Value

Yes

No