Hummer H1 (2006+). Manual — part 76

OBD-148

On-Board Diagnostics

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7

Test the 12-volt reference circuit 257 (LG) for an open, high re-
sistance or a short to ground between C76 28 and pin A of the
CKP.

Did you find and correct the condition?

Go to Step 16

Go to Step 11

8

Test the CKP signal circuit 256 (BL) for an open, short to ground
or a short to voltage between C77 pin 52 and pin C of the CKP
sensor connector.

Did you find and correct the condition?

Go to Step 16

Go to Step 14

9

Test the CKP signal circuit 256 (BL) for high resistance between
C77 pin 52 and pin C of the CKP sensor connector.

Did you find and correct the condition?

Go to Step 16

Go to Step 10

10

Inspect for poor connections at the CKP sensor.

Did you find and correct the condition?

Go to Step 16

Go to Step 12

11

Inspect for a poor connections at the engine control module
(ECM).

Did you find and correct the condition?

Go to Step 16

Go to Step 14

12

1.

Remove the CKP sensor.

2.

Visually inspect the CKP sensor for the following condi-
tions:

• Physical damage

• Loose or improper installation

• Wiring routed too closely to secondary ignition compo-

nents

3.

The following conditions may cause this DTC to set:

• Electromagnetic interference in the CKP sensor circuits

• Foreign material passing between the CKP sensor and the

reluctor wheel

• Insufficient fuel

Did you find and correct the condition?

Go to Step 16

Go to Step 13

13

Inspect the CKP reluctor wheel for the following conditions:

• Physical damage

• Improper installation

• Excessive endplay or looseness

Did you find and correct the condition?

Go to Step 16

Go to Step 15

14

Replace the faulty ECM.

Did you complete the replacement?

Go to Step 16

15

Replace the faulty CKP sensor.

Did you complete the replacement?

Go to Step 16

Step

Action

Value(s)

Yes

No

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On-Board Diagnostics OBD-149

5745804

16

1.

Clear the DTCs with a scan tool.

2.

Turn OFF the ignition for 30 seconds.

3.

Start the engine.

4.

Operate the vehicle within the Conditions for Running the
DTC. You may also operate the vehicle within the conditions
that you observed from the Freeze Frame/Failure Records.

Did the DTC fail this ignition?

Go to Step 2

Go to Step 17

17

1.

Using the Scan Tool select “Capture Info,” Review Info.” Are
any DTC’s displayed that have not been diagnosed?

Go to the appli-

cable DTC

table.

System OK.

Step

Action

Value(s)

Yes

No

OBD-150

On-Board Diagnostics

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DTC P0336 Crankshaft Position (CKP) Sensor Performance (Figure OBD-43)

Figure OBD-43: Crankshaft Position (CKP) Sensor Circuit

Circuit Description

The hall effect crankshaft position (CKP) sensor signal indicates the crankshaft speed and position. There are 57 teeth on the front
of the crankshaft sprocket, plus a sync gap. The CKP sensor will output an ON-OFF pulse as each window passes the sensing ele-
ment. The CKP sensor is connected directly to the engine control module (ECM) by the following circuits:

• The 12-volt reference circuit

• The low reference circuit

• The CKP sensor signal circuit

Conditions for Setting the DTC

The ECM determines that the CKP sensor signal is out of range for less than 2 seconds.

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On-Board Diagnostics OBD-151

5745804

Action Taken When the DTC Sets

• The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diag-

nostic runs and fails.

• The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the

control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecu-
tive ignition cycle, the control module records the operating conditions at the time of the failure. The control module
writes the operating conditions to the Freeze Frame and updates the Failure Records.

Conditions for Clearing the MIL/DTC

• The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic

runs and does not fail.

• A current DTC, Last Test Failed, clears when the diagnostic runs and passes.

• A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related

diagnostic.

• Clear the MIL and the DTC with a scan tool.

Diagnostic Aids

An intermittent CKP sensor signal may cause DTC P0336 to set. Wiggle the wiring harness with the engine running and observe
the CKP Signal Missed parameter of the scan tool. If the parameter indicates anything other than 0, there is an intermittent condi-
tion.

Step

Action

Value(s)

Yes

No

1

NOTE: 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” per-
formed?

Go to step 2.

Go to OBD Sys-

tem Check.

2

1.

Observe the Freeze Frame/Failure Records data for this
DTC.

2.

Turn OFF the ignition for 30 seconds.

3.

Start the engine.

4.

Operate the vehicle within the Conditions for Running the
DTC. You may also operate the vehicle within the conditions
that you observed from the Freeze Frame/Failure Records.

Did the DTC fail this ignition?

Go to Step 3

Intermittent Go

To Diagnostic

Aids

3

1.

Inspect all of the circuits going to the crankshaft position
(CKP) sensor for the following:

• Routed too closely to fuel injection wiring or components

• Routed too closely to after-market add-on electrical equip-

ment

• Routed too closely to solenoids, relays, and motors

2.

If you find incorrect routing, correct the harness routing.

Did you find and correct the condition?

Go to Step 10

Go to Step 4