Hummer H1 (2006+). Manual - part 77

OBD-152

On-Board Diagnostics

_____________________________________________

    4

1.

Turn OFF the ignition.

2.

Disconnect the CKP sensor.

3.

Test the CKP sensor signal circuit for high resistance. 

Did you find and correct the condition?

Go to Step 10 

Go to Step 5 

    5

Test for an intermittent and for a poor connection at the CKP sen-
sor.

Did you find and correct the condition?

Go to Step 10 

Go to Step 6 

    6

Test for an intermittent and for a poor connection of the CKP sen-
sor circuits at the engine control module (ECM).

Did you find and correct the condition?

Go to Step 10 

Go to Step 7 

    7

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:

• Excessive air gap between the CKP sensor and the reluctor 

wheel

• 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 10

Go to Step 8 

    8

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 10 

Go to Step 9 

    9

Replace the faulty CKP sensor. 

Did you complete the replacement?

Go to Step 10 

    10

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 11

   11

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

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 On-Board Diagnostics  OBD-153

5745804

DTC P0340 Camshaft Position (CMP) Sensor Circuit (Figure OBD-44)

Figure OBD-44:   Camshaft Position (CMP) Sensor Circuit

Circuit Description

The hall effect camshaft position (CMP) sensor produces 3 ON-OFF pulses for each revolution of the camshaft. The CMP output is
pulse width encoded. The engine control module (ECM) uses the CMP and crankshaft position (CKP) output pulses to determine
the engine speed and position. The CMP is connected directly to the ECM by the following circuits:

• 5-volt reference 

• Low reference 

• CMP sensor signal 

If the ECM does not see a CMP signal for more than 2 seconds, DTC P0340 will set.

Conditions for Setting the DTC

The ECM does not see a CMP sensor signal for more than 2 seconds.

OBD-154

On-Board Diagnostics

_____________________________________________

Action Taken When the DTC Sets 

• The control module illuminates the malfunction indicator lamp (MIL) when the diagnostic runs and fails. 

• The control module records the operating conditions at the time the diagnostic fails. The control module stores this informa-

tion in the Freeze Frame/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 CMP sensor signal may cause DTC P0340 to set. Wiggle the wiring harness with the engine running and ob-

serve the Cam Signal Missed parameter of the scan tool. If the parameter indicates anything other than 0, there is an in-
termittent condition.

• If the CMP sensor signal is lost while running, the engine will operate normally. If the CMP sensor signal is not present on 

start-up, the engine will not start. 

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

Attempt to start the engine.

Does the engine start and run?

Intermittent Go 

To Diagnostic 

Aids

Go to Step 3 

    3

1.

Turn OFF the ignition.

2.

Disconnect the camshaft position (CMP) sensor. 

3.

Turn ON the ignition, with the engine OFF.

4.

Measure the voltage from the 5-volt reference circuit 254 
(RD) of the CMP sensor to a good ground with a DVOM.

Does the DVOM display a reading within the specified range?

4.8-5.2

Volts

Go to Step 5

Go to Step 4

    4

Does the DVOM display a reading above the specified value?

5.2 Volts

Go to Step 9

Go to Step 8 

    5

1.

Turn OFF the ignition.

2.

Disconnect the engine control module (ECM). 

3.

Measure the resistance of the 5-volt reference circuit 254 
(RD) between C75 pin 50 and pin A of the CMP sensor with 
a DVOM.

Is the resistance above the specified value?

5 ohms

Go to Step 10

Go to Step 6 

_____________________________________________

 On-Board Diagnostics  OBD-155

5745804

    6

1.

Connect the ECM.

2.

Connect a jumper wire between each of the terminals in the 
CMP sensor harness connector and the corresponding termi-
nals at the CMP sensor. 

3.

Turn ON the ignition, with the engine OFF.

4.

Measure the voltage from the low reference circuit 156 (PK/
BK) of the CMP sensor at the jumper wire terminal to a good 
ground with a DVOM.

is the voltage more than the specified value?

0.2 Volts

Go to Step 11 

Go to Step 7 

    7

1.

Turn OFF the ignition.

2.

Remove the jumper wires from the CMP sensor.

3.

Turn ON the ignition, with the engine OFF.

4.

Observe the Cam Signal Present parameter with a scan tool.

5.

Momentarily and repeatedly probe the signal circuit 253 
(BR/WH) of the CMP sensor with a test lamp that is con-
nected to battery voltage.

Does the Cam Signal Present parameter change when the test
lamp contracts the signal circuit?

Go to Step 12 

Go to Step 13

    8

Test the CMP sensor 5-volt reference circuit 254 (RD) for an
open or a short to ground between C75 pin 50 and pin A of the
cam sensor connector. 

Did you find and correct the condition?

Go to Step 18

Go to Step 15

    9

Test the CMP sensor 5-volt reference circuit 254 (RD) for a short
to voltage between C75 pin 50 and pin A of the cam sensor con-
nector.

Did you find and correct the condition?

Go to Step 18 

Go to Step 15 

    10

Repair the high resistance in the CMP sensor 5-volt reference cir-
cuit 254 (RD). 

Did you complete the repair?

Go to Step 18 

    11

Test the CMP sensor low reference circuit 156 (PK/BK) for an
open or for high resistance between C75 pin 8 and pin B of the
cam sensor connector.

Did you find and correct the condition?

Go to Step 18

Go to Step 15 

    12

Test the CMP sensor signal circuit 253 (BR/WH) for high resis-
tance between C77 pin 51 and pin C of the cam sensor connector. 

Did you find and correct the condition?

Go to Step 18 

Go to Step 14

    13

Test the CMP sensor signal for the following conditions: 

• An open 

• A short to ground 

• A short to voltage 

• High resistance

Did you find and correct the condition?

Go to Step 18 

Go to Step 15 

    14

Inspect for poor connections at the CMP sensor. 

Did you find and correct the condition?

Go to Step 18

Go to Step 16

Step

Action

Value(s)

Yes

No