Content .. 76 77 78 79 ..

Hummer H1 (2006+). Manual - part 78

OBD-156

On-Board Diagnostics

_____________________________________________

Inspect for poor connections at the ECM.

Did you find and correct the condition?

Go to Step 18

Go to Step 17

NOTE: Inspect the CMP sensor for physical damage before re-
placing.

Replace the faulty CMP sensor.

Did you complete the replacement?

Go to Step 18

Replace the faulty ECM.

Did you complete the replacement?

Go to Step 18

Clear the DTCs with a scan tool.

Turn OFF the ignition for 30 seconds.

Start the engine.

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 19

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

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On-Board Diagnostics OBD-157

5745804

DTC P0341 Camshaft Position (CMP) Sensor Performance (Figure OBD-45)

Figure OBD-45: 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 determines that the CMP sensor signal is out of range for less than 2 seconds, DTC P0341 will set.

Conditions for Setting the DTC

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

OBD-158

On-Board Diagnostics

_____________________________________________

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 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.

• Use a scan tool in order to clear the MIL and the DTC.

Diagnostic Aids

• An intermittent CMP sensor signal may cause DTC P0341 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

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.

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

Turn OFF the ignition for 30 seconds.

Start the engine.

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

Test the 5-volt reference circuit 254 (RD) for high resistance be-
tween C75 pin 50 and pin A of the cam sensor connector.

Is the resistance above the specified value?

Did you find and correct the condition?

5ohms

Go to Step 10

Go to Step 4

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On-Board Diagnostics OBD-159

5745804

Inspect all of the circuits going to the camshaft position
(CMP) sensor for the following conditions:

• 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

If you find incorrect routing, correct the harness routing.

Did you find and correct the condition?

Go to Step 10

Go to Step 5

Test for an intermittent and for a poor connection at the CMP
sensor.

Did you find and correct the condition?

Go to Step 10

Go to Step 6

Test for an intermittent and for a poor connection at the ECM.

Did you find and correct the condition?

Go to Step 10

Go to Step 7

Remove the CMP sensor.

Inspect the CMP sensor for signs of damage.

Replace if damaged.

Did you find and correct the condition?

Go to Step 10

Go to Step 8

Inspect the CMP reluctor wheel for damage.

If the CMP reluctor wheel is damaged.

Replace if damaged.

Did you find and correct the condition?

Go to Step 10

Go to Step 9

Replace the faulty CMP sensor.

Did you complete the replacement?

Go to Step 10

Clear the DTCs with a scan tool.

Turn OFF the ignition for 30 seconds.

Start the engine.

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

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

Content .. 76 77 78 79 ..