Hummer H1 (2006+). Manual - part 86

OBD-188

On-Board Diagnostics

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DTC P0523 Oil Pressure Sensor High Voltage (Figure OBD-54)

Figure OBD-54:   Oil Pressure Sensor Circuit

Circuit Description

The engine oil pressure (EOP) sensor changes resistance based on engine oil pressure. The engine control module (ECM) monitors
the signal circuit of the EOP sensor. When the oil pressure is high, the sensor resistance is high, and the ECM senses a high signal
voltage. When the oil pressure is low, the sensor resistance is low, and the ECM senses a low signal voltage. The ECM sends the
engine oil pressure information to the instrument panel cluster (IPC) via the class 2 serial data circuit.

Conditions for Setting the DTC 

• The ECM detects that the EOP sensor signal circuit is greater than 4.6 volts. 

• The above condition is present for greater than 9 seconds. 

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 On-Board Diagnostics  OBD-189

5745804

Action Taken When the DTC Sets

The ECM records the operating conditions at the time that the diagnostic test fails. The ECM displays this information in the Fail-
ure Records on the scan tool.

Conditions for Clearing the DTC 

• The DTC becomes history when the conditions for setting the DTC are no longer present. 

• The history DTC is cleared after 40 malfunction free warm-up cycles. 

• The ECM receives the clear code command from the scan tool. 

Diagnostic Aids 

Using the Failure Records data may help locate an intermittent condition. If you cannot duplicate the DTC, the information in the
Failure Records can help in determining how many miles since the DTC set. The Fail Counter and the Pass Counter can help deter-
mine how many ignition cycles that the diagnostic test reported a pass and/or a fail.

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.

Install a scan tool.

2.

Turn the ignition ON, with the engine OFF.

3.

With the scan tool, observe the Engine Oil Pressure Sensor 
parameter in the ECM Engine Data 2 data list. 

Does the scan tool indicate that the Engine Oil Pressure parame-
ter is at or greater than the specified value

550 kPa 

(80 psi)

4.6 Volts

Go to Step 3 

Intermittent Go 

to Diagnostic 

Aids

    3

1.

Turn the ignition OFF.

2.

Disconnect the engine oil pressure (EOP) sensor.

3.

With the scan tool, observe the Engine Oil Pressure Sensor 
parameter in the ECM Engine Data 2 data list. 

Does the scan tool indicate that the Engine Oil Pressure parame-
ter is at or less than the specified value?

0 kPa (0 

psi)

0.4 V

Go to Step 4 

Go to Step 5 

    4

1.

Turn the ignition OFF.

2.

Disconnect the negative battery cable. 

3.

Measure the resistance from the low reference circuit 618 
(BK) of the EOP sensor to a good ground.

Is the resistance less than the specified value?

5 ohms

Go to Step 7 

Go to Step 6 

    5

Test the EOP sensor signal circuit 619(TN/WH) for a short to
voltage.

Did you find and correct the condition?

Go to Step 11 

Go to Step 8 

    6

1.

Disconnect the engine control module (ECM).

2.

Test the low reference circuit 618 (BK) of the EOP sensor for 
an open or for a high resistance between C76 pin 39 and pin 
A of the EOP sensor connector. 

Did you find and correct the condition?

Go to Step 11 

Go to Step 8

OBD-190

On-Board Diagnostics

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    7

Inspect for poor connections at the harness connector of the EOP
sensor.

Did you find and correct the condition?

Go to Step 11

Go to Step 9

    8

Inspect for poor connections at the harness connector of the
ECM.

Did you find and correct the condition?

Go to Step 11

Go to Step 10

    9

Replace the faulty engine oil pressure sensor. 

Did you complete the replacement?

Go to Step 12 

    10

Replace the faulty ECM. 

Did you complete the replacement?

Go to Step 12

    11

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 12

   12

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-191

5745804

DTC P0561 System Voltage Performance (Figure OBD-55)

Figure OBD-55:   External Fuse Box Circuit

Circuit Description

The transmission control module (TCM) requires a switched ignition voltage input and a direct battery voltage input. 

DTC P0561 is a type C DTC.

Conditions for Setting the DTC

DTC P0561 sets when the TCM detects a large variation in ignition voltage or battery direct voltage. When an ignition or battery
direct voltage variation of 4.0 volts or greater is detected for 0.5 second, a fault pending is reported. After 1.0 second of 4.0 volts or
greater variation, a DTC is set with a failure response. 

Action Taken When the DTC Sets 

• The TCM does not illuminate the malfunction indicator lamp (MIL). 

• The transmission fails to hydraulic default. 

• DTC P0561 will be stored in TCM history. 

• The TCM inhibits torque converter clutch (TCC) engagement. 

• The TCM freezes shift adapts