Hummer H1 (2006+). Manual - part 46

OBD-28

On-Board Diagnostics

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OBD II DIAGNOSTIC TROUBLE CODES

DTC Identification

OBD II requires that the automotive industry use a standardized Diagnostic Trouble Code (DTC) structure (Figure OBD-3).  This
code structure is very different from OBD I DTC structure. The OBD II DTCs contains a letter and a four-digit number. The letter
identifies the function of the device that has the fault:

• B = Body

• C = Chassis

• P = Powertrain

• U = Network or data link code

The first digit of the number indicates if the DTC is generic or manufacturer-specific (0=generic, 1=specific). The second number
indicates the specific vehicle system that has the fault. Below are the powertrain system identifiers:

• 1 = Fuel and Air Metering

• 2 = Fuel and Air Metering (injector circuit malfunction).

• 3 = Ignition System or Misfire

• 4 = Auxiliary Emission Controls

• 5 = Vehicle Speed Control and Idle Control System

• 6 = Computer Output Circuit

• 7 = Transmission 

• 8 = Transmission

The last two digits indicate the component or section of the system that has the fault.

Figure OBD-3:   OBD II Code Structure

Code Type 

Each DTC is directly related to a diagnostic test. The Diagnostic Management System sets DTCs based on the failure of the tests during a
trip or trips. Certain tests must fail two consecutive trips before the DTC is set. The following are the four types of DTCs and the char-
acteristic of those codes:

Engine mechanical check.

• Check for incorrect basic engine parts such as the cam, the heads, the pistons, etc.

• Check for any excessive oil entering the combustion chamber.

NOTE: Definition: White, black, gray or blue smoke under load, idle or start up hot or cold.

Checks Action

P 0 1 1 7

EXAMPLE: P0117 ECT SENSOR CIRCUIT LOW VOLTAGE

B - BODY
C - CHASSIS
P - POWERTRAIN
U - NETWORK

0 - GENERIC (SAE)
1 - MANUFACTURER

SPECIFIC

SPECIFIC FAULT 

DESIGNATION

SPECIFIC VEHICLE

SYSTEM

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 On-Board Diagnostics  OBD-29

5745804

Type A

• Emissions related.

• Requests illumination of the MIL on the first trip with a failure.

• Stores a HISTORY DTC on the first trip with a failure.

• Stores a Freeze Frame on the first trip with a failure.

• Stores a failure Record.

• Updates the Failure Record the first time the test fails each ignition cycle.

Type B

• Emission related.

• “Armed” after one trip with a failure.

• “Disarmed” after one trip with a pass.

• Requests illumination of the MIL on the second consecutive trip with a failure.

• Stores a HISTORY DTC on the second consecutive trip with a failure (the DTC is “armed” after the first failure).

• Stores a Freeze Frame on the second consecutive trip with a failure.

• Stores a Failure Record when the first test fails (not dependent on consecutive trip fails).

• Updates the Failure Record the first time the test fails each ignition cycle.

Type C

• Non-emission related.

• Request illumination of the service lamp (such as the “CHECK THROTTLE” not the MIL) on the first trip with a failure.

• Stores a HISTORY DTC on the first trip with a failure.

• Does not store a Freeze Frame.

• Stores Failure records when the test fails.

• Updates the Failure Record the first time the test fails each ignition cycle.

Type D

• Non-emission related.

• Does not request illumination of any lamps.

• Stores a History DTC on the first trip with a failure.

• Does not store a Freeze Frame.

• Stores a Failure Record when the test fails.

• Updates the Failure Record the first time the test fails each ignition cycle.

DTC Information

The status of the test and the related DTC messages can be viewed by using the Tech 2. The combination of messages is dependent
on the status of the test.The following is a list of DTC information message (some applications do not display all messages listed
below):

LAST TEST FAILED: 

This message indicates that the last diagnostic test failed. If the DTC is a type A or B this test could have occurred in a previous ig-
nition cycle. This message remains until the test passes or the DTCs are cleared. If the DTC is a type C or D, this message clears
when the ignition is turned “OFF”.

TEST FAILED SINCE CODE CLEARED: 

This message indicates that the test has failed at least once since the DTCs were cleared.

FAILED THIS IGNITION: 

This message indicates that the diagnostic test related to the DTC has failed this ignition cycle.

HISTORY:

OBD-30

On-Board Diagnostics

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This message indicates that the DTC has been stored in memory as a valid fault. Type B DTCs are not stored as history DTCs until
the test has failed two consecutive trips.

MIL REQUEST: 

This message indicates that the DTC has requested illumination of the MIL. Only type A and B DTCs can request illumination of
the MIL. 

NOT RAN SINCE CODE CLEARED: 

This message indicates that the test related to this DTC has not been run uncertain of the status of the system this ignition cycle. A
trip must be completed for the ECM to run the test and know the status of the system.

LAST TEST PASSSED: 

This message indicates that the Diagnostic test that failed previously has passed the latest diagnostic test. This does not indicate
that the failed is gone. It only indicates that the fault was not present during the latest test.

TEST RAN AND PASSED: 

This message indicates that the latest test passed. The test ran and passed this ignition cycle, and ran and passed since DTCs were
cleared. The test has not failed since the DTCs were cleared.

FREEZE FRAME: 

The Diagnostic Executive in the ECM records certain vehicle operating conditions when a type A or B (emission related) DTC is
stored as a history DTC. The ECM only store one Freeze Frame record. Freeze Frame data is stored for the first failed test that sets
the DTC and illuminates the MIL.

Freeze Frame is not updated (refreshed) if the test fails a second time. However, fuel trim and misfire DTCs take priority over all other
DTCs. Fuel trim and misfire DTCs always overwrite the Freeze Frame record unless a fuel trim or misfire DTC is already stored. Any
previous information related to DTCs stored in the Freeze Frame that are overwritten due to a priority DTC setting is lost.

DTC FAIL RECORDS: 

Due to the limitations of the Freeze Frame, Failure Records was created. Failure Records assist the technicians when multiple
DTCs have been set or when the DTC is non-emission related. Failure Records have similar data parameters to those that are stored
in the Freeze Frame. However, the ECM has the ability to store multiple Failure Records.

Failure records are stored any time a diagnostic test fails. Failure Records are only updated (refreshed) the first time the test fails
during each ignition cycle. This includes type B DTCs that fail only one trip. Unlike Freeze Frame, Failure Records are not limited
to emission DTCs. Type C and D Diagnostic Trouble Codes store Failure Records.

The ECM can store up to Five individual DTC Failure Records. When a diagnostic test fails, Failure Records are stored in the ECM
memory and assigned to the first Failure Record position. If a different diagnostic test fails, a second Failure record related to that
DTC is stored in memory. Additional failed diagnostic tests for different DTCs also store Failure Records until Fail Record memory is
full. If more than the maximum number of DTCs are stored, the failure records are replaced on a “first in, first out” basis.

 Diagnostic Trouble Code (DTC) Identification

DTC

Description

Type

Illuminate MIL

P0016

Crankshaft Position (CKP) Camshaft Position (CMP) Sensor Correlation

B

Yes

P0045

Turbocharger Boost Control Circuit

B

Yes

P0046

Turbocharger Boost Control Position Performance

B

Yes

P0087

Fuel Rail Pressure too Low

A

Yes

P0088  

Fuel Rail Pressure too High

A

Yes

P0089

Fuel Rail Pressure Regulator Performance

A

Yes

P0090

Fuel Rail Pressure Control Circuit

A

Yes

P0101

Mass Air Flow (MAF) Sensor Performance 

B

Yes

P0102

Mass Air Flow (MAF) Sensor Ckt Low Voltage

B

Yes

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 On-Board Diagnostics  OBD-31

5745804

P0103

Mass Air Flow (MAF) Sensor Ckt High Voltage

B

Yes

P0112

Intake Air Temperature (IAT) Sensor Circuit Low Voltage

B

Yes

P0113

Intake Air Temperature (IAT) Sensor Circuit High Voltage

B

Yes

P0116

Engine Coolant Rationality

B

Yes

P0117

Engine Coolant Temp (ECT) Sensor Circuit Low Voltage

B

Yes

P0118

Engine Coolant Temp (ECT) Sensor Circuit High Voltage

B

Yes

P0168

Fuel Temperature Sensor Over Temp

D

No

P0181

Fuel Temperature Sensor Performance

B

Yes

P0182

Fuel Temperature Sensor Circuit Low Voltage

B

Yes

P0183

Fuel Temperature Sensor Circuit High Voltage

B

Yes

P0192

Fuel Rail Pressure Sensor Circuit Low Voltage

A

Yes

P0193

Fuel Rail Pressure Sensor Circuit High Voltage

A

Yes

P0201

Injector #1 Control Circuit

A

Yes

P0202

Injector #2 Control Circuit

A

Yes

P0203

Injector #3 Control Circuit

A

Yes

P0204

Injector #4 Control Circuit

A

Yes

P0205

Injector #5 Control Circuit

A

Yes

P0206

Injector #6 Control Circuit

A

Yes

P0207

Injector #7 Control Circuit

A

Yes

P0208

Injector #8 Control Circuit

A

Yes

P0218

Transmission Fluid Over temperature

C

No

P0234

Turbo Charger Engine Overboost 

B

Yes

P0237

Turbo Charger Boost Sensor Circuit Low Voltage

B

Yes

P0238

Turbo Charger Boost Sensor Circuit High Voltage

B

Yes

P0299

Turbo Charger Engine Underboost 

B

Yes

P0300

Engine Misfire Detected

D

Yes

P0301

Cylinder 1 misfire Detected

B

Yes

P0302

Cylinder 2 misfire Detected

B

Yes

P0303

Cylinder 3 misfire Detected

B

Yes

P0304

Cylinder 4 misfire Detected

B

Yes

P0305

Cylinder 5 misfire Detected

B

Yes

P0306

Cylinder 6 misfire Detected

B

Yes

 Diagnostic Trouble Code (DTC) Identification (Continued)

DTC

Description

Type

Illuminate MIL