Hummer H1 (2006+). Instruction - page 46
OBD-28
On-Board Diagnostics
_______________________________________________
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
______________________________________________
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
_______________________________________________
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
______________________________________________
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