Hummer H2. Manual - part 1340

Coil

Antenna

 

2004 Hummer H2 

2004 ACCESSORIES & EQUIPMENT Wiring Systems - Hummer H2

  

Twisted Wires

Shield

Switches

Single Pole/Throw Relay - Normally Open

 

2004 Hummer H2 

2004 ACCESSORIES & EQUIPMENT Wiring Systems - Hummer H2

  

GENERAL ELECTRICAL DIAGNOSIS PROCEDURES 

Basic Knowledge Required 

Without a basic knowledge of electricity, it will be difficult to use the diagnostic procedures contained in the 
service manual. You should understand the basic theory of electricity, and know the meaning of voltage (volts), 
current (amps), and resistance (ohms). You should also be able to read and understand a wiring diagram, as well 
as understand what happens in a circuit with an open or a shorted wire. 

CHECKING AFTERMARKET ACCESSORIES 

Do not connect aftermarket accessories into the following circuits: 

z

SIR circuits, all such circuits are indicated on circuit diagrams with the SIR symbol. 

z

OBD II circuits, all such circuits are indicated on circuit diagrams with the OBD II symbol.  

Always check for aftermarket accessories (non-OEM) as the first step in diagnosing electrical problems. If the 
vehicle is so equipped, disconnect the system to verify that these add-on accessories are not the cause of the 
problems. 

Possible causes of vehicle problems related to aftermarket accessories include: 

z

Power feeds connected to points other than the battery  

z

Antenna location  

z

Transceiver wiring located too close to vehicle electronic modules or wiring  

z

Poor shielding or poor connectors on antenna feed line  

z

Check for recent service bulletins detailing installation guidelines for aftermarket accessories. 

Single Pole/Throw Relay - Normally Closed

CAUTION: Refer to SIR Caution in Cautions and Notices.

NOTE:

Refer to OBD II Symbol Description Notice in Cautions and Notices.

 

2004 Hummer H2 

2004 ACCESSORIES & EQUIPMENT Wiring Systems - Hummer H2

  

CIRCUIT TESTING 

The Circuit Testing section contains the following diagnostic testing information. Using this information along 
with the diagnostic procedures will identify the cause of the electrical malfunction. 

z

Using Connector Test Adapters  

z

Probing Electrical Connectors  

z

Troubleshooting with a Digital Multimeter  

z

Troubleshooting with a Test Lamp  

z

Using Fused Jumper Wires  

z

Measuring Voltage  

z

Measuring Voltage Drop  

z

Measuring Frequency  

z

Testing for Continuity  

z

Testing for Short to Ground  

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Testing for a Short to Voltage  

USING CONNECTOR TEST ADAPTERS 

PROBING ELECTRICAL CONNECTORS 

Frontprobe 

Disconnect the connector and probe the terminals from the mating side (front) of the connector. 

NOTE:

Do not insert test equipment probes (DVOM etc.) into any connector or fuse 
block terminal. The diameter of the test probes will deform most terminals. A 
deformed terminal will cause a poor connection, which will result in a system 
failure. Always use the J-35616 GM-Approved Terminal Test Kit or the J 42675 
Flat-Wire Probe Adapter in order to front probe terminals. Do not use paper 
clips or other substitutes to probe terminals. 
When using the J-35616 GM-Approved Terminal Test Kit, ensure the terminal 
test adapter choice is the correct size for the connector terminal. Do not 
visually choose the terminal test adapter because some connector terminal 
cavities may appear larger than the actual terminal in the cavity. Using a larger 
terminal test adapter will damage the terminal. Refer to the J-35616 GM-
Approved Terminal Test Kit label on the inside of the J-35616 GM-Approved 
Terminal Test Kit for the correct adapter along with the connector end view for 
terminal size.

IMPORTANT: Always be sure to reinstall the connector position assurance (CPA) and 

terminal position assurance (TPA) when reconnecting connectors or replacing 
terminals.

 

2004 Hummer H2 

2004 ACCESSORIES & EQUIPMENT Wiring Systems - Hummer H2