Hummer H2. Manual — part 1266

If this is unsuccessful, use local cooling treatments such as ice or a venturi type nozzle (one that provides hot or
cold air). This type of tool is capable of producing air stream temperatures down to -18°C (0°F) from one end
and 71°C (160°F) from the other. This is ideally suited for localized cooling needs.

Once the vehicle, component, or harness has been sufficiently cooled, manipulate the harness or components in
an effort to duplicate the concern.

TESTING FOR ELECTRICAL INTERMITTENTS

Perform the following procedures while wiggling the harness from side to side. Continue this at convenient
points (about 6 inches apart) while watching the test equipment.

z

Testing for Short to Ground

z

Testing for Continuity

z

Testing for a Short to Voltage

If the fault is not identified, perform the procedure below using the MIN MAX feature on the J 39200 DMM.
This feature allows you to manipulate the circuit without having to watch the J 39200 . The J 39200 will
generate an audible tone when a change is detected.

1. Connect the J 39200 to both sides of a suspected connector (still connected), or from one end of a

suspected circuit to the other. Refer to Troubleshooting with a Digital Multimeter for information on
connecting the J 39200 to the circuit.

2. Set the rotary dial of the J 39200 to the V (AC) or V (DC) position.

3. Press the range button of the J 39200 in order to select the desired voltage range.

4. Press the MIN MAX button of the J 39200 . The J 39200 displays 100 ms RECORD and emits an

audible tone (beep).

5. Simulate the condition that is potentially causing the intermittent connection, either by wiggling the

connections or the wiring, test driving, or performing other operations. Refer to Inducing Intermittent
Fault Conditions .

6. Listen for the audible Min Max Alert which indicates that a new minimum or maximum value has been

recorded.

7. Press the MIN MAX button once in order to display the MAX value and note the value.

8. Press the MIN MAX button again in order to display the MIN value and note the value.

9. Determine the difference between the MIN and MAX values.

IMPORTANT: The J 39200 must be used in order to perform the following procedure since

the J 39200 can monitor current, resistance or voltage while recording the
minimum (MIN), and maximum (MAX) values measured.

IMPORTANT: The 100 ms RECORD mode is the length of time an input must stay at a

new value in order to record the full change.

2004 Hummer H2

2004 ACCESSORIES & EQUIPMENT Wiring Systems - Hummer H2

z

If the variation between the recorded MIN and MAX voltage values is 1 volt or greater an
intermittent open or high resistance condition exists. Repair the condition as necessary.

z

If the variation between the recorded MIN and MAX voltage values is less than 1 volt an
intermittent open or high resistance condition does not exist.

SCAN TOOL SNAPSHOT PROCEDURE

Snapshot is a recording of what a control module on the vehicle was receiving for information while the
snapshot is being made. A snapshot may be used to analyze the data during the time a vehicle condition is
current. This allows you to concentrate on making the condition occur, rather than trying to view all the data in
anticipation of the fault. The snapshot contains information around a trigger point that you have determined.
Only a single data list may be recorded in each snapshot. The Scan Tool has the ability to store 2 snapshots.
The ability to record 2 snapshots allows comparing hot versus cold and good versus bad vehicle scenarios. The
snapshots are stored on a first-in, first-out basis. If a third snapshot is taken, the first snapshot stored in the
memory will be lost.

Snapshots can be 1 of 2 types:

z

Snapshot - taken from the Snapshot menu choice

z

Quick Snapshot - taken from the Data Display soft key choice, does not contain DTC information

When a snapshot is taken, it is recorded on the memory card and may contain as many as 1200 frames of
information. Because the snapshot is recorded onto the memory card, snapshots are not lost if the Scan Tool is
powered down.

The snapshot replay screen has a plot soft key that can be of great value for intermittent diagnosis. The snapshot
plot feature can help you to quickly determine if a sensor is outside of its expected values by plotting 3
parameters at a time. The data will be displayed both graphically and numerically showing the minimum and
maximum values for all frames captured. This is helpful, especially if the fault occurs only once and does not
set a DTC.

CIRCUIT PROTECTION - FUSES

2004 Hummer H2

2004 ACCESSORIES & EQUIPMENT Wiring Systems - Hummer H2

Fig. 3: View Of Good Fuse & Open (Melted) Fuse
Courtesy of GENERAL MOTORS CORP.

The fuse is the most common method of an automotive wiring circuit protection. Whenever there is an
excessive amount of current flowing through a circuit the fusible element will melt and create an open or
incomplete circuit. Fuses are an one time protection device and must be replaced each time the circuit is
overloaded. To determine if a fuse is open, remove the suspected fuse and examine the element in the fuse for
an open (2). If not broken (1), also check for continuity using a DMM or a continuity tester. If the element is
open or continuity is suspect, replace the fuse with one of equal current rating.

Fuse Types

Current Rating Amperes

Color

Auto Fuses, Mini Fuses

2

Gray

3

Violet

5

Tan

7.5

Brown

10

Red

15

Blue

20

Yellow

25

White or Natural

30

Green

Maxi Fuses

20

Yellow

2004 Hummer H2

2004 ACCESSORIES & EQUIPMENT Wiring Systems - Hummer H2

CIRCUIT PROTECTION - CIRCUIT BREAKERS

A circuit breaker is a protective device that is designed to open the circuit when a current load is in excess of the
rated breaker capacity. If there is a short or other type of overload condition in the circuit, the excessive current
will open the circuit between the circuit breaker terminals. Two types of circuit breakers are used.

Circuit Breaker

This type opens when excessive current passes through it for a period of time. It closes again after a few
seconds, and if the cause of the high current is still present, it will open again. The circuit breaker will
continue to cycle open and closed until the condition causing the high current is removed.

Positive Temperature Coefficient (PTC) Circuit Breaker

This type greatly increases its resistance when excessive current passes through it. The excessive current
heats the PTC device, as the device heats its resistance increases. Eventually the resistance gets so high
that the circuit is effectively open. Unlike the ordinary circuit breaker the PTC unit will not reset until the
circuit is opened, by removing the voltage from its terminals. Once the voltage is removed the circuit
breaker will re-close within a second or 2.

CIRCUIT PROTECTION - FUSIBLE LINKS

Fusible link is wire designed to melt and break continuity when excessive current is applied. It is often located
between or near the battery and starter or electrical center. Use a continuity tester or a DMM at each end of the
wire containing the fusible link in order to determine if it is broken. If broken, it must be replaced with fusible
link of the same gauge size.

Repairing a Fusible Link

Refer to Splicing Copper Wire Using Splice Clips .

WIRING REPAIRS

The Wiring Repairs section contains the following types of wiring repair information. Using these elements
together will make wiring repair faster and easier:

z

Circuit Protection - Fuses

30

Light Green

40

Orange or Amber

60

Blue

50

Red

IMPORTANT: Fusible links cut longer than 225 mm (approximately 9 in) will not provide

sufficient overload protection.

2004 Hummer H2

2004 ACCESSORIES & EQUIPMENT Wiring Systems - Hummer H2