Hummer H2. Manual - part 734

Inspect for poor connections at the horn relay. Refer
to Testing for Intermittent Conditions and Poor
Connections and Connector Repairs in Wiring
Systems.
Did you find and correct the condition?

Go to Step 21

Go to Step 20

Repair the high resistance in the horn control circuit
or the horn ground circuit. Also, though unlikely, it is
possible that both horns are defective. Refer to
Circuit Testing and Wiring Repairs in Wiring
Systems.
Did you complete the repair?

Go to Step 21

Repair the open or high resistance in the battery
positive voltage circuit of the horn relay coil. Refer to
Circuit Testing and Wiring Repairs in Wiring
Systems.
Did you complete the repair?

Go to Step 21

Repair the open or short to voltage in the horn relay
control circuit. The horn relay control circuit includes
the horn switch. Refer to Circuit Testing and Wiring
Repairs in Wiring Systems.
Did you complete the repair?

Go to Step 21

Repair the open or high resistance in the battery
positive voltage circuit of the horn relay switch. Refer
to Circuit Testing and Wiring Repairs in Wiring
Systems.
Did you complete the repair?

Go to Step 21

Repair the open or high resistance in the horn control
circuit. Refer to Circuit Testing and Wiring Repairs
in Wiring Systems.
Did you complete the repair?

Go to Step 21

Repair the open or high resistance in the horn ground
circuit. Refer to Circuit Testing and Wiring Repairs
in Wiring Systems.
Did you complete the repair?

Go to Step 21

Replace the BCM. Refer to Body Control Module
Replacement in Body Control System.Did you
complete the replacement?

IMPORTANT:

Perform the BCM programming procedure when
replacing the BCM.

Go to Step 21

Replace the horn relay.
Did you complete the replacement?

Go to Step 21

Operate the horns.
Do the horns operate properly?

System OK

Go to Step 1

2004 Hummer H2

2004 ACCESSORIES & EQUIPMENT Horns - Hummer H2

HORNS INOPERATIVE - ONE HORN

Test Description

The number below refers to the step number on the diagnostic table.

9: The horns need maximum current flow to operate properly. A high resistance - greater than 0.5 ohm -
in the horn control circuit or the horn ground circuit could cause operating problems with the horns.
Inspect the circuits for faults that would restrict current flow.

Horns Inoperative - One Horn

Step

Action

Yes

DEFINITION: This diagnostic procedure is for use with systems that have multiple horns in which one
of the horns is inoperative.

Did you perform the Horns Diagnostic System
Check?

Go to Step 2

Go to Diagnostic

System Check -

Horns

Depress the horn switch.
Do all of the horns operate?

Go to Testing for

Intermittent Conditions

and Poor Connections in

Wiring Systems

Go to Step 3

1. Disconnect the inoperative horn.

2. Connect a test lamp between the horn

control circuit and a good ground.

3. Depress and hold the horn switch.

Does the test lamp illuminate?

Go to Step 4

Go to Step 7

1. Connect a test lamp between the horn

control circuit and the horn ground circuit.

2. Depress and hold the horn switch.

Does the test lamp illuminate?

Go to Step 5

Go to Step 8

Inspect for poor connections at the inoperative
horn. Refer to Testing for Intermittent
Conditions and Poor Connections and
Connector Repairs in Wiring Systems.
Did you find and correct the condition?

Go to Step 11

Go to Step 6

1. Connect a 15 amp fused jumper wire

between the positive battery terminal and
the control terminal of the horn.

2. Connect another jumper wire between the

negative battery terminal and the ground
terminal of the horn.

2004 Hummer H2

2004 ACCESSORIES & EQUIPMENT Horns - Hummer H2

HORNS - POOR TONE

Horns - Poor Tone

Does the horn sound?

Go to Step 9

Go to Step 10

Repair the open or poor connection in the horn
control circuit. Refer to Circuit Testing and
Wiring Repairs in Wiring Systems.
Did you complete the repair?

Go to Step 11

Repair the open or poor connection in the horn
ground circuit. Refer to Circuit Testing and
Wiring Repairs in Wiring Systems.
Did you complete the repair?

Go to Step 11

Repair the high resistance in the horn control
circuit or the horn ground circuit of the horn.
Refer to Circuit Testing and Wiring Repairs in
Wiring Systems.
Did you complete the repair?

Go to Step 11

Replace the inoperative horn. Refer to Horn
Replacement .
Did you complete the replacement?

Go to Step 11

Operate the horns.
Do the horns operate properly?

System OK

Go to Step 1

Step

Action

Yes

Did you perform the Horns Diagnostic System Check?

Go to

Step 2

Go to Diagnostic

System Check -

Horns

Depress the horn switch.
Do the horns have a harsh tone or buzzing?

Go to

Step 3

Go to Symptoms -

Horns

1. Test the horn mounting hardware for adequate torque. Refer

to Fastener Tightening Specifications

2. Inspect the horns for debris in the joint where the horns

attach to the vehicle.

orDid you find and correct the condition?

Go to

Step 7

Go to Step 4

1. Connect a 15 amp fuse jumper wire between the positive

battery terminal and the control terminal of the horn.

2. Connect another jumper wire between the negative battery

terminal and the ground terminal of the horn.

Do the horns have a harsh tone or buzzing?

Go to

Step 6

Go to Step 5

Repair the high resistance in the horn control circuit or the horn
ground circuit. Refer to Circuit Testing and Wiring Repairs in
Wiring Systems.

Go to

2004 Hummer H2

2004 ACCESSORIES & EQUIPMENT Horns - Hummer H2

REPAIR INSTRUCTIONS

HORN REPLACEMENT

Removal Procedure

Fig. 4: Horn
Courtesy of GENERAL MOTORS CORP.

Did you complete the repair?

Step 7

Replace the horns. Refer to Horn Replacement .
Did you complete the replacement?

Go to

Step 7

Operate the horns.
Do the horns operate properly?

System

Go to Step 1

2004 Hummer H2

2004 ACCESSORIES & EQUIPMENT Horns - Hummer H2

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