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Klaus · #7 03-03-2004, 10:30 PM

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<TD align=middle width="50%">Document ID# 644920
2003 HUMMER
H2
</TD>
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<H1>Horns Inoperative</H1><A name=ss1-644920><A
href="http://127.0.0.1:9001/servlets/BlobShtml?ShtmlFile=644920&psdid=293&evc=s m#ss1-644920">
<H5>Test Description</A></H5>

The numbers below refer to the step numbers on the diagnostic table.

<A name=TD04>
<LI value=4>

Verifies that the body control module (BCM) is providing ground to the horn
relay.<A name=TD05>
<LI value=5>

Tests for voltage at the battery positive voltage terminal of the horn
relay coil.<A name=TD07>
<LI value=7>

Tests for voltage at the battery positive voltage terminal of the horn
relay switch. The HORN fuse supplies power to the battery positive voltage
terminal of the horn relay switch.<A name=TD13>
<LI value=13>

The horns need maximum current flow to operate properly. A high resistance
(greater than 0.5ohms) 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.<A name=TD15>
<LI value=15>

The horn relay control circuit includes the horn switch. The horn switch
must be tested for a high resistance, an open or a short to voltage when
testing the relay control circuit. </LI>

<TABLE width="100%" border=1>
<TBODY>
<TR>
<TH vAlign=center align=middle>

Step</TH>
<TH vAlign=bottom align=middle>

Action</TH>
<TH vAlign=bottom align=middle>

Yes</TH>
<TH vAlign=bottom align=middle>

No</TH></TR>
<TR>
<TD vAlign=center align=middle><A name=S01>

1</A></TD>
<TD vAlign=top align=left>

Did you perform the Horns Diagnostic System Check?</TD>
<TD vAlign=bottom align=middle>

Go to Step2
</TD>
<TD vAlign=bottom align=middle>

Go to <A
href="http://127.0.0.1:9001/servlets/CellHandler?CellId=48491&RefDoc=644920">Diagno stic
System Check - Horns</A> </TD></TR>
<TR>
<TD vAlign=center align=middle><A name=S02>

2</A></TD>
<TD vAlign=top align=left>

Depress the horn switch.

Do the horns operate?</TD>
<TD vAlign=bottom align=middle>

Go to Step3
</TD>
<TD vAlign=bottom align=middle>

Go to Step5
</TD></TR>
<TR>
<TD vAlign=center align=middle><A name=S03>

3</A></TD>
<TD vAlign=top align=left>

<LI type=1>Install a scan tool.
<LI type=1>Turn ON the ignition, with the engine OFF.
<LI type=1>With a scan tool, command the body control module (BCM) Horn
Output ON and OFF. </LI>

Do the horns operate?</TD>
<TD vAlign=bottom align=middle>

Go to <A
href="http://127.0.0.1:9001/servlets/CellHandler?CellId=62112&RefDoc=644920">Testin g
for Intermittent and Poor Connections</A> in Wiring Systems</TD>
<TD vAlign=bottom align=middle>

Go to Step4
</TD></TR>
<TR>
<TD vAlign=center align=middle><A name=S04>

4
</A></TD>
<TD vAlign=top align=left>

Test the BCM portion of the horn relay control circuit for a high
resistance or an open. Refer to <A
href="http://127.0.0.1:9001/servlets/CellHandler?CellId=62194&RefDoc=644920">Circui t
Testing</A> and <A
href="http://127.0.0.1:9001/servlets/CellHandler?CellId=61965&RefDoc=644920">Wiring
Repairs</A> in Wiring Systems.

Did you find and correct the condition?</TD>
<TD vAlign=bottom align=middle>

Go to Step21
</TD>
<TD vAlign=bottom align=middle>

Go to Step11
</TD></TR>
<TR>
<TD vAlign=center align=middle><A name=S05>

5
</A></TD>
<TD vAlign=top align=left>

<LI type=1>Turn OFF the ignition.
<LI type=1>Disconnect the horn relay.
<LI type=1>Connect a test lamp between the battery positive voltage
circuit of the horn relay coil and a good ground. </LI>

Does the test lamp illuminate?</TD>
<TD vAlign=bottom align=middle>

Go to Step6
</TD>
<TD vAlign=bottom align=middle>

Go to Step14
</TD></TR>
<TR>
<TD vAlign=center align=middle><A name=S06>

6</A></TD>
<TD vAlign=top align=left>

<LI type=1>Connect a test lamp between the battery positive voltage
circuit of the horn relay coil and the horn relay control circuit.
<LI type=1>Depress and hold the horn switch. </LI>

Does the test lamp illuminate?</TD>
<TD vAlign=bottom align=middle>

Go to Step7
</TD>
<TD vAlign=bottom align=middle>

Go to Step15
</TD></TR>
<TR>
<TD vAlign=center align=middle><A name=S07>

7
</A></TD>
<TD vAlign=top align=left>

Connect a test lamp between the battery positive voltage circuit of the
horn relay switch and a good ground.

Does the test lamp illuminate?</TD>
<TD vAlign=bottom align=middle>

Go to Step8
</TD>
<TD vAlign=bottom align=middle>

Go to Step16
</TD></TR>
<TR>
<TD vAlign=center align=middle><A name=S08>

8</A></TD>
<TD vAlign=top align=left>

Momentarily connect a 15 amp fused jumper wire between the battery
positive voltage circuit of the horn relay switch and the horn control
circuit.

Do the horns operate?</TD>
<TD vAlign=bottom align=middle>

Go to Step12
</TD>
<TD vAlign=bottom align=middle>

Go to Step9
</TD></TR>
<TR>
<TD vAlign=center align=middle><A name=S09>

9</A></TD>
<TD vAlign=top align=left>

<LI type=1>Reconnect the horn relay.
<LI type=1>Disconnect either horn connector.
<LI type=1>Connect a test lamp between the horn control circuit and a
good ground.
<LI type=1>Depress and hold the horn switch. </LI>

Does the test lamp illuminate?</TD>
<TD vAlign=bottom align=middle>

Go to Step10
</TD>
<TD vAlign=bottom align=middle>

Go to Step17
</TD></TR>
<TR>
<TD vAlign=center align=middle><A name=S10>

10</A></TD>
<TD vAlign=top align=left>

<LI type=1>Connect a test lamp between the horn control circuit and the
horn ground circuit.
<LI type=1>Depress and hold the horn switch. </LI>

Does the test lamp illuminate?</TD>
<TD vAlign=bottom align=middle>

Go to Step13
</TD>
<TD vAlign=bottom align=middle>

Go to Step18
</TD></TR>
<TR>
<TD vAlign=center align=middle><A name=S11>

11</A></TD>
<TD vAlign=top align=left>

Inspect for poor connections at the harness connector of the BCM. Refer
to <A
href="http://127.0.0.1:9001/servlets/CellHandler?CellId=62112&RefDoc=644920">Testin g
for Intermittent and Poor Connections</A> and <A
href="http://127.0.0.1:9001/servlets/CellHandler?CellId=61973&RefDoc=644920">Connec tor
Repairs</A> in Wiring Systems.

Did you find and correct the condition?</TD>
<TD vAlign=bottom align=middle>

Go to Step21
</TD>
<TD vAlign=bottom align=middle>

Go to Step19
</TD></TR>
<TR>
<TD vAlign=center align=middle><A name=S12>

12</A></TD>
<TD vAlign=top align=left>

Inspect for poor connections at the horn relay. Refer to <A
href="http://127.0.0.1:9001/servlets/CellHandler?CellId=62112&RefDoc=644920">Testin g
for Intermittent and Poor Connections</A> and <A
href="http://127.0.0.1:9001/servlets/CellHandler?CellId=61973&RefDoc=644920">Connec tor
Repairs</A> in Wiring Systems.

Did you find and correct the condition?</TD>
<TD vAlign=bottom align=middle>

Go to Step21
</TD>
<TD vAlign=bottom align=middle>

Go to Step20
</TD></TR>
<TR>
<TD vAlign=center align=middle><A name=S13>

13
</A></TD>
<TD vAlign=top align=left>

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 <A
href="http://127.0.0.1:9001/servlets/CellHandler?CellId=62194&RefDoc=644920">Circui t
Testing</A> and <A
href="http://127.0.0.1:9001/servlets/CellHandler?CellId=61965&RefDoc=644920">Wiring
Repairs</A> in Wiring Systems.

Did you complete the repair?</TD>
<TD vAlign=bottom align=middle>

Go to Step21
</TD>
<TD vAlign=center align=middle>

--</TD></TR>
<TR>
<TD vAlign=center align=middle><A name=S14>

14</A></TD>
<TD vAlign=top align=left>

Repair the open or high resistance in the battery positive voltage
circuit of the horn relay coil. Refer to <A
href="http://127.0.0.1:9001/servlets/CellHandler?CellId=62194&RefDoc=644920">Circui t
Testing</A> and <A
href="http://127.0.0.1:9001/servlets/CellHandler?CellId=61965&RefDoc=644920">Wiring
Repairs</A> in Wiring Systems.

Did you complete the repair?</TD>
<TD vAlign=bottom align=middle>

Go to Step21
</TD>
<TD vAlign=center align=middle>

--</TD></TR>
<TR>
<TD vAlign=center align=middle><A name=S15>

15
</A></TD>
<TD vAlign=top align=left>

Repair the open or short to voltage in the horn relay control circuit.
The horn relay control circuit includes the horn switch. Refer to <A
href="http://127.0.0.1:9001/servlets/CellHandler?CellId=62194&RefDoc=644920">Circui t
Testing</A> and <A
href="http://127.0.0.1:9001/servlets/CellHandler?CellId=61965&RefDoc=644920">Wiring
Repairs</A> in Wiring Systems.

Did you complete the repair?</TD>
<TD vAlign=bottom align=middle>

Go to Step21
</TD>
<TD vAlign=center align=middle>

--</TD></TR>
<TR>
<TD vAlign=center align=middle><A name=S16>

16</A></TD>
<TD vAlign=top align=left>

Repair the open or high resistance in the battery positive voltage
circuit of the horn relay switch. Refer to <A
href="http://127.0.0.1:9001/servlets/CellHandler?CellId=62194&RefDoc=644920">Circui t
Testing</A> and <A
href="http://127.0.0.1:9001/servlets/CellHandler?CellId=61965&RefDoc=644920">Wiring
Repairs</A> in Wiring Systems.

Did you complete the repair?</TD>
<TD vAlign=bottom align=middle>

Go to Step21
</TD>
<TD vAlign=center align=middle>

--</TD></TR>
<TR>
<TD vAlign=center align=middle><A name=S17>

17</A></TD>
<TD vAlign=top align=left>

Repair the open or high resistance in the horn control circuit. Refer
to <A
href="http://127.0.0.1:9001/servlets/CellHandler?CellId=62194&RefDoc=644920">Circui t
Testing</A> and <A
href="http://127.0.0.1:9001/servlets/CellHandler?CellId=61965&RefDoc=644920">Wiring
Repairs</A> in Wiring Systems.

Did you complete the repair?</TD>
<TD vAlign=bottom align=middle>

Go to Step21
</TD>
<TD vAlign=center align=middle>

--</TD></TR>
<TR>
<TD vAlign=center align=middle><A name=S18>

18</A></TD>
<TD vAlign=top align=left>

Repair the open or high resistance in the horn ground circuit. Refer to
<A
href="http://127.0.0.1:9001/servlets/CellHandler?CellId=62194&RefDoc=644920">Circui t
Testing</A> and <A
href="http://127.0.0.1:9001/servlets/CellHandler?CellId=61965&RefDoc=644920">Wiring
Repairs</A> in Wiring Systems.

Did you complete the repair?</TD>
<TD vAlign=bottom align=middle>

Go to Step21
</TD>
<TD vAlign=center align=middle>

--</TD></TR>
<TR>
<TD vAlign=center align=middle><A name=S19>

19</A></TD>
<TD vAlign=top align=left>


<H4>Important</H4>

Perform the BCM programming procedure when replacing the
BCM.



Replace the BCM. Refer to <A
href="http://127.0.0.1:9001/servlets/CellHandler?CellId=9004&RefDoc=644920">Body
Control Module Replacement</A> in Body Control System.

Did you complete the replacement?</TD>
<TD vAlign=bottom align=middle>

Go to Step21
</TD>
<TD vAlign=center align=middle>

--</TD></TR>
<TR>
<TD vAlign=center align=middle><A name=S20>

20</A></TD>
<TD vAlign=top align=left>

Replace the horn relay.

Did you complete the replacement?</TD>
<TD vAlign=bottom align=middle>

Go to Step21
</TD>
<TD vAlign=center align=middle>

--</TD></TR>
<TR>
<TD vAlign=center align=middle><A name=S21>

21</A></TD>
<TD vAlign=top align=left>

Operate the horns.

Do the horns operate properly?</TD>
<TD vAlign=bottom align=middle>

System OK</TD>
<TD vAlign=bottom align=middle>

Go to Step1
</TD></TR></TBODY></TABLE>
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<TD align=middle width="50%">Document ID# 644920
2003 HUMMER
H2
</TD>
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