Horns Malfunction - Suzuki XL7 2007 Service Manual

9C-43 Instrumentation / Driver Info. / Horn:

Horns Malfunction

Diagnostic Instructions
• Perform the "Diagnostic System Check - Vehicle Diagnostic Information: " prior to using this diagnostic procedure.
• Review "Strategy Based Diagnosis: " for an overview of the diagnostic approach.
• "Diagnostic Procedure Instructions - Vehicle Diagnostic Information: ".
Diagnostic Fault Information
Circuit
Horn Relay Control
Horn Control
Horn Switch Ground
Horn Ground
1. Horn Always On
2. Horn Inoperative
Circuit/System Description
Battery positive voltage is applied at all times to the horn
relay coil and the horn relay switch. Pressing the horn
switch applies ground through the switch contacts and
the horn relay control circuit to the coil side of the relay,
energizing the relay. Battery voltage is then applied
through the switch side of the relay, the horn fuse, and
the horn control circuit to the horns. The body control
module (BCM) may also apply ground to the horn relay
control circuit as described above. The horns sound as
long as ground is applied to the horn relay control circuit.
Diagnostic Aids
If diagnosing a Horn - Poor Tone condition, inspect the
following:
• Debris or water in the horn assembly.
• Proper horn mounting hardware torque. Refer to
"Fastener Tightening Specifications - Horns".
• Debris in the joint where the horns attach to the
vehicle.
Reference Information
Schematic Reference
"Horn Schematics"
Connector End View Reference
"Horn Connector End Views"
Description and Operation
"Horns System Description and Operation"
Electrical Information Reference
• "Circuit Testing: "
• "Connector Repairs: "
• "Testing for Intermittent Conditions and Poor
Connections: "
• "Wiring Repairs: "
Scan Tool Reference
• "Scan Tool Data Definitions - Horns"
• "Scan Tool Data List - Horns"
• "Scan Tool Output Controls - Horns"
Short to Open/High
Ground Resistance
B2750 00 B2750 00
2 2
— 2
— 2
Circuit/System Verification
1. Ignition OFF, connect a test lamp between the horn
fuse test point and ground.
2. Press and release the horn switch. The test lamp
should turn ON and OFF when changing between
the commanded states.
➢ If the test lamp does not illuminate or remains
illuminated at all times, refer to Horn Switch Circuit
Test.
3. Ignition ON, command the horn ON and OFF with a
scan tool. The test lamp should turn ON and OFF
when changing between the commanded states.
➢ If the test lamp does not illuminate, test the control
circuit terminal 18 at the BCM for a short to voltage
or an open/high resistance. If the circuit tests
normal, replace the BCM.
4. Connect a 15A fused jumper wire between the horn
fused test point and B+. The horn should sound and
emit a clear and even tone.
➢ If the horn does not sound, refer to Horn Circuit
Test.
➢ If the sound emitted is not clear and even, refer to
Horn - Poor Tone.
Circuit/System Testing
Horn Switch Circuit Test
1. Disconnect the harness connector C2 at the
underhood fuse block.
2. Connect a test lamp between the control circuit
terminal 27 and B+.
3. Press and release the horn switch. The test lamp
should turn ON and OFF when changing between
the commanded states.
➢ If the test lamp is always ON, test the control circuit
for a short to ground or a sticking horn switch. If the
circuit tests normal, replace the BCM.
➢ If the test lamp is always OFF, test the control
circuit for a short to voltage, an open high
resistance, or a horn switch which is not closing.
Signal
Short to Voltage
Performance
B2750 00
1
2
2
—
—
—
—