DEFINITION: The diagnostic procedure is used to diagnose the one horn trouble condition in several horn systems.

Did you perform the Diagnostic System Check - Vehicle?

Go to Step 2

Go to Diagnostic System Check - Vehicle

Press the horn switch.

Do all the horns sound?

Go to Testing for Electrical Intermittents

Go to Step 3

1. Disconnect the inoperative horn.
2. Connect a test lamp between the horn control circuit and the good ground.
3. Press and hold the horn button.

Does the test light illuminate?

Go to Step 4

Go to Step 7

1. Connect a test lamp between the control circuit and the horn ground circuit.
2. Press and hold the horn button.

Does the test light illuminate?

Go to Step 5

Go to Step 6

Inspect for poor connection of the inoperative horn. Refer to Testing for Intermittent Conditions and Poor Connections.

Does the test light illuminate?

Go to Step 11

Go to Step 6

1. Connect a 15A fused jumper between the battery positive terminal and the horn control terminal.
2. Connect another jumper between the battery negative terminal and the horn ground terminal.

Does the horn sound?

Go to Step 9

Go to Step 10

Repair poor connection in horn control circuit. Refer to Circuit Testing and Wiring Repairs.

Is the repair complete?

Go to Step 11

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Repair open circuit or poor connection in horn ground circuit. Refer to Circuit Testing and Wiring Repairs.

Is the repair complete?

Go to Step 11

--

9

Repair the high resistance in the horn control circuit or horn ground circuit. Resistance as low as 0.5 ohm can cause trouble to the horn. Refer to Circuit Testing and Wiring Repairs.

Is the repair complete?

Go to Step 11

--

Replace the inoperative horn.

Did you complete the replacement?

Go to Step 11

--

Operate the horn.

Is the horn working normally?

System OK

Go to Step 1