Test Description

WARNING: This page is about a different car, the 2007 Hummer H2. However, it is still accessible from the selected car via links, so may be relevant.

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 ohms 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	No
DEFINITION: This diagnostic procedure is for use with systems that have multiple horns in which one of the horns is inoperative.
1	Did you perform the Diagnostic System Check - Vehicle?	Go to Step 2	Go to Diagnostic System Check - Vehicle
2	Depress the horn switch. Do all of the horns operate?	Go to Testing for Intermittent Conditions and Poor Connections	Go to Step 3
3	Disconnect the inoperative horn. Connect a test lamp between the horn control circuit and a good ground. Depress and hold the horn switch. Does the test lamp illuminate?	Go to Step 4	Go to Step 7
4	Connect a test lamp between the horn control circuit and the horn ground circuit. Depress and hold the horn switch. Does the test lamp illuminate?	Go to Step 5	Go to Step 8
5	Inspect for poor connections at the inoperative horn. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition?	Go to Step 11	Go to Step 6
6	Connect a 15-amp fused jumper wire between the positive battery terminal and the control terminal of the horn. Connect another jumper wire between the negative battery terminal and the ground terminal of the horn. Does the horn sound?	Go to Step 9	Go to Step 10
7	Repair the open or poor connection in the horn control circuit. Refer to Circuit Testing and Wiring Repairs . Did you complete the repair?	Go to Step 11	-
8	Repair the open or poor connection in the horn ground circuit. Refer to Circuit Testing and Wiring Repairs . Did you complete the repair?	Go to Step 11	-
9	Repair the high resistance in the horn control circuit or the horn ground circuit of the horn. A resistance as low as 0.5 ohms could cause operating problems with the horn. Refer to Circuit Testing and Wiring Repairs . Did you complete the repair?	Go to Step 11	-
10	Replace the inoperative horn. Refer to Horn Replacement . Did you complete the replacement?	Go to Step 11	-
11	Operate the horns. Do the horns operate properly?	System OK	Go to Step 1