Circuit Description
The body control module (BCM) controls the horn relay by grounding the control circuit of the horn relay coil. When the horn relay coil is grounded, the horn relay contacts close, applying voltage to the horn via the horn supply voltage circuit.
DTC Descriptor
This diagnostic procedure supports the following DTC:
DTC B2750 Horn Relay Coil Circuit
Conditions for Running the DTC
The BCM monitors the voltage level on the horn relay control circuit whenever the ignition is in the RUN position.
Conditions for Setting the DTC
The BCM will set DTC B2750 as current whenever an improper voltage level is detected on the horn relay control circuit, for more than 15 seconds.
Action Taken When the DTC Sets
The BCM will disable the driver for the horn relay control circuit whenever DTC B2750 is set as current.
Conditions for Clearing the MIL/DTC
DTC B2750 will clear when an improper voltage level is no longer detected on the horn relay control circuit, or when you use a scan tool to clear DTCs.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
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Listen for an audible click when the horn relay operates. Command both the ON and OFF states. Repeat the commands as necessary.
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Tests for voltage at the coil side of the horn relay. The horn fuse supplies power to the coil side of the horn relay.
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Verifies that the BCM is providing ground to the horn relay.
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Tests if ground is constantly being applied to the horn relay.
Step | Action | Yes | No |
|---|---|---|---|
Schematic Reference: Horn Schematics Connector End View Reference: Horn Connector End Views | |||
1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | |
Does the horn relay turn ON and OFF with each command? | Go to Diagnostic Aids | Go to Step 3 | |
Does the test lamp illuminate? | Go to Step 4 | Go to Step 10 | |
Does the test lamp turn ON and OFF with each command? | Go to Step 8 | Go to Step 5 | |
Does the test lamp remain illuminated with each command? | Go to Step 7 | Go to Step 6 | |
6 | Test the control circuit of the horn relay for a short to voltage or an open. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 13 | Go to Step 9 |
7 | Test the control circuit of the horn relay for a short to ground. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 13 | Go to Step 9 |
8 | Inspect for poor connections at the horn relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 13 | Go to Step 11 |
9 | Inspect for poor connections at the harness connector of the body control module (BCM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition? | Go to Step 13 | Go to Step 12 |
10 | Repair the battery positive voltage circuit of the horn relay. Refer to Wiring Repairs . Did you complete the repair? | Go to Step 13 | -- |
11 | Replace the horn relay. Did you complete the replacement? | Go to Step 13 | -- |
12 | Replace the BCM. Refer to Control Module References for replacement, setup, and programming. Did you complete the replacement? | Go to Step 13 | -- |
13 |
Does the DTC reset? | Go to Step 2 | System OK |
