Pinpoint Test E: No Horn Output During Alarm Activation
Anti-Theft
Pinpoint Test E: No Horn Output During Alarm Activation
Normal Operation
The Body Control Module (BCM) receives voltage for the anti-theft alarm horn from the Battery Junction Box (BJB) fuse 6 (30A). When the perimeter alarm is activated, the BCM cycles voltage on and off to the anti-theft horn causing the horn output to cycle in conjunction with the turn signals flashing. The horn is case grounded.
NOTE: The traffic horn does not sound during a perimeter alarm event.
This pinpoint test is intended to diagnose the following:
- Wiring, terminals or connectors
- Anti-theft alarm horn
- BCM
PINPOINT TEST E: NO HORN OUTPUT DURING ALARM ACTIVATION
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E1 CHECK THE POWER DOOR LOCK OPERATION
- Press the door lock control switch twice.
- Do the doors lock and unlock?
Yes
GO to E2.
No
REFER to Handles, Locks, Latches and Entry Systems Testing and Inspection to diagnose the power door locks.
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E2 CHECK FOR VOLTAGE TO THE ANTI-THEFT HORN
- Disconnect: Anti-Theft Alarm Horn C4380.
- Enter the following diagnostic mode on the scan tool: BCM DataLogger.
- Measure the voltage between the anti-theft alarm horn C4380-1, circuit CRT02 (GY/VT), harness side and ground while active commanding the BCM PID (ANTITHFT_HRN) on.
- Is the voltage momentarily greater than 10 volts?
Yes
INSTALL a new anti-theft alarm horn. REFER to Anti-Theft Alarm Horn - 4-Door Sedan 4-Door Sedan or Anti-Theft Alarm Horn - 5-Door Hatchback 5-Door Hatchback. TEST the system for normal operation.
No
GO to E3.
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E3 CHECK THE ANTI-THEFT HORN OUTPUT CIRCUIT FOR AN OPEN OR SHORT TO GROUND
- Ignition OFF.
- Disconnect: BCM C2280C.
- Measure the resistance between the anti-theft alarm horn C4380-1, circuit CRT02 (GY/VT), harness side and the BCM C2280C-8, circuit CRT02 (GY/VT), harness side; and between the anti-theft alarm horn C4380-1, circuit CRT02 (GY/VT), harness side and ground.
- Is the resistance less than 5 ohms between the anti-theft alarm horn and the BCM, and greater than 10,000 ohms between the anti-theft alarm horn and ground?
Yes
GO to E4.
No
REPAIR circuit CRT02 (GY/VT) for an open or short to ground. TEST the system for normal operation.
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E4 CHECK FOR CORRECT BCM OPERATION
- Disconnect all the BCM connectors.
- Check for:
- corrosion
- damaged pins
- pushed-out pins
- Connect all the BCM connectors and make sure they seat correctly.
- Operate the system and verify the concern is still present.
- Is the concern still present?
Yes
INSTALL a new BCM. REFER to Multifunction Electronic Modules Body Control Module (BCM). TEST the system for normal operation.
No
The system is operating correctly at this time. The concern may have been caused by a loose or corroded connector.
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