C1743: Rear Sounder Short to Battery
The C1743 code indicates that the control module has detected a short circuit between the rear sounder circuit and the battery voltage line. The rear sounder, also known as an alarm siren, is part of the vehicle's security system and emits audible alerts. A short to battery voltage means the sounder circuit is receiving constant or unexpected battery power, preventing proper operation or causing continuous activation. The security system control module monitors resistance and voltage in this circuit to detect electrical faults.
1. Commonly Affected Makes
2. Most Common Causes
- Damaged wiring insulation in the rear sounder circuit causing a short to battery positive
- Rear sounder connector with bent pins, corrosion, or water intrusion
- Internal failure of the rear sounder module (coil or internal electronics shorted)
- Faulty alarm control module (BCM or security module) with a failed output driver
- Aftermarket modifications or installations interfering with the original circuit
3. Symptoms You Will Notice
- Alarm siren sounding continuously or intermittently
- No sound from the alarm when triggered
- Security system malfunction or warning light on the dashboard
4. Step-by-Step Diagnosis
Visually inspect the rear sounder wiring and connector for damage, corrosion, or water intrusion
Disconnect the rear sounder and check for battery voltage on the sounder circuit using a multimeter
Test the rear sounder module for internal shorts by measuring resistance across its terminals
Check the alarm control module for proper output signals and grounds
If aftermarket equipment is present, verify it is not interfering with the original circuit
5. Frequently Asked Questions
Is it safe to drive?▼
Yes, it is generally safe to drive, but the security system may not function correctly, and the alarm may sound unexpectedly. It is recommended to have the issue diagnosed and repaired promptly.
How much does it cost to fix?▼
Repair costs typically range from $100 to $400, depending on the cause. Simple wiring repairs may cost around $100-$200, while replacing the sounder module or control module can be $200-$400 or more.