What does it mean?
B1474 is a Body (airbags, seat belts, body electronics) fault code. It indicates: Channel 5 Audio Speaker Output Circuit Performance .
Symptoms
- Sound from the channel 5 position is distorted, thin, buzzing or rattling
- Level from that speaker rises and falls on its own
- Fader and balance no longer place the sound where they should
- The amplifier mutes the channel for a while and then restores it
- Code returns after clearing even though the speaker still makes some sound
Likely causes
- Voice coil partly damaged or aged, so the impedance has drifted out of the expected window
- Replacement or added speaker with the wrong impedance on that channel
- High-resistance joint at a corroded terminal or a poor crimp from an earlier installation
- Conductor breaking down where the loom flexes, giving a load that appears and disappears
- Moisture in the speaker basket or connector after a leaking seal or a torn door membrane
- Amplifier output stage for channel 5 losing performance
How to fix it
- Use a steady tone with fader and balance to identify the affected speaker by ear
- Remove the trim and inspect the cone, surround and terminals for damage, corrosion and moisture
- Measure the DC resistance at the speaker terminals and compare with the value for this system
- Repeat at the amplifier connector; a large difference means the fault lies in the wiring between
- Flex the loom at every bend point while watching the meter or listening for the dropout
- Connect a known-good speaker at the amplifier end to prove whether the output itself is clean
- Repair the harness or fit a correct-specification speaker, then clear the code and verify with a fader sweep
- Consider the amplifier only after the speaker and the wiring both test correct