What does it mean?
U1006 is a Network (CAN bus, module communications) fault code. It indicates: DIS Low Voltage Detected .
Symptoms
- Audio and display shut down or restart during cranking and shortly after start-up
- Radio presets, clock and settings lost after standing overnight
- Dim interior lighting and slow cranking alongside the audio complaint
- Multiple low voltage or communication codes stored in several modules at once
- Sound cuts out at high volume when electrical load is high
- Battery warning lamp on in some cases
Likely causes
- Weak, sulphated or discharged battery that cannot hold voltage under load
- Charging system underperforming because of a worn alternator, slipping belt or failed regulator
- Heavy voltage drop across corroded battery terminals or a loose earth strap
- High resistance in the supply circuit to the audio system, such as a corroded fuse holder or splice
- Parasitic drain flattening the battery overnight so voltage is low at start-up
- Extended accessory use with the engine off, for example running the system on the parked vehicle
- Poor ground for the head unit or amplifier raising the effective voltage drop
How to fix it
- Test the battery with a proper conductance or load test and check its state of charge before anything else
- Measure charging voltage at idle and at raised RPM with lights and blower on, and compare with the specification
- Clean and tighten the battery terminals and the main earth strap, then repeat a voltage drop test on both
- Check the audio supply fuse holder and any splice for corrosion and high resistance
- Perform a parasitic drain test if the battery goes flat when parked
- Read the low voltage value stored in freeze frame data to see how far the voltage fell
- Charge the battery fully, clear the code and see whether it returns before replacing any audio module
- Repair grounds and supply wiring as found; the audio module itself is rarely at fault with this code