High Speed CAN Communication Bus (+) Low
2014-2016 Chevrolet Spark EV Electric Motor
Description
The CAN High wire voltage is lower than expected, indicating a short to ground or excessive load on the bus.
Symptoms
- Communication failures
- Multiple DTCs from various modules
- Intermittent system operation
Common Causes
- CAN H wire shorted to ground
- Module pulling CAN H low
- Damaged wiring insulation
- Water intrusion in connector
Diagnostic Steps
- Measure CAN H voltage
- Disconnect modules one at a time to find short source
- Inspect wiring for chafing against ground
- Check connectors for moisture
Repair Notes
Find and repair the short to ground on the CAN H wire. Inspect for damaged insulation.
Related Codes
Other Network Codes
- U0001High Speed CAN Communication Bus
- U0002High Speed CAN Communication Bus Performance
- U0003High Speed CAN Communication Bus (+) Open
- U0005High Speed CAN Communication Bus (+) High
- U0006High Speed CAN Communication Bus (-) Open
- U0007High Speed CAN Communication Bus (-) Low
- U0008High Speed CAN Communication Bus (-) High
- U0009High Speed CAN Communication Bus Shorted Together
- U0010Medium Speed CAN Communication Bus
- U0028Vehicle Communication Bus A Performance
U0004 on Other Vehicles
Chevrolet Astro
1995-2005 4.3L V6 Vortec
Chevrolet Avalanche
2002-2006 5.3L V8 Vortec
Chevrolet Avalanche
2002-2006 8.1L V8 Vortec
Chevrolet Avalanche
2007-2013 5.3L V8 Vortec
Chevrolet Avalanche
2007-2013 6.0L V8 Vortec
Chevrolet Aveo
2012-2018 1.6L I4
Chevrolet Beat
2018-2021 1.2L I4
Chevrolet Beretta
1990-1996 2.2L I4
Common Questions
What does code U0004 mean on a 2014-2016 Chevrolet Spark EV?
U0004 stands for "High Speed CAN Communication Bus (+) Low". The CAN High wire voltage is lower than expected, indicating a short to ground or excessive load on the bus.
What are the symptoms of U0004 on a Chevrolet Spark EV?
Common symptoms of U0004 include: Communication failures, Multiple DTCs from various modules, Intermittent system operation.
What causes U0004 on a 2014-2016 Chevrolet Spark EV?
Common causes of U0004 include: CAN H wire shorted to ground, Module pulling CAN H low, Damaged wiring insulation, Water intrusion in connector.