Network
generic or reserved
U3004
Accessory Power Relay
Fault on the accessory power relay that switches power to comfort/accessory loads (radio, infotainment, etc.) when the key is in ACC position.
SystemNetwork
Typegeneric or reserved
GroupU3
Range / number– / 04
Possible causes
- Relay contacts failed or coil open high
- Gateway module routing CAN messages incorrectly low
- CAN terminating resistor (120 Ω) drifted out of spec low
Symptoms
- Multiple warning lights may illuminate
- Affected modules may go into limp mode or shut down
- Specific functions inoperative depending on module
- Diagnostic tools may show communication faults
Inspection / repair
- Difficulty: easy
- DIY: possible
- Estimated cost: 20–200 €
- Estimated time: 0.3–1.5 h
- Component: accessory power relay
- Component: relay wiring
- MIL / check engine light
Sources
References
sae:J2012