Network
generic / SAE
U0074
Control Module Communication Bus "B" Off
A control module has shut its bus B interface off because the bus is non-functional. Bus B is typically a secondary CAN segment (often body or chassis) and a failure disables all modules connected to it.
SystemNetwork
Typegeneric / SAE
GroupU0
Range / number– / 74
Possible causes
- Bus B line shorted to supply or ground high
- One failing module pulling the bus down medium
- Gateway module routing CAN messages incorrectly 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: hard
- DIY: shop recommended
- Estimated cost: 80–1500 €
- Estimated time: 1–8 h
- Component: can bus wiring
- Component: can terminating resistor
- Component: control module
- MIL / check engine light
- limp mode possible
Sources
References
sae:J2012
iso:11898