U008B

Code

Generic U — Network/User

Vehicle Communication Bus G (+) Open

Brand: Generic

Type: U — Network/User

Views: UK: 21 EN: 26 RU: 27

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Page language: EN

Malfunction indicator lamps for communications (may vary by vehicle)
Loss of features controlled by modules on Bus G (e.g., cluster, body, infotainment — vehicle-specific)
Multiple modules report communication errors or go into limp mode
Stored U008B and possibly other U-codes related to lost communication

Retrieve freeze frame and full list of current/pending U-codes with a capable scan tool
Identify all modules connected to Bus G and note which modules report loss of communication
Visually inspect Bus G wiring, harnesses, and connectors for damage, corrosion, disconnections, or recent service work
Check fuses and power/ground circuits for modules on Bus G
Using scan tool, verify whether some modules still respond — helps locate the break area
Wiggle test connectors and harnesses while monitoring bus communication for changes (engine off / safe conditions)

Expected idle voltages (typical CAN-like bus): Bus G (+) ≈ 2.5–3.5 V relative to chassis ground when recessive; Bus G (−) ≈ 1.0–2.5 V (vehicle-dependent)
Differential voltage (Bus+ minus Bus−) ≈ 1.5–2.5 V when active; near 0 V if both lines shorted
Open-circuit indication: Bus G (+) may float or read near undefined voltage or battery voltage depending on pull-ups and internal module transceivers
DC continuity: low ohms (

Confirm U008B is current and note freeze-frame data and occurrence counts
Scan all modules for related U-codes to determine which modules see the bus and which do not
Visually inspect the full length of the Bus G harness and all related connectors, junction blocks, and modules for damage, corrosion, or recent service marks
Check power and ground for modules on Bus G; a module with lost power/ground can present as a bus open
With ignition ON (as required), measure Bus G (+) voltage at multiple points: at available module connectors, junctions, and near the ECU. Compare to Bus G (−) if applicable
If voltage is missing at a connector, disconnect the connector and check for continuity to the next junction and to the suspected break location; use backprobe pins only where safe and recommended
Perform resistance/continuity testing between terminal pins along the bus to find an open section. Repair any open wiring (splice, replace harness section, repair terminal)
Inspect and, if necessary, clean/repair corroded terminals and connector pins. Securely reseat connectors.
If wiring and connectors check good, isolate suspected modules by disconnecting them one at a time (follow vehicle-specific procedures) to see if the open condition clears, indicating a module transceiver fault
After repairs, clear codes, perform a full system scan, and road/test as required to confirm communication is restored and codes do not return

Open or high-resistance splice/connector on Bus G (+)
Damaged wiring (chafe, pinched, cut) near harness routing or service panels
Intermittent connector contact (corrosion, bent terminal) at a module or junction
Failed module transceiver that pulls the line open