U0155

Code

Generic U — Network/User

Lost Communication With Instrument Panel Cluster (IPC) Control Module

Brand: Generic

Type: U — Network/User

Views: UK: 59 EN: 179 RU: 92

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Page language: EN

Causes

Faulty IPC (internal failure)
Loss of power or ground to the IPC
Open, shorted, or corroded communications wiring or connectors
Failed or missing network termination (CAN bus)
Other control module causing bus error or bus-off condition
Blown fuse or intermittent supply

Symptoms

Instrument cluster blank, frozen, or unresponsive
No dashboard gauges, backlighting, or cluster messages
Multiple related U-codes for other modules
Warning lights related to communications or cluster functions
Loss of customizable features (clock, trip, settings)
Intermittent operation of cluster functions

What to check

Connect a scan tool and attempt to communicate with IPC; note any additional U-codes and freeze frame data
Check for stored network-related codes in other modules
Inspect IPC connector for corrosion, bent pins, water intrusion, or overheating
Verify IPC power and ground circuits with ignition on and key-off (battery voltage at supply pin, good chassis/ground)
Measure network voltages on CAN_H and CAN_L at the IPC connector with ignition ON
Check resistance across CAN_H and CAN_L with ignition off — should read approx. network termination (~60 ohms for two 120 Ω terminators in parallel)

Signal parameters

CAN bus idle voltage: CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V (recessive state); dominant state example: CAN_H ≈ 3.5 V, CAN_L ≈ 1.5 V
Differential voltage when active: typically ~2.0 V (dominant)
Termination resistance across CAN_H and CAN_L at two terminators: ~60 ohms total
Module supply voltage at IPC battery/ignition feed: approx. 12 V (varies with system state)
Wake and sleep timing/messages on network when key on/off (observed with a capable CAN data logger or scan tool)

Diagnostic algorithm

Record the freeze frame and full list of DTCs from all modules. Note whether only the IPC is affected or multiple modules.
Reproduce the symptom: attempt to communicate with the IPC using a scan tool. Confirm U0155 is current or stored and note conditions (ignition key position, after battery disconnect, etc.).
Inspect IPC connector and harness for damage, corrosion, or loose pins. Repair or reseat connector where required.
Verify power and ground at the IPC connector with a DVOM. Check fuses and relays feeding the IPC; replace if blown or intermittent.
With ignition on, back-probe CAN_H and CAN_L at the IPC connector. Verify expected idle voltages and presence of data using an oscilloscope or scan-tool bus monitor.
Check termination resistance between CAN_H and CAN_L with ignition off. If open or not near expected value (~60 Ω), locate missing or damaged terminator.
Wiggle test wiring from IPC to nearest network junction while observing communication and bus integrity to identify intermittent faults.
If bus is shorted to battery or ground, isolate sections (disconnect IPC and other nodes) and measure to find the shorted segment.
If wiring, connectors, fuses, and grounds test good and the bus is otherwise healthy, attempt reprogramming/ECU wake procedure per manufacturer guidance; update IPC software if available.
If the IPC still does not respond and all inputs are correct, consider replacing the IPC. After replacement, clear codes and verify full network communication and functionality.