U0158

Code

Generic U — Network/User

Lost Communication With Head Up Display

Brand: Generic

Type: U — Network/User

Views: UK: 35 EN: 68 RU: 28

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Page language: EN

Read all stored DTCs and freeze frame data with a capable scan tool; note other U-codes
Check battery voltage (key on) and charging system status
Inspect HUD power and ground fuses and fusible links
Visually inspect HUD connector and wiring for corrosion, damage, or looseness
Use scan tool to verify whether the HUD module appears on the vehicle network/node list
Measure CAN bus voltages (CANH/CANL) at the HUD connector with key ON

CAN bus idle (recessive): CANH ≈ 2.5 V, CANL ≈ 2.5 V (common-mode)
CAN bus dominant: CANH ≈ 3.5 V, CANL ≈ 1.5 V (differential ≈ 2.0 V)
Typical DC supply to HUD (key ON): approx. vehicle battery voltage ≈ 12–14.5 V
Module ground continuity: low resistance to chassis, typically
Termination resistance between CANH and CANL with network connected: ≈ 60 Ω (two 120 Ω resistors in parallel)
Network data rate: vehicle- and module-specific (commonly 500 kb/s or 250 kb/s); check OEM spec

Record all DTCs and freeze frame data. Note other U-codes or module absence.
Verify battery voltage and charging system. Low battery can prevent module wakeup.
Inspect HUD power, ground, and related fuses. Repair any power/ground faults before communication testing.
With ignition ON, check for HUD presence using a scan tool node list or module query. If the HUD does not appear, proceed to wiring checks.
Visually inspect HUD connectors and harness routing; repair any damage or corrosion.
Measure CANH and CANL voltages at the HUD connector with key ON and engine OFF. Compare to expected idle voltages.
Measure resistance across CANH and CANL (approx. 60 Ω). If open or high, locate open or missing termination.
Check for shorts to battery or ground on each CAN wire (isolate harness sections if necessary).
Wiggle test wiring and connector while monitoring bus traffic; use oscilloscope to look for noise, missing recessive/dominant transitions, or errant voltages.
If wiring and termination are good, attempt software wake/reflash or reinitialize module per OEM procedure. If replacement is required, program/configure the new HUD module as specified.
After repairs, clear codes and road/test to confirm communication is restored and DTC does not return.