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Home / DTC / U0194 — Lost Communication With Digital Audio Control Module B

U0194 — Lost Communication With Digital Audio Control Module B

Detailed page for trouble code U0194.

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Code

U0194

Generic U — Network/User

Lost Communication With Digital Audio Control Module B

Brand: Generic
Type: U — Network/User
Views: UK: 16 EN: 28 RU: 17
AI status
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Page language: EN

Causes

  • Faulty or disconnected DACM (Digital Audio Control Module B)
  • Open, shorted or high-resistance wiring on CAN/LIN communication circuits
  • Poor power or ground supply to the DACM
  • Blown fuse or relay supplying the module
  • Corroded/damaged connectors or pins
  • Fault in another network module (BCM, gateway, audio head unit) affecting bus traffic

Symptoms

  • No audio or intermittent audio from affected zones
  • Audio-related features (phone, navigation, presets) unavailable or showing errors
  • Infotainment or radio display may show module missing or communication fault
  • One or more related modules report U0194 or other network U-codes
  • Possible warning message or chime related to audio or network

What to check

  • Read all U-codes and freeze frame with a dealer-level scan tool; note related network codes
  • Check battery voltage (should be stable ~12–14 V) and clear low-voltage conditions
  • Inspect fuses and relays that feed the DACM and associated network modules
  • Visually inspect DACM connector and wiring for corrosion, damage, or loose pins
  • Check for physical damage or water intrusion in dash/console areas
  • Verify presence of the DACM on the bus with a scan tool (module list)

Signal parameters

  • CAN High and CAN Low idle voltage: approximately 2.5 V each; differential ~0 V
  • CAN dominant state: CANH ≈ 3.5 V, CANL ≈ 1.5 V (differential ≈ 2.0 V) during activity
  • Typical CAN bus data rates: 500 kbps (high speed) or 250 kbps (mid speed) depending on vehicle
  • Bus termination: approx. 60 ohms measured across CANH–CANL at key harness connector
  • Module supply voltage: battery voltage (approx. 12–14 V) at DACM power pin
  • Module ground: continuity to chassis ground with low ohms (

Diagnostic algorithm

  1. Connect a professional scan tool; read and record all stored and pending U-codes and any related audio or network codes.
  2. Verify vehicle battery voltage and charging system are within spec. Recharge or stabilize battery if low and clear codes; attempt to reproduce.
  3. Check fuses and relays for the audio module and related network nodes; replace if blown and retest.
  4. Inspect the DACM connector and harness for damage, corrosion, bent pins, or water intrusion. Repair or secure connectors as needed.
  5. With ignition on, verify power and ground at the DACM connector (backprobe): module should have battery voltage on supply pin and good chassis ground.
  6. Use a scope or DVOM to measure CANH and CANL at the DACM connector: confirm idle voltages (~2.5 V), differential transitions during bus activity, and proper termination resistance (~60 Ω).
  7. If CAN lines show short to voltage or ground, trace and repair the shorted section of harness; perform wiggle testing while monitoring bus traffic to find intermittent breaks.
  8. Check for other modules on the same bus reporting faults. If the DACM is absent on the module list, attempt re-detection by cycling power, clearing codes, or performing a module scan/initialization procedure.
  9. If wiring and bus are OK but communication is still lost, check for required software updates or module programming. Reflash or reprogram the DACM or gateway per manufacturer procedures.
  10. If the DACM fails to respond after power/ground/wiring and software checks, consider replacing the DACM. After replacement, program/configure the new module and clear codes, then retest for proper communication.

Likely causes

  • Loose or corroded connector at the DACM
  • Damaged CAN high/low wiring near door harness or dash area
  • Module has lost internal power/ground
  • Faulty BCM/gateway not forwarding messages
  • Recent repairs or parts replacement left the module unprogrammed

Fault status

⚠️ Status
Lost Communication With Digital Audio Control Module B — messages from DACM B not being received on the vehicle communication network.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 1.5-3.0 hours

Similar codes

U0100 U0115 U0142 U0155 U0190 U0299
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