B2955 — No Response NM Message (Cluster)

Causes

• Faulty instrument cluster (internal failure)
• Open/short in CAN bus wiring (CAN High/Low)
• Poor battery voltage or intermittently low supply
• Bad ground or corroded connector at the cluster or gateway module
• Blown fuse or loss of cluster power feed
• Module in bus-off state or firmware/software fault

Symptoms

• Instrument cluster blank or partially non-functional
• Warning lights missing or stuck, incorrect gauge readings
• Intermittent or permanent loss of communication with cluster on scan tool
• Other modules report lost communication or related U-codes
• Vehicle may not enter normal ignition/run states or weird wake-up behavior

What to check

• Use a capable scan tool to read all modules and note which module(s) are not present
• Check battery voltage (key ON and cranking) and inspect for recent battery disconnects
• Visually inspect cluster connector and harness for corrosion, damage, or bent pins
• Check fuses and relays for cluster and body control module circuits
• With ignition ON, backprobe CAN High and CAN Low at the cluster connector and verify idle voltages
• Check termination resistance across CAN H-L (expected ≈60 Ω with two 120 Ω terminators in parallel)

Signal parameters

• CAN bus idle voltages (recessive): CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V
• CAN bus dominant state typical voltages: CAN_H ≈ 3.5 V, CAN_L ≈ 1.5 V
• Expected CAN differential when dominant ≈ 2.0 V
• Termination resistance across CAN_H−CAN_L ≈ 60 Ω (two 120 Ω terminators in parallel)
• Common high-speed CAN baud rates: 500 kbps (verify vehicle-specific)
• NM message frequency/IDs vary by model — use factory data or a capable scanner to view expected NM frames

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