Code
C1A80
LAND ROVER
C — Chassis
Control Module Communication Fault
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UK: 3
EN: 5
RU: 3
AI status
Completed
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Causes
- Damaged or corroded wiring harness or connector on the network lines
- Poor or missing module power or ground supply (fused power, battery condition, poor ground)
- Faulty module that is not transmitting or receiving on the network
- Intermittent connector contact (moisture, corrosion, bent pins)
- Short to battery or ground on CAN/LIN wires or a high resistance/opens
- Missing or incorrect module programming or software mismatch after a module replacement or update
Symptoms
- Stored C1A80 DTC in one or more modules and possible related communication fault DTCs
- One or more modules unresponsive to diagnostic scan tool or missing from network topology
- Intermittent or permanent loss of vehicle functions controlled by the affected module (lighting, convenience features, cluster messages, etc.)
- One or more dashboard warnings or illuminated malfunction lamps
- Erratic behavior of systems that rely on messages from the affected module
What to check
- Retrieve all stored DTCs and freeze-frame data with a capable dealer-level or professional scan tool; record module IDs that report C1A80
- Check battery voltage (key on and engine off) and main battery condition; verify good battery connections
- Visually inspect connectors and wiring at the affected module(s) and gateway for corrosion, water entry, damage, or bent pins
- Confirm the module appears on the network with the scan tool (module present/responding) and note which networks (CAN high-speed, medium-speed, LIN) are affected
- Check for other communication codes (U-codes) that identify the network or gateway involved
- Measure CANH/CANL or LIN signals with a scope or DMM as appropriate and check termination resistance across the bus (~60 Ω for two 120 Ω terminators)
Signal parameters
- Typical CAN idle (recessive): CANH ≈ 2.5 V, CANL ≈ 2.5 V (common-mode)
- Typical CAN dominant bit: CANH ≈ 3.5 V, CANL ≈ 1.5 V (differential ≈ 2 V)
- Termination: ≈60 Ω measured across CANH–CANL (two 120 Ω terminators in parallel)
- Bus bit-rates commonly encountered: 125 kbps (body/low-speed), 250 kbps, 500 kbps (powertrain) — confirm expected bitrate for the affected network
- LIN idle: single-wire referenced to ground; bus typically near battery voltage when idle on some implementations — check manufacturer data for exact values
Diagnostic algorithm
- Gather information: note when the fault was first seen, any recent battery disconnects, module replacements, software updates, or aftermarket installs.
- Scan: connect a professional scan tool and read all modules; record C1A80 occurrence, related DTCs, and module addressing/IDs. Use topology or network view if available to see which modules are missing.
- Battery & power: verify battery state-of-charge and voltage (>12.4 V resting preferred), check main fuses and fusable links supplying the affected module, verify ground connections for corrosion/tightness.
- Visual inspect: inspect pins and wiring at the reported module(s), connector N/A seals, and any splice points or gateways between networks for corrosion, water ingress, or physical damage.
- Passive electrical checks: with ignition on, measure CANH/CANL voltages relative to ground; check termination resistance across CANH–CANL (~60 Ω). Look for shorts to battery or ground.
- Active checks: use a scope to view CAN/LIN waveforms while exercising network traffic; verify expected message activity and clean signal edges. Compare against a known-good vehicle or manufacturer waveforms if available.
- Isolate: disconnect suspected modules (after following safe procedures) and re-test bus behavior; remove aftermarket devices if present.
- Repair/replace: repair wiring/connectors as needed. If wiring and power/grounds are good and the module is the only non-communicating device, consider reflashing or replacing the module per manufacturer procedure.
- Re-test: clear codes, perform network diagnostics and road test (or exercised functions) to confirm the fault does not return. If fault is intermittent, monitor with data logger over time.
- Escalate: if multiple modules/gateways fail or network-level faults persist, consult manufacturer wiring diagrams, data communication schematics, and technical service bulletins for model-specific guidance.
Likely causes
- Loose/corroded connector at the affected module or gateway
- Open or shorted CAN/LIN wiring between module and network gateway
- Weak vehicle battery or poor main ground affecting module startup and bus communications
- Failed module (internal communications transceiver)
- Incorrect or incomplete software calibration after recent module replacement
Fault status
Status
C1A80 — Control Module Communication Fault: A control module has reported loss/corruption of network communication. Inspect power, ground, connectors and network wiring; verify module presence on the bus before replacing modules.
Repair difficulty: Medium
Diagnostic time: 1.0-3.0 hours
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