B1A88

Code

LAND ROVER B — Body

System Timer

Brand: LAND ROVER

Type: B — Body

Views: UK: 20 EN: 27 RU: 19

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Page language: EN

Causes

Low or unstable battery voltage or poor battery condition
Faulty module internal timer or software/firmware corruption
Intermittent or lost CAN/LIN communication preventing expected heartbeat messages
Open/shorted wiring, poor ground(s) or corroded connectors to the affected module
Incorrect or incomplete module reprogramming or calibration
Blown fuse or faulty power/ignition supply to the module

Symptoms

Vehicle modules not entering sleep or failing to wake properly
Parasitic battery drain or no timer-controlled shutdown of systems
Intermittent functionality of timed features (auto-lock, lighting, accessories)
Warning messages or lamp illumination related to body electronics
Stored or repeating DTCs related to communications (U-codes) or power

What to check

Read all stored/active codes and module freeze frame / event timers with OEM diagnostic tool
Check and record battery state-of-charge and resting voltage (engine off)
Inspect and backprobe module power, ignition feed and ground connections for corrosion or looseness
Scan CAN/LIN bus for errors, lost messages, bus off conditions and check continuity of bus wiring
Verify relevant fuses and relays for the module are present and within specification
Check software/calibration level of the module and consult TSBs for known timer-related issues

Signal parameters

VBATT (engine off, resting): typically 12.4–12.8 V for healthy battery; >11.8 V minimum
Charging system (engine running): 13.5–14.8 V
Module supply/ignition feed: 0 V (off) or near battery voltage when on; check for drop under load
CAN High/Low idle differential: approx. 2.5 V each (CAN_H ~2.5 V, CAN_L ~2.5 V; differential ~0 V idle), active differential ~1–2 V
Heartbeat/periodic message rate: manufacturer dependent (typical 1 Hz to 10 Hz); timeouts often configured in seconds
LIN bus idle: ~12 V or specified reference depending on vehicle; check OEM spec

Diagnostic algorithm

Connect an OEM-level diagnostic tool and retrieve all codes from body and gateway modules; record freeze frame and last occurrence data.
Check battery condition and measure static/resting voltage and voltage during cranking and normal operation; charge or replace battery if marginal.
Inspect and secure power and ground at the affected module(s); repair corroded terminals or damaged wires.
Monitor CAN/LIN traffic while attempting to reproduce the fault; note missing periodic messages or bus errors and trace wiring to nearest junctions.
Verify fuses/relays and ignition feed circuits for continuity and proper operation; repair as required.
If communications and power are good, check module software/calibration level and apply any manufacturer updates or reflash the module per instructions.
Clear codes and perform functional tests (sleep/wake cycle, timed features) to confirm repair. If fault persists and wiring/power/communication are verified, consider module replacement per OEM procedure.
After repair, road test and monitor for recurrence; re-scan for additional codes that may have been masked by the timer fault.

Likely causes

Battery voltage low or intermittent power feed to the module
CAN bus communication errors or missing periodic messages (heartbeat)
Module software fault or need for reflash/reset
Corroded connector or poor ground at the affected body/control module

Fault status

⚠️ Status

System Timer fault detected — timer or timed-communication failure. Check power, ground, communications and module software.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2 hours

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