B1921

Code

LAND ROVER B — Body

Diagnostic Monitor Stand - High Strength

Brand: LAND ROVER

Type: B — Body

Views: UK: 18 EN: 56 RU: 23

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Page language: EN

Causes

Faulty diagnostic monitor module (internal failure)
Open, short or high-resistance wiring in the monitor circuit
Poor or corroded connector or ground at the module
Intermittent or low battery/charging voltage during self-test
CAN bus or other network communication errors
Water ingress or physical damage to connector/module

Symptoms

Lamp or warning message on instrument cluster related to the affected system
Multiple related DTCs stored or intermittent fault entries
Loss or degraded operation of the system monitored by the diagnostic module
Intermittent faults that change with vibration or temperature
Possible reduced functionality of safety features while fault present

What to check

Read all stored and pending DTCs with a capable scanner; record freeze-frame and related codes
Inspect module and nearby wiring for corrosion, water, damage or rodent chew
Check and clean connectors; confirm connector retention and seals
Measure module supply voltage with key ON — expected ~11–15 V
Verify good battery voltage and charging system health
Check module ground resistance to chassis (low resistance, typically

Signal parameters

Module supply voltage (typical): 11–15 V with key ON
Module ground: near 0 Ω to chassis (expect
CAN bus idle voltages: CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V (recessive); dominant states show ~CAN_H 3.5 V and CAN_L 1.5 V
Expected data traffic present on network during wake (varies by vehicle)
No short to battery or ground on signal lines; wiring continuity typical infinite to open indicates break

Diagnostic algorithm

Retrieve and record all DTCs and freeze-frame data. Note any related modules reporting communication faults.
Visually inspect the diagnostic monitor module, connector boot seals, wiring harness routing and nearby areas for water ingress or damage.
With battery charged, measure module supply and ground at the connector. Repair any low voltage or poor ground before further tests.
Check connector pins for corrosion, bent pins, or poor contact. Unplug, inspect, clean and reseat connector.
Use a scan tool to monitor live data and watch for communication dropouts or unusual values. Reproduce fault if intermittent (road/test or vibration).
If communication suspects exist, use an oscilloscope to verify CAN_H/CAN_L waveforms and differential signal integrity at the module connector.
Perform wiring continuity and resistance checks between module, fuse, and ground; repair damaged wiring or poor crimps as needed.
Clear codes and retest. If fault returns and wiring/power/grounds are good, check for software updates or module reprogramming procedures from dealer/repair information.
If all inputs and communications check good and software is current, consider module replacement as final step according to manufacturer repair procedure.

Likely causes

Corroded or poorly seated connector at the diagnostic monitor
High resistance ground or power feed to the module
Fault on local wiring (short to voltage or open circuit)
Module internal fault or failed components
Network communication fault (CAN bus) causing invalid readings

Fault status

⚠️ Status

Diagnostic Monitor Stand — High Strength. Module/self-test detected abnormal signal or communication integrity issue. Inspect wiring, connectors, power/ground and communications.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-3.0 hours

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