B102F

Code

LAND ROVER B — Body

Auxiliary switch

Brand: LAND ROVER

Type: B — Body

Views: UK: 12 EN: 19 RU: 15

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Open or shorted wiring to the auxiliary switch
Poor or corroded connector or pin(s) at the switch or control module
Failed auxiliary switch (mechanical or internal electrical fault)
Faulty body/control module input circuit
Water ingress, dirt or physical damage to switch or harness
Intermittent connection due to vibration or chafing

Symptoms

Associated auxiliary function does not operate (depends on fitted auxiliary switch function)
Intermittent or no response from the auxiliary switch
Warning light or message may be present in vehicle display
Stored B102F fault present in module memory

What to check

Read and record DTC(s) and freeze frame data with a compatible diagnostic tool
Visually inspect switch, surrounding area and wiring for damage, corrosion, loose connectors or signs of water ingress
Operate the auxiliary switch while observing data stream or while monitoring the circuit with a multimeter/oscilloscope
Back-probe the switch connector and measure reference supply, signal voltage and continuity to the module
Check ground integrity for related circuits at the module and chassis

Signal parameters

Reference voltage to switch: approximately battery voltage (~11–14 V) when switched to supply (vehicle off/on conditions may vary)
Signal voltage when switch closed: near 0 V (ground) or near battery voltage depending on circuit design (check factory wiring)
Resistance across switch terminals: near 0 Ω when closed, infinite/very high when open (measure with switch disconnected)
Intermittent changes in signal when wiggling harness indicate poor connection

Diagnostic algorithm

Connect diagnostic scan tool, read and record stored codes and freeze frame/fault occurrence data
Attempt to operate the auxiliary switch and watch live data or the related channel to confirm fault reproduction
Visually inspect switch and harness for damage, corrosion, signs of water ingress or mechanical wear
With ignition off, disconnect the switch connector and inspect pins for corrosion, bending, or pushed-out pins; clean and repair as needed
Measure continuity between the switch connector and the control module connector; check for short to ground or battery on the signal wire
Back-probe the connector with ignition on and operate switch; verify reference supply and signal voltage levels match expected values (consult vehicle wiring if available)
If wiring and connectors check good, bench-test or replace the auxiliary switch and re-test circuit
If fault persists after verifying and repairing switch and wiring, consider diagnostic of body/control module input (check for module power/ground, update software if applicable)
Clear codes and road-test to confirm repair; monitor for return of B102F before declaring repair complete

Likely causes

Damaged wiring harness (chafed, pinched or broken) between the switch and module
Corroded connector terminals at the auxiliary switch or module
Failed auxiliary switch contacts or internal electronics
Short to ground or short to battery on the switch feed or signal circuit

Fault status

⚠️ Status

Auxiliary switch circuit fault reported by body/control module — signal out of expected range (open, short, intermittent or invalid voltage).

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5 - 2.0 hours

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