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Home / DTC / B1246 — Failure in the circuit of the panel potentiometer switch of weak light

B1246 — Failure in the circuit of the panel potentiometer switch of weak light

Detailed page for trouble code B1246.

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Code

B1246

LAND ROVER B — Body

Failure in the circuit of the panel potentiometer switch of weak light

Brand: LAND ROVER
Type: B — Body
Views: UK: 4 EN: 13 RU: 7
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Page language: EN

Causes

  • Broken, chafed or pinched wiring in the potentiometer/dimmer circuit
  • Corroded, loose or damaged connector at the potentiometer or body control module (BCM)
  • Failed panel potentiometer or dimmer switch (internal open/short or poor wiper contact)
  • Blown fuse or poor power/ground to the potentiometer circuit
  • Faulty BCM/instrument cluster input stage or intermittent module communication
  • Water ingress or contamination at switch or connector causing intermittent contact

Symptoms

  • Instrument cluster backlighting not adjustable or stuck at one brightness (usually dim or inoperative)
  • Lighting may be permanently bright or permanently dim; brightness levels do not respond to dimmer knob
  • Intermittent operation of panel illumination (works only when tapping or moving switch)
  • Related interior lights may be affected; stored B1246 fault in fault memory

What to check

  • Read and record the fault code with an OEM-level scan tool; note freeze frame and occurrence count
  • Visually inspect the dimmer switch/potentiometer, harness and connector for damage, corrosion or water ingress
  • Check related fuses and relays for the instrument/console lighting circuit
  • Backprobe the potentiometer connector and measure supply, ground and wiper signal while operating the dimmer
  • Wiggle test wiring and connector while observing the wiper voltage and scan tool live data for dropouts
  • Measure resistance of the potentiometer across outer terminals and between wiper and an end terminal while rotating knob to verify smooth change

Signal parameters

  • Reference/supply voltage to potentiometer: typically ~5 V key-on (may be vehicle-specific)
  • Wiper output voltage: should vary smoothly across approx. 0–5 V (or 0.5–4.5 V depending on vehicle) as dimmer is rotated
  • Potentiometer total resistance: typically in the low kilo-ohm range (commonly 1 kΩ–10 kΩ) and should change smoothly without jumps
  • Open-circuit = infinite resistance; short to ground or supply will show ~0 V or reference voltage respectively

Diagnostic algorithm

  1. Connect OEM scan tool, retrieve B1246 and related codes; record freeze frame and live data for illumination/dimmer input.
  2. Visually inspect dimmer switch, dashboard wiring and connectors for visible damage, corrosion or moisture. Repair any obvious issues.
  3. Verify fuses and supply to the dimmer circuit. Replace blown fuses and retest.
  4. Backprobe the potentiometer connector: with ignition ON measure reference supply voltage, ground continuity, and wiper voltage while rotating the knob. Compare to expected signal parameters.
  5. With switch disconnected, measure potentiometer resistance across end terminals and between wiper and ends while moving the knob — resistance should vary smoothly without sudden jumps or open readings.
  6. If wiper signal is erratic or open/short present, replace the potentiometer/dimmer switch and retest.
  7. If potentiometer bench-tests good, trace wiring between potentiometer and BCM for opens/shorts; repair damaged wiring or connectors. Use continuity and resistance checks, repair splices as needed.
  8. If wiring and switch are good but fault persists, inspect BCM/instrument cluster input for damage. Consider module diagnostics or replacement only after all wiring and switch checks are complete.
  9. Clear codes and verify the fault does not return after functional test and road or ignition cycles.

Likely causes

  • Worn or dirty potentiometer wiper (age/wear)
  • Corroded connector at the dash dimmer switch
  • Open or shorted wiring between the potentiometer and the BCM/instrument cluster
  • Poor ground at instrument panel harness

Fault status

⚠️ Status
Panel potentiometer/dimmer circuit fault detected (instrument panel illumination control) — check dimmer switch, wiring and module input.
🟡 Repair difficulty: Medium
⏱️ Diagnostic time: 0.5-1.5 hours

Similar codes

B1240 B1241 B1242 B1243 B1244 B1245
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