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DTC B1421/21: SOLAR SENSOR CIRCUIT Lexus RX I

Note. If testing is done in a dark area, DTC may set even though system is normal. Shine a bright light at solar sensor and recheck for DTC.

  1. Remove A/C ECU (instrument cluster ECU), leaving harness connectors connected. Turn ignition on.
  2. Measure voltage (backprobe) between A/C ECU connector terminals C13-15 (Yellow/Black wire) and C13-16 (Blue wire). (Схема №3)or (Схема №4). See «SOLAR SENSOR CIRCUIT VOLTAGE SPECIFICATIONS»(ref-98896-S15703038292001060500000) table.
  3. If voltage is as specified, temporarily substitute a known-good A/C ECU, then retest system. If voltage is not as specified, test solar sensor. See «SOLAR SENSOR»(ref-98896-S23232796292001060500000) under COMPONENT TESTS. Replace sensor as necessary. If sensor is okay, go to next step.
  4. Inspect wiring harness and connectors between sensor and A/C ECU. See «WIRING DIAGRAMS»(ref-98896-S06345939912001060500000). Repair as necessary. If wiring harness and connectors are okay, temporarily substitute a known-good A/C ECU, then retest system.
Condition(1) Volts
Sensor Subjected To Bright Light0.8-4.3
Sensor Covered By ClothLess Than 0.8
(1) As light intensity decreases, voltage should increase.
(1)As light intensity decreases, voltage should increase.

SOLAR SENSOR CIRCUIT VOLTAGE SPECIFICATIONS