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DTC Test 21 Or 23: Speed Sensor Circuit

WARNING: This page is about a different car, the 1997 Lexus SC 300. However, it is still accessible from the selected car via links, so may be relevant.
  1. Check if cruise control ECU is receiving input signal from speed sensor (instrument cluster). See INPUT SIGNAL CIRCUITS  under CIRCUIT TESTS. If input signal circuit is not okay, go to next step. If input signal circuit is okay:
    • CODE - Replace cruise control ECU.
    • NO CODE - Perform next procedure listed in DIAGNOSIS BY SYMPTOM  table in TROUBLE SHOOTING.
  2. Check speedometer operation. Repair speedometer if it does not operate. See INSTRUMENT PANEL article. If speedometer operates, check wiring harness and connectors for loose connections. Repair wiring harness and connectors if necessary. If wiring harness and connectors are okay, replace cruise control ECU.