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LS400 Theft Deterrent Starter Cut System Circuit Test

  1. If starter does not operate even after theft system has been deactivated, use key to turn front door lock to unlock position. Recheck starter operation. If starter still does not operate, go to next step.
  2. Disconnect theft deterrent ECU connectors. ECU is located under left side of dash, above junction block No. 1. Ensure shift lever is in Neutral. Turn ignition switch to START position. Using a DVOM, check for battery voltage between ECU connector harness terminal A1 and ground. See Figure.
  3. If battery voltage is present, replace theft deterrent ECU, and retest system. If battery voltage is not present, repair short or open between ECU harness connector terminal A1 and the starter relay. Refer to STARTER RELAY  under RELAYS. Also, refer to NEUTRAL START SWITCH  under ENGINE SENSORS & SWITCHES.
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