OBD II scan tool (excluding Hand-held Tester):

WARNING: This page is about a different car, the 2004 Lexus ES 330. However, it is still accessible from the selected car via links, so may be relevant.

INSPECT ECM
1. Turn the ignition switch to ON.
2. Measure the voltage between the specified terminals of the E8 and E10 ECM connectors.
  Standard:
  
  Fig 1: ECM Connector Terminals Specified Condition Chart
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  Fig 2: Identifying ECM Connector Terminals
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
OK: REPLACE ECM (See ECM (3MZ-FE) )

NG: GO TO NEXT STEP.
INSPECT PARK/NEUTRAL POSITION SWITCH ASSY (See DTC I P0705 I TRANSMISSION RANGE SENSOR CIRCUIT MALFUNCTION (PRNDL INPUT) )
NG: REPLACE PARK/NEUTRAL POSITION SWITCH ASSY (See PARK/NEUTRAL POSITION SWITCH ASSY (U151E) ) (GO TO STEP 3 AFTER THE REPLACEMENT)

OK: GO TO NEXT STEP.
INSPECT ECM
1. Turn the ignition switch to ON.
2. Measure the voltage between the specified terminals of the E8 and E10 ECM connectors.
  Standard:
  
  Fig 3: ECM Connector Terminals Specified Condition Chart
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  Fig 4: Identifying ECM Connector Terminals
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
OK: SYSTEM OK

NG: GO TO NEXT STEP.
INSPECT IGNITION OR STARTER SWITCH ASSY
1. Check for continuity between the connector terminals shown in the chart below.
  Standard:
  
  Fig 5: Starter Switch Terminals Continuity Chart
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  Fig 6: Identifying Starter Switch Terminals
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
NG: REPLACE IGNITION OR STARTER SWITCH ASSY (GO TO STEP 5 AFTER THE REPLACEMENT)

OK: GO TO NEXT STEP.
INSPECT ECM
1. Turn the ignition switch to ON.
2. Measure the voltage between the specified terminals of the E8 and E10 ECM connectors.
  Standard:
  
  Fig 7: ECM Terminals Specified Condition Chart
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
  
  Fig 8: Identifying ECM Connectors
  Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
OK: SYSTEM OK

NG: GO TO NEXT STEP.

REPAIR OR REPLACE HARNESS OR CONNECTOR