Inspection Procedure

WARNING: This page is about a different car, the 2002 Toyota Prius. However, it is still accessible from the selected car via links, so may be relevant.

Check voltage between terminals TAM and E2 of ECM connector.

Fig 1: Locating ECM Terminals TAM & E2
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

PREPARATION
1. Remove ECM with connectors still connected.
2. Turn ignition switch ON.
  NOTE: As the temperature increases, the voltage decreases.
  
  Check: voltage between terminals TAM and E2 of ECM connector at each temperature. If OK , voltage at 25 °C (77 °F) : 1.35 - 1.75 V, at 40 °C (104 °F) : 0.85 - 1.25 V.
1. NG: Go to step 2 .
2. If OK , Proceed to next circuit inspection shown on problem symptoms table. See PROBLEM SYMPTOMS TABLE . However, if DTC 12 is displayed, check and replace A/C amplifier.
Check ambient temperature sensor.
PREPARATION: Disconnect ambient temperature sensor connector.

NOTE: As the temperature increases, the resistance decreases.

Check: resistance between terminals 1 and 2 of ambient temperature sensor connector at each temperature. If OK , Resistance at 25 °C (77 °F) : 1.6 - 1.8 kΩ, at 40 °C (104 °F) : 0.5 - 0.7 kΩ.

Fig 2: Testing Ambient Temperature Sensor
Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
1. NG: Replace ambient temperature sensor.
2. If OK , Check multiplex communication system. See HOW TO PROCEED WITH TROUBLESHOOTING MULTIPLEX COMMUNICATION SYSTEM .