Engine Coolant Temperature Receiver Gauge Malfunction: Procedure

1. Check the input signal waveform.
   Fig 1: Identifying C11 Temp Communication Input Connector Terminals

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   1. Remove the combination meter assembly with connectors still connected.
   2. Connect the oscilloscope to the terminal C11-5 (TEMP COMMUNICATION INPUT) and body ground.
   3. Start the engine.
   4. Check the signal waveform according to the condition(s) in the table below.
      Fig 2: Identifying Signal Waveform Graph

      Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

      Item	Condition
      Tool setting	5 V/DIV., 100 ms/DIV.
      Vehicle condition	Engine idle speed

      HINT: 

      As the coolant temperature rises, the period "A" shown in the illustration becomes longer.

      Reference

      Engine Coolant Temperature	A
      Less than 50°C (122.0°F)	96.304 to 100.304 ms
      83°C (181.4°F)	231.472 to 235.472 ms
      120°C (248.0°F)	383.024 to 387.024 ms

NG → See step   2 

OK → REPLACE COMBINATION METER ASSEMBLY 

1. Disconnect the C11 and E8 connectors.
   Fig 3: Identifying C11 & E8 Connector Terminals

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
2. Measure the resistance according to the value(s) in the table below.

   Standard resistance

   Tester Connection	Condition	Specified Condition
   TEMP COMMUNICATION INPUT (C11-5) - THWO (E8-14)	Always	Below 1 Ω
   TEMP COMMUNICATION INPUT (C11-5) - Body ground	Always	10 kΩ or higher

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK → REPLACE ECM