Malfunction in Tachometer: Wiring Diagram

1. Operate the intelligent tester according to the display and select the "Active Test".

   Combination meter 

   COMBINATION METER SPECIFICATION
   
   

   Item	Test Details	Diagnostic Note
   TACHOMETER	0 RPM / 1,000 RPM / 2,000 RPM / 3,000 RPM / 4,000 RPM / 5,000 RPM / 6,000 RPM / 7,000 RPM	-

   OK : Needle indication is normal. 

NG : REPLACE COMBINATION METER 

OK : GO TO NEXT STEP 

1. Operate the intelligent tester according to the display and select the "Data List".

   Combination meter 

   COMBINATION METER SPECIFICATION
   
   

   Item	Measurement Item/Range (Display)	Normal Condition	Diagnostic Note
   TACHO METER	Engine speed/ Min.: 0 RPM, Max.: 12,750 RPM	Almost same as actual engine speed (When engine is running)	-

   OK : Engine speed displayed on the tester is almost the same as the actual engine speed. 

NG : Go to step 3 

OK : REPLACE COMBINATION METER 

1. Operate the intelligent tester according to the steps on the display and select the "Data List".

   ECM 

   ITEM CONDITION CHART
   
   

   Item	Measurement Item/Range (Display)	Normal Condition	Diagnostic Note
   ENGINE	SPD Engine speed/ Min.: 0 RPM, Max.: 16,383 RPM	Almost same as actual engine speed (When engine is running)	-

NG : GO TO ENGINE CONTROL SYSTEM 

OK : GO TO NEXT STEP 

1. Check the input signal waveform.
   1. Remove the combination meter with connector still connected.
   2. Connect the oscilloscope to terminal K31-27 and body ground.
   3. Start the engine.
      Fig 2: Identifying K31 Connector Terminal 27

      Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   4. Check the signal waveform of the connector.
      ITEM CONDITION CHART
      
      

      Item	Condition
      Tool setting	5 V/DIV., 10 ms/DIV.
      Vehicle condition	Engine idle speed

      OK : As shown in the illustration 

OK : REPLACE COMBINATION METER 

Fig 3: Identifying Waveform

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

NG : GO TO NEXT STEP 

1. Disconnect the A7 ECM connector.
2. Disconnect the K31 meter connector.
3. Measure the resistance of the wire harness side connectors.

   Standard resistance 

   TESTER CONNECTION CONDITION CHART
   
   

   Tester Connection	Condition	Specified Condition
   K31-27 - A7-16	Always	Below 1 Ω
   K31-27 - Body ground	Always	10 kΩ or higher

NG : REPAIR OR REPLACE HARNESS AND CONNECTOR 

Fig 4: Identifying A7 ECM Connector And K31 Meter Connector

Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002

OK : REPLACE ECM