Tachometer Malfunction: Procedure

1. Connect the Techstream to the DLC3.
2. Turn the ignition switch to the ON position.
3. Turn the Techstream on.
4. Enter the following menus: Body Electrical / Combination Meter / Active Test.
5. Check the operation by referring to the values in the table below.
   COMBINATION METER:
   
   

   Tester Display	Test Part	Control Range	Diagnostic Note
   Tachometer Operation	Tachometer	0, 1000, 2000, 3000, 4000, 5000, 6000, 7000 (rpm)	Confirm that the vehicle is stopped, engine idling

   OK

   Needle indication is normal.

NG → REPLACE COMBINATION METER ASSEMBLY 

OK: Go to next step 

1. Connect the Techstream to the DLC3.
2. Turn the ignition switch to the ON position.
3. Turn the Techstream on.
4. Enter the following menus: Body Electrical / Combination Meter / Data List.
5. Check the values by referring to the values in the table below.
   COMBINATION METER:
   
   

   Tester Display	Measurement Item/Range	Normal Condition	Diagnostic Note
   Engine Rpm	Engine speed/Min.: 0 rpm, Max.: 12750 rpm	Almost same as actual engine speed (When engine is running)	If data received from the ECM exceeds the range that can be displayed on the meter, the meter continues to display the maximum value of the range.

   Result

   Result	Proceed to
   The tachometer indication differs from the engine speed displayed on the Techstream.	A
   Engine speed displayed on the Techstream is almost the same as the tachometer indication.	B
   Both the tachometer indication and the engine speed displayed on the Techstream are 0.	C

C → See step   4 

B → See step   3 

A → REPLACE COMBINATION METER ASSEMBLY 

1. Connect the Techstream to the DLC3.
2. Turn the ignition switch to the ON position.
3. Turn the Techstream on.
4. Enter the following menus: Powertrain / Engine and ECT /Data List.
5. Check the values by referring to the table below.
   ENGINE AND ECT:
   
   

   Tester Display	Measurement Item/Range	Normal Condition	Diagnostic Note
   Engine Speed	Engine speed/Min.: 0 rpm, Max.: 16383.75 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 The Appropriate SFI SERVICE INFORMATION 

OK: Go to next step 

1. Disconnect the C8 and E6 connectors.
   Fig 1: Identifying C8 & E6 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
   C8-7 (TACH) - E6-1 (TACH)	Always	Below 1 Ω
   C8-7 (TACH) - Body ground	Always	10 kΩ or higher

NG → REPAIR OR REPLACE HARNESS OR CONNECTOR 

OK: Go to next step 

1. Check the input signal waveform.
   Fig 2: Identifying Input Signal Waveform

   Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002
   1. Remove the combination meter with the connector still connected.
   2. Connect the oscilloscope to terminal C8-7 (TACH) and body ground.
   3. Start the engine.
   4. Check the signal waveform according to the condition(s) in the table below.

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

      OK

      The waveform is displayed as shown in the illustration.

NG → REPLACE ECM 

OK → REPLACE COMBINATION METER ASSEMBLY