Dtc C2194/94 Engine Speed Signal Error (Test Mode Dtc)

Suspension. Yaris. Ncp93, 131
Tire Pressure Monitoring. Yaris. Ncp93, 131

DESCRIPTION

WIRING DIAGRAM

INSPECTION PROCEDURE

READ VALUE USING TECHSTREAM (ENGINE SPEED)

INSPECT TIRE PRESSURE WARNING ECU (TACH SIGNAL)

CHECK HARNESS AND CONNECTOR (TIRE PRESSURE WARNING ECU - ECM)

DTC C2194/94 Engine Speed Signal Error (Test Mode DTC)


DESCRIPTION

The tire pressure warning ECU receives an engine speed signal from the ECM. This DTC is stored upon entering test mode, and cleared when an engine speed signal of 1000 rpm or more is detected for 3 seconds or more. This DTC is output only in test mode.

DTC No.
DTC Detection Condition
Trouble Area
C2194/94
Engine speed signal circuit malfunction
  1. ECM
  2. Harness or connector
  3. Tire pressure warning ECU

WIRING DIAGRAM


Yaris. Ncp93, 131.Tire Pressure Monitoring.Tire Pressure Warning System (For Sedan). Dtc C2194/94 Engine Speed Signal Error (Test Mode Dtc)


INSPECTION PROCEDURE

NOTICE:
  1. When replacing the tire pressure warning ECU, read the transmitter IDs stored in the old ECU using a Techstream and write them down before removal.
  2. It is necessary to perform registration (YARIS_NCP93 RM000000XN107JX.html) of the transmitter IDs into the tire pressure warning ECU after the ECU has been replaced.
1.READ VALUE USING TECHSTREAM (ENGINE SPEED)

  1. Turn the ignition switch off.

  1. Connect a Techstream to the DLC3.

  1. Turn the ignition switch ON and the Techstream ON.

  1. Enter the following menus: Chassis / Tire Pressure Monitor / Data List

  1. Check that the values indicated on the Techstream and on the combination meter are the same.

    Tire Pressure Monitor
    Tester Display
    		Measurement Item/Range
    		Normal Condition
    		Diagnostic Note
    Engine Speed
    		Engine speed/
    min.: 0 rpm
    max.: 65535 rpm
    		Almost same as actual engine speed
    		Speed indicated on combination meter
    OK:
    Engine speed indicated on the Techstream and on the combination meter are the same.


NG
Go to step 2
OK

USE SIMULATION METHOD TO CHECK (YARIS_NCP93 RM00000135202EX.html)

2.INSPECT TIRE PRESSURE WARNING ECU (TACH SIGNAL)


    Yaris. Ncp93, 131.Tire Pressure Monitoring.Tire Pressure Warning System (For Sedan). Dtc C2194/94 Engine Speed Signal Error (Test Mode Dtc)

  1. Disconnect the D78 ECU connector.

  1. Start the engine.

  1. Check the waveform of the ECU connector using an oscilloscope, while idling the engine.

    OK:
    Tester Connection
    		Condition
    		Specified Condition
    D78-4 (TACH) - D78-9 (GND)
    		Idling
    		Correct waveform is as shown
    Tool Setting
    Item
    		Contents
    Tool Setting
    		5 V/DIV., 10 ms/DIV.
    HINT:
    The wavelength becomes shorter as the engine speed increases.


NG
Go to step 3
OK

REPLACE TIRE PRESSURE WARNING ECU (YARIS_NCP93 RM0000024T801VX.html)

3.CHECK HARNESS AND CONNECTOR (TIRE PRESSURE WARNING ECU - ECM)


    Yaris. Ncp93, 131.Tire Pressure Monitoring.Tire Pressure Warning System (For Sedan). Dtc C2194/94 Engine Speed Signal Error (Test Mode Dtc)

  1. Disconnect the D78 ECU connector.

  1. Disconnect the A21 ECM connector.

  1. Measure the resistance according to the value(s) in the table below.

    Standard resistance:
    Tester Connection
    		Condition
    		Specified Condition
    D78-4 (TACH) - A21-15 (TACH)
    		Always
    		Below 1 Ω
    D78-4 (TACH) - Body ground
    		Always
    		10 kΩ or higher


NG
REPAIR OR REPLACE HARNESS OR CONNECTOR
OK

REPLACE ECM (YARIS_NCP93 RM000001CN002AX.html)