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

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 is detected for 3 seconds or more. This DTC is stored only in test mode.

DTC Code	Detection Condition	Trouble Area
C2194/94	The test mode procedure is performed.	ECM Harness or connector Tire pressure warning ECU

WIRING DIAGRAM
CAUTION / NOTICE / HINT

NOTICE:

• When replacing the tire pressure warning ECU, read the transmitter IDs stored in the old ECU using the Techstream and write them down before removal.
• It is necessary to perform registration of the transmitter IDs into the tire pressure warning ECU after the ECU and/or the tire pressure warning valve and transmitter has been replaced (See page ).

PROCEDURE

1. READ VALUE USING TECHSTREAM (ENGINE SPEED)

(a) Turn the ignition switch off.

(b) Connect the Techstream to the DLC3.

(c) Turn the ignition switch to ON.

(d) Turn the Techstream on.

(e) Enter the following menus: Chassis / Tire Pressure Monitor / Data List.

(f) 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	The speed indicated on the combination meter.

OK:

Engine speed indicated on the Techstream and on the combination meter are the same.

OK

USE SIMULATION METHOD TO CHECK

NG

1. INSPECT TIRE PRESSURE WARNING ECU (TACH SIGNAL)

(a) Disconnect the F7 ECU connector.

(b) Start the engine.

(c) Check the waveform of the ECU connector using an oscilloscope while idling the engine. OK: Tester Connection Condition Specified Condition F7-4 (TACH) - F7-9 (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. Text in Illustration *a Rear view of wire harness connector (to Tire Pressure Warning ECU)

OK

REPLACE TIRE PRESSURE WARNING ECU

NG

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

(a) Disconnect the F7 ECU connector.

(b) Disconnect the F50 ECM connector.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
F7-4 (TACH) - F50-29 (TACH)	Always	Below 1 Ω
F7-4 (TACH) - Body ground	Always	10 kΩ or higher

OK

REPLACE ECM

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR