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 signal check mode (test mode), and cleared when an engine speed signal of 1000 rpm is detected for 3 seconds or more. This DTC is output only in signal check mode.

DTC No.	DTC Detection Condition	Trouble Area
C2194/94	Test mode procedure is performed	ECM Wire 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 (See page ) of the transmitter IDs into the tire
  pressure warning ECU if the ECU has been replaced.

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	Speed indicated on 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 D31 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
D31-4 (TACH) - D31-9 (GND)	Idling	Correct waveform appears as shown

Text in Illustration

*1	Rear view of wire harness connector (to Tire Pressure Warning ECU)

Tool Setting

Item	Contents
Tool Setting	5 V/DIV., 10 ms/DIV.

HINT:

The wavelength becomes shorter as the engine speed increases.

OK

REPLACE TIRE PRESSURE WARNING ECU

NG

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

(a) Disconnect the D31 ECU connector.

(b) Disconnect the A41 or A49 ECM connector.

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

Standard Resistance:

Tester Connection	Condition	Specified Condition
D31-4 (TACH) - A41-15 (TACH)	Always	Below 1 Ω
D31-4 (TACH) - A49-26 (TACH)	Always	Below 1 Ω
D31-4 (TACH) - Body ground	Always	10 kΩ or higher

Text in Illustration

*1	Front view of wire harness connector (to Tire Pressure Warning ECU)
*2	Front view of wire harness connector (to ECM)
*3	2GR-FE
*4	1AR-FE

Result	Proceed to
OK (for 2GR-FE)	A
OK (for 1AR-FE)	B
NG	C

A

REPLACE ECM (for 2GR-FE)

B

REPLACE ECM (for 1AR-FE)

C

REPAIR OR REPLACE HARNESS OR CONNECTOR