Toyota Tundra Service Manual: Terminals Of Ecu

TERMINALS OF ECU

1. CHECK AIR CONDITIONING AMPLIFIER

(a) Measure the voltage and resistance according to the value(s) in the table below.

HINT:

Check from the rear of the connector with it connected to the air conditioning amplifier.

Terminal No. (Symbols)

Wiring Color

Terminal Description

Condition

Specified Condition

J19-1 (IG+) - J19-14 (GND)

P - W-B

Ignition power supply

Ignition switch ON

11 to 14 V

Ignition switch OFF

Below 1 V

J19-21 (B) - J19-14 (GND)

BR - W-B

Battery power source

Always

11 to 14 V

J19-14 (GND) - Body ground

W-B - Body ground

Ground

Always

Below 1 Ω

J19-5 (TAM) - J19-14 (GND)

V - W-B

Ambient temperature sensor signal

Ignition switch ON at 25°C (77°F)

1.35 to 1.75 V

Ignition switch ON at 40°C (104°F)

0.9 to 1.2 V

J19-8 (LOCK) - J19-14 (GND)

SB - W-B

Compressor lock sensor signal

Engine is running

Blower switch LO

A/C switch ON

Pulse generation

(see waveform 1)

J19-23 (BLW) - J19-14 (GND)

LG - W-B

Blower motor control signal

Ignition switch ON

Blower switch LO

Pulse generation

(see waveform 2)

J19-20 (MGC) - J19-14 (GND)

P - W-B

Compressor magnetic clutch operation signal

Engine is running

Blower switch LO

A/C switch OFF

11 to 14 V

Engine is running

Blower switch LO

A/C switch ON

Below 1 V

J19-13 (SG-2) - Body ground

G - Body ground

Ground for ambient temperature sensor

Always

Below 1 Ω

J19-37 (LIN1) - J19-14 (GND)

SB - W-B

LIN communication signal

Ignition switch ON

Pulse generation

J19-11 (CANH) - J19-14 (GND)

B - W-B

Hi-level CAN bus line

Ignition switch ON

Pulse generation

(see waveform 3)

J19-12 (CANL) - J19-14 (GND)

W - W-B

Lo-level CAN bus line

Ignition switch ON

Pulse generation

(see waveform 4)

z1-2 (BUS G) - Body ground

-

Ground for BUS IC

Always

Below 2 V

z1-3 (BUS) - z1-2 (BUS G)

-

BUS IC control signal

Ignition switch OFF → ON

Pulse generation

z1-4 (B BUS) - z1-2 (BUS G)

-

Power supply for BUS IC

Always

11 to 14 V

z1-5 (SGA) - Body ground

-

Ground for No. 1 cooler thermistor

Always

Below 2 V

z1-6 (TEA) - z1-5 (SGA)

-

No. 1 cooler thermistor signal

Ignition switch ON

No. 1 cooler thermistor at 0°C (32°F)

1.7 to 2.1 V

Ignition switch ON

No. 1 cooler thermistor at 15°C (59°F)

0.7 to 1.3 V

(b) Using an oscilloscope, check waveform 1.

Compressor lock signal

Terminal No. (Symbols)

Tool Setting

Condition

J19-8 (LOCK) - J19-14 (GND)

200 mV/DIV., 10 ms./DIV.

Engine is running

Blower switch LO

A/C switch ON

(c) Using an oscilloscope, check waveform 2.

Blower motor control signal

Terminal No. (Symbols)

Tool Setting

Condition

J19-23 (BLW) - J19-14 (GND)

1 V/DIV., 500 μsec./DIV.

Ignition switch ON

Blower switch LO

HINT:

When the blower level is increased, the duty ratio changes accordingly.

(d) Using an oscilloscope, check waveform 3.

CAN communication signal

Terminal No. (Symbols)

Tool Setting

Condition

J19-11 (CANH) - J19-14 (GND)

1 V/DIV., 10 μsec./DIV.

Ignition switch ON

HINT:

The waveform varies depending on the CAN communication signal.

(e) Using an oscilloscope, check waveform 4.

CAN communication signal

Terminal No. (Symbols)

Tool Setting

Condition

J19-12 (CANL) - J19-14 (GND)

1 V/DIV., 10 μsec./DIV.

Ignition switch ON

HINT:

The waveform varies depending on the CAN communication signal.

2. CHECK AIR CONDITIONING CONTROL ASSEMBLY

(a) Disconnect the J127 air conditioning control assembly connector.

(b) Measure the voltage and resistance according to the value(s) in the table below.

Terminal No. (Symbols)

Wiring Color

Terminal Description

Condition

Specified Condition

J127-4 (IG+) - J127-5 (GND)

SB - W-B

Ignition power supply

Ignition switch ON

11 to 14 V

Ignition switch OFF

Below 1 V

J127-5 (GND) - Body ground

W-B - Body ground

Ground

Always

Below 1 Ω

J127-7 (STX) - J127-5 (GND)

SB - W-B

LIN communication signal

Ignition switch ON

Pulse generation

    System Diagram

    Air Conditioning Unit

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