Toyota Tundra Service Manual: Air Conditioning Compressor Magnetic Clutch Circuit

DESCRIPTION

When the air conditioning amplifier is turned on, a magnetic clutch ON signal is sent from the MGC terminal of the air conditioning amplifier. Then, the magnetic clutch relay (MG CLT) turns on to operate the magnetic clutch.

WIRING DIAGRAM

PROCEDURE

1.

READ VALUE USING TECHSTREAM (A/C SIGNAL)

(a) Use the Data List to check if the air conditioning signal is functioning properly.

Engine and ECT

Tester Display

Measurement Item / Range

Normal Condition

Diagnostic Note

A/C Signal

Air conditioning switch signal /

ON or OFF

ON: Air conditioning ON

OFF: Air conditioning OFF

-

OK:

The display is as specified in the normal condition.

OK

PROCEED TO NEXT CIRCUIT INSPECTION SHOWN IN PROBLEM SYMPTOMS TABLE

NG

2.

INSPECT FUSE (ECU-IG1 NO.3)

(a) Remove the ECU-IG1 NO.3 fuse from the driver side junction block.

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

Standard resistance:

Tester Connection

Condition

Specified Condition

ECU-IG1 NO.3 fuse

Always

Below 1 Ω

NG

REPLACE FUSE

OK

3.

CHECK HARNESS AND CONNECTOR (ENGINE ROOM RELAY BLOCK, JUNCTION BLOCK - BATTERY)

(a) Remove the magnetic clutch relay (MG CLT) from the engine room relay block, junction block.

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

Standard voltage:

Tester Connection

Switch Condition

Specified Condition

Engine room relay block magnetic clutch relay terminal 5 - Body ground

Ignition switch ON

11 to 14 V

Ignition switch off

Below 1 V

Engine room relay block magnetic clutch relay terminal 1 - Body ground

Ignition switch ON

11 to 14 V

Ignition switch off

Below 1 V

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

4.

INSPECT MAGNETIC CLUTCH RELAY (MG CLT)

(a) Remove the magnetic clutch relay from the engine room relay block, junction block.

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

Standard resistance:

Tester Connection

Condition

Specified Condition

3 - 5

When battery voltage is not applied between terminals 1 and 2

10 kΩ or higher

When battery voltage is applied to terminals 1 and 2

Below 1 Ω

NG

REPLACE MAGNETIC CLUTCH RELAY

OK

5.

CHECK HARNESS AND CONNECTOR (AIR CONDITIONING AMPLIFIER - BATTERY)

(a) Disconnect the J19 air conditioning amplifier connector.

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

Standard voltage:

Tester Connection

Switch Condition

Specified Condition

J19-20 (MGC) - Body ground

Ignition switch OFF

Below 1 V

Ignition switch ON

11 to 14 V

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

OK

6.

CHECK AIR CONDITIONING AMPLIFIER (MGC VOLTAGE)

(a) Reconnect the J19 air conditioning amplifier connector.

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

Standard voltage:

Tester Connection

Switch Condition

Specified Condition

J19-20 (MGC) - Body ground

Engine is running

Blower switch LO

A/C switch ON

Below 1 V

Engine is running

Blower switch LO

A/C switch OFF

11 to 14 V

NG

REPLACE AIR CONDITIONING AMPLIFIER

OK

7.

INSPECT AIR CONDITIONING COMPRESSOR (COMPRESSOR HARNESS)

(a) Disconnect the D60 air conditioning compressor connector.

(b) Disconnect the magnetic clutch connector.

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

Standard resistance:

Tester Connection

Condition

Specified Condition

3 (MG+) - 1

Always

Below 1 Ω

3 (MG+) or 1 - Body ground

Always

10 kΩ or higher

NG

REPAIR AIR CONDITIONING COMPRESSOR

OK

8.

INSPECT MAGNETIC CLUTCH

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

Standard resistance:

Tester Connection

Condition

Specified Condition

1 - Body ground

Always

3.4 to 3.8 Ω

(b) When connector terminal 1 is connected to the positive (+) battery terminal, check that the following occurs: 1) the magnetic clutch's operating sound can be heard, and 2) the magnetic clutch's hub and rotor lock.

NG

REPLACE MAGNETIC CLUTCH

OK

9.

CHECK HARNESS AND CONNECTOR (AIR CONDITIONING COMPRESSOR - ENGINE ROOM RELAY BLOCK, JUNCTION BLOCK)

(a) Disconnect the D60 air conditioning compressor connector.

(b) Remove the magnetic clutch relay (MG CLT) from the engine room relay block, junction block.

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

Standard resistance:

Tester Connection

Condition

Specified Condition

D60-3 (MG+) - Engine room relay block magnetic clutch relay terminal 3

Always

Below 1 Ω

D60-3 (MG+) or Engine room relay block magnetic clutch relay terminal 3 - Body ground

Always

10 kΩ or higher

OK

REPLACE AIR CONDITIONING AMPLIFIER

NG

REPAIR OR REPLACE HARNESS OR CONNECTOR

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