Last Modified: 7-3-2017 6.8:8.0.40 Doc ID: RM0000018NH005X
Model Year Start: 2007 Model: LX470 Prod Date Range: [08/2006 -           ]
Title: AIR CONDITIONING: AIR CONDITIONING SYSTEM: Compressor Circuit; 2007 MY LX470 [08/2006 -        ]

Compressor Circuit

DESCRIPTION

The A/C amplifier outputs the magnetic clutch ON signal from terminal ACT to the ECM. When the ECM receives this signal, it sends a signal from terminal MGC and switches the A/C magnetic clutch relay ON, thus turning on the A/C magnetic clutch.

WIRING DIAGRAM

INSPECTION PROCEDURE

HINT:

When using the intelligent tester, start from *1. When not using the intelligent tester, start from *2.

PROCEDURE

1.

PERFORM ACTIVE TEST USING INTELLIGENT TESTER*1

(a) Connect the intelligent tester (with CAN VIM) to the DLC3.

(b) Turn the ignition switch ON and push the intelligent tester main switch ON.

(c) Select the item "A/C MAG CLUTCH" in the ACTIVE TEST and read its value displayed on the intelligent tester.

OK

Item

Measurement Item/Display (Range)

Diagnostic Note

A/C MAG CLUTCH

A/C Magnet Clutch Status/ON or OFF

-

HINT:

Check with the engine running.

NG

GO TO STEP 3

OK

2.

READ VALUE USING INTELLIGENT TESTER

(a) Connect the intelligent tester (with CAN VIM) to the DLC3.

(b) Turn the ignition switch ON and push the intelligent tester main switch ON.

(c) Select the item "A/C SIG" in the DATA LIST and read its value displayed on the intelligent tester.

Item

Measurement Item/Display (Range)

Normal Condition

Diagnostic Note

A/C SIG

A/C SW Status/ON or OFF
  • A/C SW Push: ON
  • A/C SW Release: OFF

-
NG

GO TO STEP 9

OK

END

3.

INSPECT MAGNETIC CLUTCH RELAY*2

(a) Disconnect the A4 magnetic clutch connector.

(b) Turn the ignition switch ON.

(c) Push the A/C switch ON.

(d) Measure the voltage of the wire harness side connectors.

Standard voltage:

Tester Connection

Specified Condition

A4 - 3 - Body ground

10 to 14 V
OK

GO TO STEP 9

NG

4.

INSPECT FUSE (A/C)

(a) Remove the A/C fuse from the cowl side junction block LH.

(b) Measure the resistance of the fuse.

OK:

Below 1 Ω

NG

REPLACE A/C FUSE

OK

5.

CHECK WIRE HARNESS (BATTERY - MAGNETIC CLUTCH RELAY)

(a) Disconnect the 1B engine room junction block connector.

(b) Turn the ignition switch ON.

(c) Measure the voltage of the wire harness side connectors.

Standard voltage:

Tester Connection

Specified Condition

1B - 16 - Body ground

10 to 14 V
NG

REPAIR OR REPLACE HARNESS AND CONNECTOR

OK

6.

CHECK WIRE HARNESS (AIR CONDITIONING AMPLIFIER - MAGNETIC CLUTCH RELAY)

(a) Disconnect the 1B engine room junction block connector.

(b) Disconnect the A47 and A49 A/C amplifier connector.

(c) Disconnect the A4 magnetic clutch connector.

(d) Measure the resistance of the wire harness side connectors,

Standard resistance:

Tester Connection

Specified Condition

A47-7 (MGC) - 1B-8

Below 1 Ω

A47-7 (MGC) - Body ground

10 k Ω or higher

1B-26 - A4-3

Below 1 Ω

1B-26 - Body ground

10 k Ω or higher

A49-12 (GND) - Body ground

Below 1 Ω
NG

REPAIR OR REPLACE HARNESS AND CONNECTOR

OK

7.

CHECK MAGNETIC CLUTCH RELAY

(a) Disconnect the 1B engine room junction block connector.

(b) Measure the resistance of the relay.

Standard resistance:

Tester Connection

Specified Condition

1B-16 - 1B-26

10 k Ω or higher

1B-16 - 1B-26

Below 1 Ω

(When battery voltage is applied to terminals 1B-16 and 1B-8.)
NG

REPLACE ENGINE ROOM JUNCTION BLOCK ASSEMBLY

OK

8.

CHECK MAGNETIC CLUTCH ASSEMBLY

(a) Disconnect the magnetic clutch connector.

(b) Connect the positive (+) lead connected to the battery to the magnetic clutch connector terminal 3 and check the magnetic clutch.

OK:

Magnetic clutch is energized.

NG

REPLACE MAGNETIC CLUTCH ASSEMBLY

OK

9.

CHECK WIRE HARNESS (AIR CONDITIONING AMPLIFIER - ECM)

(a) Disconnect the A47 and A49 A/C amplifier connectors.

(b) Disconnect the E9 ECM connector.

(c) Measure the resistance of the wire harness side connectors.

Standard resistance:

Tester Connection

Specified Condition

A47-11 (AC1) - E9-24 (AC1)

Below 1 Ω

A47-11 (AC1) - Body ground

10 k Ω or higher

A49-4 (ACT) - E9-25 (ACT)

Below 1 Ω

A49-4 (ACT) - Body ground

10 k Ω or higher
NG

REPAIR OR REPLACE HARNESS AND CONNECTOR

OK

10.

CHECK AIR CONDITIONING AMPLIFIER

(a) Remove the A/C amplifier with connectors still connected.

(b) Start the engine and push AUTO switch.

(c) Measure the voltage of the A/C amplifier connector and body ground when magnetic clutch is ON and OFF by A/C switch.

Standard voltage:

Switch Condition

Tester Connection

Specified Condition

ON

A49-4 (ACT) - Body ground

10 to 14 V

OFF

A49-4 (ACT) - Body ground

Below 1 V
NG

REPLACE AIR CONDITIONING AMPLIFIER

OK

REPLACE ECM