Component Tests and General Diagnostics

ATP Switch Circuit Check

Description

The ATP indicator does not come on when the transfer is in neutral and the A/T lever is in neutral or, the ATP indicator stays on when the transfer case is not in neutral.

Diagnosis Procedure

Regarding Wiring Diagram information, refer to [Transfer Control Unit: Wiring Diagram] [1][2]Electrical Diagrams.

1. CHECK ATP SWITCH SIGNAL

With SDT

1 Start engine.
2 Select "Data list" mode for "4WD" with SDT.
3 Read out the value of "ATP SWITCH".






Without SDT

1 Start engine.
2 Check voltage between transfer control unit harness connector terminal and ground.











Are the inspection results normal?
YES
GO TO 5.
NO
GO TO 2.

2. CHECK HARNESS BETWEEN TRANSFER CONTROL UNIT AND ATP SWITCH

1 Turn ignition switch "OFF". (Stay for at least 5 seconds.)
2 Disconnect transfer control unit harness connector and the ATP switch harness connector.
3 Check continuity between transfer control unit harness connector M152 terminal 23 and ATP switch harness connector F55 terminal 8.











Also check harness for short to ground and short to power.

Does continuity exist?
YES
GO TO 3.
NO
Repair or replace damaged parts.

3. CHECK GROUND CIRCUIT

1 Turn ignition switch "OFF". (Stay for at least 5 seconds.)
2 Disconnect ATP switch harness connector.
3 Check continuity between ATP switch harness connector F55 terminal 9 and ground.











Also check harness for short to power.

Does continuity exist?
YES
GO TO 4.
NO
Repair open circuit or short to power in harness or connectors.

4. CHECK ATP SWITCH

1 Turn ignition switch "OFF". (Stay for at least 5 seconds.)
2 Remove ATP switch. Refer to [4WD System: Component Parts Location] Locations.
3 Push and release ATP switch and check continuity between ATP switch terminals 8 and 9.











Are the inspection results normal?
YES
GO TO 5.
NO
Replace ATP switch.

5. CHECK TRANSFER CONTROL UNIT

Check transfer control unit input/output signal. Refer to [Transfer Control Unit: Reference Value] Pinout Values and Diagnostic Parameters.

Are the inspection results normal?
YES
GO TO 6.
NO
Check transfer control unit pin terminals for damage or loose connection with harness connector. If any items are damaged, repair or replace damaged parts.

6. CHECK ATP WARNING LAMP

1 Turn ignition switch "ON". (Do not start engine.)
2 A/T selector lever "N" position and engage the parking brake.
3 Switch 4WD shift switch from 4H to 4LO or 4LO to 4H.

Does the ATP warning lamp turn ON while the actuator motor is operating?
YES
Inspection End.
NO
Refer to [ATP Warning Lamp Does Not Turn On] ATP Warning Lamp Does Not Turn On.

Component Inspection

1) Turn ignition switch "OFF". (Stay for at least 5 seconds.)
2) Disconnect ATP switch harness connector.
3) Remove ATP switch. Refer to [4WD System: Component Parts Location] Locations.
4) Push and release ATP switch and check continuity between ATP switch terminals 8 and 9.











5) If the inspection results are abnormal replace the ATP switch.