ATP Warning Lamp Does Not Turn On
ATP Warning Lamp Does Not Turn On
Description+
ATP warning lamp does not turn ON when the transfer case is switched in or out of 4LO with the A/T selector lever in N position.
Diagnosis Procedure
Regarding Wiring Diagram information, refer to [Transfer Control Unit: Wiring Diagram] [1][2]Electrical Diagrams.
1. CHECK SYSTEM FOR CAN COMMUNICATION LINE
Perform "DTC check". Refer to [SDT Function (4WD)] Scan Tool Testing and Procedures.
Do the "DTC check" results indicate CAN communication?
YES
Perform trouble diagnosis for CAN communication line. Refer to [DTC Index: Transfer Control Unit] DTC Index Transfer Control Unit.
NO
GO TO 2.
2. CHECK SYSTEM FOR 4WD SHIFT SWITCH
Perform trouble diagnosis for 4WD shift switch system. Refer to [P1813 4WD Shift Switch] P1813.
Are the inspection results normal?
YES
GO TO 3.
NO
Repair or replace damaged parts.
3. CHECK SYSTEM FOR TRANSMISSION RANGE (A/T MODELS) OR PNP (M/T MODELS) SWITCH SIGNAL
Perform trouble diagnosis for transmission range (A/T models) or PNP (M/T models) switch signal system. Refer to [P1816 PNP Switch (A/T)] PNP Switch (A/T) (A/T models) or [P1816 PNP Switch (M/T)] PNP Switch (M/T) (M/T models).
Are the inspection results normal?
YES
GO TO 4.
NO
Repair or replace damaged parts.
4. CHECK SYSTEM FOR ATP SWITCH
Perform trouble diagnosis for ATP switch system. Refer to [ATP Switch Circuit Check] Component Tests and General Diagnostics.
Are the inspection results normal?
YES
GO TO 5.
NO
Repair or replace damaged parts.
5. CHECK ATP WARNING LAMP CIRCUIT
1 Disconnect ATP switch harness connector.
2 Turn ignition switch "ON". (Do not start engine.)
3 Ground terminal 8 on ATP switch connector F55 using suitable wiring.
4 Turn ignition switch "OFF". (Stay for at least 5 seconds.)
Does ATP warning lamp turn on?
YES
GO TO 9.
NO
GO TO 6.
6. CHECK HARNESS BETWEEN TRANSFER CONTROL UNIT AND COMBINATION METER
1 Turn ignition switch "OFF". (Stay for at least 5 seconds.)
2 Disconnect transfer control unit harness connector and combination meter harness connector.
3 Check continuity between transfer control unit harness connector M153 terminal 39 and combination meter harness connector M24 terminal 21.
Also check harness for short to ground and short to power.
Does continuity exist?
YES
GO TO 7.
NO
Repair or replace damaged parts.
7. CHECK HARNESS BETWEEN COMBINATION METER AND ATP SWITCH
1 Turn ignition switch "OFF". (Stay for at least 5 seconds.)
2 Disconnect ATP switch harness connector.
3 Check continuity between combination meter harness connector M24 terminal 1 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 8.
NO
Repair or replace damaged parts.
8. SYMPTOM CHECK
Check again.
Does the symptom still occur?
YES
GO TO 9.
NO
Inspection End.
9. 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 10.
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.
10. CHECK TRANSFER INNER PARTS
1 Disassemble transfer assembly. Refer to [Transfer Assembly: Disassembly and Assembly] Transfer Assembly.
2 Check transfer inner parts.
Are the inspection results normal?
YES
Inspection End.
NO
Repair or replace damaged parts.