A/T Does Not Shift: 5TH Gear->4TH Gear

A/T Does Not Shift: 5th gear -> 4th gear

SYMPTOM: When shifted from 5M to 4M position in manual mode, does not downshift from 5th to 4th gear.

DIAGNOSTIC PROCEDURE
1. CHECK A/T FLUID LEVEL
Check the A/T fluid level. Refer to "A/T FLUID CHECK".
OK or NG
OK >>GO TO 2.
NG >>Refill ATF.

2. CHECK SELF-DIAGNOSTIC RESULTS
Perform self-diagnosis.
Is any malfunction detected by self-diagnostic?
YES >>Check the malfunctioning system.
NO >>GO TO 3.

3. DETECT MALFUNCTIONING ITEM
1. Control valve assembly. Refer to "Control Valve Assembly".
2. Disassemble A/T. Refer to "DISASSEMBLY".
3. Check the following items:
^ Forward and direct clutch assembly. Refer to "DISASSEMBLY".
^ 2nd coast brake. Refer to "Oil Pump. 2nd Coast Brake & 2nd Brake". "One-Way Clutch Outer Race Sub Assembly & 2nd Coast Brake Hub & One-Way Clutch No.1".
^ One-way clutch No.1. Refer to "One-Way Clutch Outer Race Sub Assembly & 2nd Coast Brake Hub & One-Way Clutch No.1".
OK or NG
OK >>GO TO 4.
NG >>Repair or replace damaged parts.

4. CHECK TCM
1. Check TCM input/output signal. Refer to "TCM Input/Output Signal Reference Values". Pinout Values and Diagnostic Parameters
2. If NG, recheck TCM pin terminals for damage or loose connection with harness connector.
OK or NG
OK >>GO TO 5.
NG >>Repair or replace damaged parts.

5. CHECK SYMPTOM
Check again.
OK or NG
OK >> INSPECTION END
NG >>Repair or replace damaged parts.