Symptom:

WARNING: This page is about a different car, the 2002 Nissan Sentra. However, it is still accessible from the selected car via links, so may be relevant.

A/T does not hold lock-up condition for more than 30 seconds .

CHECK DIAGNOSTIC RESULTS
Does self-diagnosis show damage to engine speed signal circuit after cruise test?

Fig 1: Checking Self-Diagnostic Result
Courtesy of NISSAN MOTOR CO., U.S.A.

Yes or No
1. Yes: Check engine speed signal circuit. Refer to DTC P0725 ENGINE SPEED SIGNAL .
2. No: GO TO 2.
CHECK A/T FLUID CONDITION
1. Remove oil pan.
2. Check A/T fluid condition.
  
  Fig 2: Checking Automatic Transaxle Fluid Condition
  Courtesy of NISSAN MOTOR CO., U.S.A.
OK or NG
1. OK: GO TO 3.
2. NG: GO TO 5.
DETECT MALFUNCTIONING ITEM
1. Remove control valve assembly. Refer to REMOVAL .
2. Check the following items:
  - Torque converter clutch control valve
  - Pilot valve
  - Pilot filter
OK or NG
1. OK: GO TO 4.
2. NG: Repair or replace damaged parts.
CHECK SYMPTOM
Check again.

OK or NG
1. OK: INSPECTION END
2. NG:
  1. Perform TCM input/output signal inspection.
  2. If NG, recheck TCM pin terminals for damage or loose connection with harness connector.
DETECT MALFUNCTIONING ITEM
1. Remove control valve assembly. Refer to REMOVAL .
2. Check the following items:
  - Torque converter clutch control valve
  - Pilot valve
  - Pilot filter
3. Disassemble A/T.
4. Check torque converter and oil pump assembly.
OK or NG
1. OK: GO TO 4.
2. NG: Repair or replace damaged parts.