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Test NTC-21A: Checking Oil Pressure Sensor

NOTE: This test does not apply to AN, BE/BR and DN bodies. For connector terminal identification, see CONNECTOR IDENTIFICATION . For component location and wiring diagram, see WIRING DIAGRAMS article.
  1. Check and correct oil level as necessary. Turn ignition off. While holding down TRIP ODOMETER button and observing oil pressure gauge, turn ignition switch to ON position on AB body or to RUN position on all other bodies. If oil pressure gauge does not reach calibration points 0, 1/2 and FULL, replace oil pressure gauge and perform TEST VER-2A: ROAD TEST VERIFICATION . If oil pressure gauge reaches calibration points, go to next step.
  2. On all bodies except AB body, go to next step. On AB body, if oil pressure gauge reads FULL at all times with ignition on, go to step 9)  . If oil pressure gauge does not read FULL at all times with ignition on, go to next step.
  3. Turn ignition off. Disconnect oil pressure sensor connector. Inspect connector and terminals for damage. Repair connector and terminals as necessary and perform TEST VER-2A: ROAD TEST VERIFICATION . If connector and terminals are okay, go to next step.
  4. Connect a jumper wire across oil pressure sensor connector. If oil pressure gauge goes to FULL on AB body, perform TEST NTC-21B: CHECKING OIL PRESSURE SENSOR . If oil pressure gauge goes to FULL on all other bodies, go to step 11)  . If oil pressure gauge does not go to FULL, go to next step.
  5. On AB body, go to step 8)  . On all other bodies, turn ignition off. Disconnect Powertrain Control Module (PCM) White connector. Inspect connector and terminals for damage. Repair connector and terminals as necessary and perform TEST VER-2A: ROAD TEST VERIFICATION . If connector and terminals are okay, go to next step.
  6. Using an external ohmmeter, check resistance of oil pressure sensor signal circuit (Gray/Yellow wire on TJ and XJ bodies; Gray/White wire on ZJ body) between oil pressure sensor connector and PCM. If resistance is 5 ohms or more, repair open signal circuit and perform TEST VER-2A: ROAD TEST VERIFICATION . If resistance is less than 5 ohms, go to next step.
  7. Check resistance of oil pressure sensor ground circuit (Brown/Yellow wire on TJ and XJ bodies; Black/Light Blue wire on ZJ body) between oil pressure sensor and PCM. If resistance is 5 ohms or more, repair open ground circuit and perform TEST VER-2A: ROAD TEST VERIFICATION . If resistance is less than 5 ohms, replace PCM and perform TEST VER-2A: ROAD TEST VERIFICATION .
  8. Using a 12-volt test light connected to battery voltage, probe oil pressure sensor connector, ground circuit (Black/Light Blue wire). If test light does not come on, repair open ground circuit and perform TEST VER-2A: ROAD TEST VERIFICATION . If test light comes on, repair open oil pressure sensor signal circuit (Black/Light Blue wire) and perform TEST VER-2A: ROAD TEST VERIFICATION .
  9. Disconnect oil pressure sensor connector. Inspect connector and terminals for damage. Repair connector and terminals as necessary and perform TEST VER-2A: ROAD TEST VERIFICATION . If connector and terminals are okay, go to next step.
  10. If oil pressure gauge does not read FULL at all times with ignition on, replace oil pressure sensor and perform TEST VER-2A: ROAD TEST VERIFICATION . If oil pressure gauge reads FULL at all times with ignition on, repair short to ground in oil pressure sensor signal circuit (Gray wire) and perform TEST VER-2A: ROAD TEST VERIFICATION .
  11. Remove oil pressure sensor. Install oil pressure gauge in oil pressure sensor opening. Start engine and let it idle. Record oil pressure. See MINIMUM OIL PRESSURE SPECIFICATIONS  table. If oil pressure is not to specification, repair mechanical engine oil pressure problem as necessary and perform TEST VER-2A: ROAD TEST VERIFICATION . If oil pressure is to specification, replace oil pressure sensor and perform TEST VER-2A: ROAD TEST VERIFICATION .
MINIMUM OIL PRESSURE SPECIFICATIONS(1)

Engine Size psi (kg/cm2 )
2.5L & 4.0L 13 (.9)
5.2L & 5.9L 6 (.4)
(1) Specification is with engine at idle.
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