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Engine Controls - System & Component Testing: Overview Jeep Wrangler II

Testing & Diagnostics ~327 words

CHECKING MAP SENSOR OPERATION

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. After each repair procedure has been completed, reconnect all components. Perform appropriate verification test to ensure system is functioning properly. Perform POWERTRAIN VERIFICATION TEST VER-2 under VERIFICATION TESTS to ensure system is functioning properly.

Turn ignition off. Install vacuum "T" fitting and vacuum gauge at vacuum source on intake manifold. Start engine and allow engine to idle. If engine will not idle, maintain a constant RPM greater than idle. Note engine vacuum on vacuum gauge. Using scan tool, read MAP sensor vacuum. If MAP sensor vacuum is within one in. Hg of engine vacuum on vacuum gauge, MAP sensor is operating properly. Test is complete. If MAP sensor vacuum is not within one in. Hg of engine vacuum on vacuum gauge, replace MAP sensor.

CHECKING THROTTLE POSITION SENSOR OPERATION

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-2 under VERIFICATION TESTS to ensure system is functioning properly.

  1. Turn ignition on. Ensure throttle is fully closed and against throttle stop. Using scan tool, read TP sensor voltage with throttle fully closed. If voltage is 1.5 volts or less, go to next step. If voltage is more than 1.5 volts, replace TP sensor.
  2. Using scan tool, monitor TP sensor voltage while slowly moving throttle from closed position to fully open position. If voltage changes smoothly from about 0.8 volt to more than 3.5 volts, TP sensor is functioning properly. Test is complete. If voltage does not change smoothly from about 0.8 volt to more than 3.5 volts, replace TP sensor.

CHECKING RADIATOR FAN OPERATION

Note. For circuit identification and wiring diagram, see WIRING DIAGRAMS article. After each repair procedure has been completed, reconnect all components. Perform POWERTRAIN VERIFICATION TEST VER-2 under VERIFICATION TESTS to ensure system is functioning properly.

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