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Home >> Jeep >> 1996 >> Cherokee Classic, Part Time, Automatic >> Repair and Diagnosis (Single Page) >> Engine Performance >> System >> Engine Controls - Tests W/Codes - 4.0L >> Diagnostic Trouble Code (DTC) Identification >> Test TC-161A - EVAP Leak Monitor Large Leak Detected
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Test TC-161A - EVAP Leak Monitor Large Leak Detected

NOTE: For connector terminal identification, refer to CONNECTOR IDENTIFICATION . For wiring diagram, see WIRING DIAGRAMS article in this section.
CAUTION: Before proceeding with diagnosis, the following precautions must be followed: keep lighted cigarettes, sparks, flames or other ignition sources away from test area. Ensure test area is well ventilated. Ensure fuel tank is at least 1/2 full before performing test. Pressurizing fuel tank with less than 3 gallons of fuel may result in an explosion caused by ignition of fumes. Wear safety glasses when performing test procedures. If vehicle is not being tested on a hoist, ensure parking brake is applied and all wheels are blocked before starting test.
  1. DTC may be set by defective secondary seal on fuel filler neck, or a loose or missing fuel tank cap. Ensure fuel tank is at least 1/2 full. Using Evaporative (EVAP) System Testing Kit (6872A) and instructions printed on its cover, perform pressure pump self-test. Go to next step.
  2. Connect EVAP system testing kit pressure pump supply hose to Leak Detection Pump (LDP) test port. Set pressure hold to OPEN and set vent to CLOSED. Turn pump timer on and go to next step.
  3. Connect a vacuum pump to EVAP system testing kit vacuum tee and apply 18 in. Hg of vacuum to LDP. If LDP does not hold vacuum, repair LDP vacuum supply line for leak and repeat this step to verify repair. If LDP holds vacuum, go to next step.
  4. Turn ignition on. Using scan tool, actuate LDP solenoid while monitoring EVAP system testing kit vacuum gauge. If vacuum does not drop when solenoid is actuated, replace LDP and repeat this step to verify repair. If vacuum drops when solenoid is actuated, go to next step.
  5. Using vacuum pump, raise vacuum to 18 in. Hg vacuum. EVAP system Using testing kit, perform IM240 simulation (as described on cover of testing kit) while monitoring vacuum reading. If vacuum decreases more than 8 in. Hg in 2 minutes, go to step 8). If vacuum does not decrease more than 8 in. Hg in 2 minutes, go to next step.
  6. Condition required to set DTC is not present at this time. EVAP SYSTEM GROSS LEAK DTC sets if a leak larger than .080" exists in EVAP system. Possible causes are: defective LDP or a leak larger than .080" in EVAP system. Go to next step.
  7. Inspect all related hoses, wiring and connectors for signs of damage. Repair hoses, wiring and connectors as necessary and perform TEST VER-5A . If hoses, wiring and connectors are okay, refer to INACTIVE DTC CONDITION . Test is complete. Perform TEST VER-5A.
  8. Set pressure hold to OPEN and set vent to CLOSED. Turn pump timer on. Move EVAP system testing kit away from vehicle to prevent operating noise from interfering with test procedures. If pump noise still interferes with test procedures, turn pressure hold to CLOSED and turn pump timer off. Go to next step.
  9. Ensure EVAP system is under pressure. If EVAP system is not under pressure, leave pump timer on and turn pressure hold to OPEN. Using Ultrasonic Leak Detector (6904), check for leaks at fuel tank cap, fuel tank rollover valve, charcoal canister, LDP, and EVAP purge solenoid. Repair or replace leaking component as necessary and perform TEST VER-5A . If no leaks exist, replace LDP and filter, and perform TEST VER-5A.
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