Test TC-160A - EVAP System Small Leak

NOTE: This diagnostic trouble code may be set by a loose fuel tank cap.

CAUTION: When performing test procedures, keep lighted cigarettes, sparks, flames or other ignition sources away from test area. Ensure test area is well ventilated. Ensure fuel tank contains 3-17 gallons of fuel before performing test. Pressurizing fuel tank with less than 3 gallons of fuel may result in an explosion caused by ignition of the 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 performing test procedures.

NOTE: For wiring diagram, see WIRING DIAGRAMS - 2.4L article.

Diagnostic trouble code may be set by a loose fuel tank cap. Ensure fuel tank contains at least 3 gallons of fuel.
Install vacuum pump on service "T" fitting in engine vacuum hose to leak detection pump. Leak detection pump is located below driver's side of steering gear, above engine cradle. See Fig 1.

Fig 1: Locating Leak Detection Pump
Using vacuum pump, apply 18 in. Hg of vacuum on engine vacuum hose to leak detection pump. Note if vacuum pump holds vacuum.
If vacuum can be maintained, go to next step. If vacuum cannot be maintained, check engine vacuum hose to leak detection pump for leaks. If engine vacuum hose to leak detection pump is okay, replace leak detection pump. Repeat this entire test to verify system operation.
Turn ignition on. Using scan tool, actuate leak detection pump solenoid while monitoring vacuum reading on vacuum pump. If vacuum decreases and then holds steady when leak detection pump solenoid is actuated, go to next step. If vacuum does not decrease and then hold steady when leak detection pump solenoid is actuated, replace leak detection pump. Repeat this entire test to verify system operation.
Evaporative System Testing Kit (6872A) is used to perform evaporative system pressure test. Perform pressure pump self-test by using instructions on cover of evaporative system testing kit.
Connect evaporative system pressure pump supply hose to EVAP system test port located near EVAP purge solenoid and passenger's side strut tower. See Fig 2.

Fig 2: Locating EVAP Purge Solenoid & Typical EVAP System Test Port
Set pressure hold to OPEN position and set vent to CLOSED position. Turn pump timer on. Perform IM240 simulation as described on cover of evaporative system testing kit while monitoring the pressure.
If pressure decreases more than 8 inches in 2 minutes, go to step 17). If pressure does not decrease more than 8 inches in 2 minutes, go to next step.
Conditions required to set DTC are not present at this time. Leak detection assembly detects a leak in EVAP system and seals EVAP system so leak detection test may be performed. Leak detection assembly consists of leak detection pump solenoid, leak detection pump incorporating a switch which monitors the pump movement, 2 check valves, spring diaphragm and a EVAP canister vent valve.
Immediately after a cold start with ambient temperature of 40-90°F (4.4-32°C) and engine coolant temperature is within 10°F (-12°C) of ambient temperature, leak detection pump solenoid is energized. When solenoid is energized, engine vacuum enters leak detection pump and draws the spring diaphragm upward, allowing atmospheric pressure to enter cavity on leak detection pump.
When leak detection pump solenoid is de-energized, this vents engine vacuum, allowing spring diaphragm to move downward, forcing the air out of cavity on leak detection pump and into the vent system. When leak detection pump solenoid is energized and de-energized, the cycle is repeated, resulting in a pumping effect.
After passing leak detection phase of the test, system pressure is maintained until purge system is activated, in effect creating a leak. If cycle rate increases due to the flow of the purge system, the test is passed and diagnostic test is complete. If cycle rate does not increase, an obstruction exists in the system.
Possible causes for DTC to be set are: defective leak detection pump or a leak larger than .040" and smaller than .080" in the evaporative system. Go to next step.
Inspect hoses for EVAP system at engine, EVAP purge solenoid, EVAP canister and leak detection pump. The EVAP purge solenoid is located near passenger's side strut tower. See Fig 2. EVAP canister is located on frame rail, directly below driver's seat. Inspect wiring and connectors at EVAP purge solenoid, leak detection pump and Powertrain Control Module (PCM). The PCM is located between driver's side front fender and power distribution center, near battery.
If hoses, wiring or connectors are damaged, repair as necessary. Perform TEST VER-5A. If no defective hoses, wiring or connectors exist, see INACTIVE TROUBLE CODE CONDITION. Perform TEST VER-5A.
Set pressure hold to OPEN position and set vent to CLOSED position. Turn pump timer on. Move evaporative system testing kit away from vehicle to prevent operating noise from interfering with test procedures.
Using Ultrasonic Leak Detector (300), check for leaks at fuel tank cap, fuel tank pressure release/rollover valve, EVAP purge solenoid, EVAP canister and leak detection pump. Fuel tank pressure release/rollover valve is located on fuel tank filler tube, just below fuel tank cap. The EVAP purge solenoid is located near passenger's side strut tower. See Fig 2. EVAP canister is located on frame rail, directly below driver's seat.
If leak exists at any component, repair or replace component as necessary. Perform TEST VER-5A. If no leaks exist, replace leak detection pump. Perform TEST VER-5A.