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Test TC-183A - Leak Detection Pump Solenoid Circuit

NOTE: For connector terminal ID, see the CONNECTOR IDENTIFICATION DIRECTORY. For wiring diagram, see WIRING DIAGRAMS - 3.3L article.
  1. Turn ignition on. Using scan tool, actuate leak detection pump solenoid and listen for clicking sound at leak detection pump. Leak detection pump is located below driver's side of steering gear, above engine cradle. See Figure. If clicking sound is heard at leak detection pump, go to next step. If clicking sound is not heard at leak detection pump, go to step 11).
    Fig 1: Locating Leak Detection Pump
    G95C35065
  2. Using scan tool, stop actuation of leak detection pump. 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 can be performed. Leak detection assembly consists of leak detection pump solenoid, leak detection pump incorporating leak detection pump pressure switch which monitors the pump movement, 2 check valves, spring diaphragm and a EVAP canister vent valve.
  3. 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.
  4. 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.
  5. After passing leak detection phase of the test, system pressure is maintained until the 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.
  6. The DTC may be stored in PCM if the state of leak detection pump solenoid does change. Possible causes are: open or shorted wiring for leak detection pump solenoid control circuit, defective leak detection pump solenoid, open fused ignition switch output. Go to next step.
    NOTE: Fused ignition switch output circuit (White/Black wire) from leak detection pump solenoid goes to power distribution center, and then to Positive Temperature Coefficient (PTC) No. 1 in junction block, located behind driver's side of instrument panel, to the left of steering column. The PTC receives voltage when ignition is on. The PTC is a specified amperage solid-state circuit breaker located in junction box. The PTC may reset when all current is removed from PTC for approximately 20 seconds.
  7. Inspect wiring and connectors between leak detection pump and Powertrain Control Module (PCM). The PCM is located between driver's side front fender and power distribution center, near battery.
  8. If wiring or connectors are defective, repair as necessary. Perform TEST VER-5A. If no defective wiring or connectors exist, go to next step.
  9. Using scan tool, actuate leak detection pump solenoid. While monitoring Leak Detection Pump (LDP) pressure switch state, wiggle wiring from leak detection pump to PCM.
  10. If scan tool indicates LDP pressure switch changes from UP to DOWN while wiggling wiring, repair wiring as necessary. Perform TEST VER-5A. If scan tool does not indicate LDP pressure switch changes from UP to DOWN while wiggling wiring, see INACTIVE TROUBLE CODE CONDITION. Perform TEST VER-5A.
  11. Turn ignition off. Disconnect connector at leak detection pump. Turn ignition on. Using voltmeter, check voltage at terminal No. 3 (White/Black wire) on connector for leak detection pump.
  12. If voltage is more than 10 volts, go to next step. If voltage is 10 volts or less, repair open circuit in fused ignition switch output circuit (White/Black wire) to leak detection pump. White/Black wire goes from leak detection pump to power distribution center, and then to Positive Temperature Coefficient (PTC) No. 1 in junction block, located behind driver's side of instrument panel, to the left of steering column. The PTC receives voltage when ignition is on. Once open circuit is repaired, perform TEST VER-5A.
    NOTE: The PTC is a specified amperage solid-state circuit breaker located in junction box. The PTC may reset when all current is removed from PTC for approximately 20 seconds.
  13. Turn ignition off. Disconnect connectors at Powertrain Control Module (PCM). The PCM is located between driver's side front fender and power distribution center, near battery.
  14. Using ohmmeter, check resistance between terminal No. 2 (White/Dark Green wire) on connector for leak detection pump and PCM connector terminal No. 77 (White/Dark Green wire). If resistance is less than 5 ohms, go to next step. If resistance is 5 ohms or more, repair open circuit in White/Dark Green wire between PCM and leak detection pump. Perform TEST VER-5A.
  15. Using ohmmeter, check resistance between ground and PCM connector terminal No. 77 (White/Dark Green wire). If resistance is less than 5 ohms, repair short to ground in White/Dark Green wire between PCM and leak detection pump. Perform TEST VER-5A. If resistance is 5 ohms or more, go to next step.
  16. Reinstall connector on leak detection pump. Turn ignition on. Using voltmeter, check voltage at PCM connector terminal No. 77 (White/Dark Green wire). If voltage is more than 10 volts, replace PCM. Perform TEST VER-5A. If voltage is 10 volts or less, replace leak detection pump. Perform TEST VER-5A.
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