Test TC-187A - EVAP Leak Monitor Pinched Hose

NOTE: For connector terminal ID, see CONNECTOR IDENTIFICATION Directory. For wiring diagram, see WIRING DIAGRAMS article.

CAUTION: When performing test procedures keep all 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 the fumes. Wear safety glasses when performing test procedures. If vehicle is not being tested on a hoist, ensure parking brake is applied and drive wheels are blocked before performing test procedures.

To properly diagnose this trouble code, Miller Tool Kit (6872A) is necessary. Perform evaporative system pressure pump self-test specified on cover of tool kit.
Turn ignition off. Connect evaporative system pressure pump supply hose to Leak Detection Pump (LDP) EVAP system test port. See Figure. Set pressure hold to OPEN position and set vent to CLOSED position. Turn pump timer on. Tee an auxiliary vacuum pump to EVAP system test port. Using auxiliary vacuum pump, apply 18 in. of water vacuum to LDP. If LDP holds vacuum, go to next step. If the LDP does not hold vacuum, repair leaking LDP vacuum supply line. Perform TEST VER-5A.
Turn ignition on. Using scan tool, actuate LDP solenoid. Observe vacuum gauge. If vacuum dropped when LDP solenoid was actuated, go to next step. If vacuum did not drop when LDP solenoid was actuated, replace LDP. Perform TEST VER-5A.
Using auxiliary vacuum pump, raise vacuum to 18 in. of water vacuum. When pressure on Miller Tool Kit (6872) is more than 14 in. of water vacuum, remove gas cap. If pressure dropped when gas cap was removed, go to step 7). If pressure did not drop when gas cap was removed, note pressure reading. Go to next step.
Disconnect fuel tank vent line at EVAP canister. EVAP canister is located next to Leak Detection Pump (LDP). LDP is located under right front headlight assembly. To access LDP, remove right front headlight assembly. Go to next step.
If pressure dropped when vent line at EVAP canister was removed, repair obstruction in vent line between fuel tank and EVAP canister. Perform TEST VER-5A. If pressure did not drop when vent line at EVAP canister was removed, go to TEST TC-187B.
Reinstall gas cap. Allow Miller Tool Kit (6872) pump to build pressure to at least 14 in. of water vacuum. Disconnect pressure hose from LDP. If pressure dropped when pressure hose was disconnected from LDP, go to TEST TC-187C. If pressure did not drop when pressure hose was disconnected from LDP, go to next step.
Disconnect LDP pressure hose from EVAP canister. If pressure dropped when hose was disconnected from EVAP canister, replace LDP pressure hose. Perform TEST VER-5A. If pressure did not drop when hose was disconnected from EVAP canister, replace EVAP canister. Perform TEST VER-5A.