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Home >> Jeep >> 1996 >> Grand Cherokee Limited, 5.2 Y >> Repair and Diagnosis >> External Pages >> Different car >> Section 180 (Engine Controls - Tests W/Codes - 4.0L) >> Self-Diagnostic Tests >> Test TC-38A - EVAP Solenoid Circuit (DTC 31)

Test TC-38A - EVAP Solenoid Circuit (DTC 31)

WARNING: This page is about a different car, the 1995 Jeep Wrangler, 1995 Jeep Grand Cherokee, and 1995 Jeep Cherokee. However, it is still accessible from the selected car via links, so may be relevant.
NOTE: Perform TEST TC-1A  before proceeding with this test. For connector terminal identification, see CONNECTOR IDENTIFICATION  at beginning of article. For wiring diagrams, see WIRING DIAGRAMS  at the end of this article. Perform TEST VER-2A  after each repair.
  1. Using scan tool, erase trouble codes. Using scan tool, actuate duty cycle purge EVAP solenoid. Using scan tool, read trouble codes. If scan tool does not display EVAP SOLENOID CIRCUIT, go to next step. If scan tool displays EVAP SOLENOID CIRCUIT, go to step 5).
  2. Condition required to set trouble code is not present at this time. EVAP SOLENOID CIRCUIT trouble code set when an open or short is detected in EVAP solenoid circuit. When de-energized, vacuum valve routes manifold vacuum to a vacuum-operated valve on evaporative emissions canister to open it. With vacuum valve opened, throttle body and/or manifold vacuum is used to purge fuel vapors from evaporative canister. EVAP solenoid coil has a resistance of 45 ohms and it requires 8 volts for solenoid to pull in and it will remain pulled in above 1.5 volts. Possible causes: open or shorted EVAP solenoid control circuit, open fused ignition switch output circuit, open or shorted solenoid control coil, PCM failure, or defective or damaged connector terminals or wires. Go to next step.
  3. Inspect all related wiring and connectors and repair as necessary. If no problems were found with wiring and connectors, go to next step.
  4. Using scan tool, continue running EVAP solenoid actuation test and read trouble codes. While monitoring scan tool for trouble codes, wiggle wiring harness between PCM and EVAP solenoid. If EVAP SOLENOID CIRCUIT, trouble code message resets, repair wiring where wiggling harness caused code to reset. If EVAP SOLENOID CIRCUIT trouble code message does not reset, see INACTIVE DTC CONDITION  in this article. Test is complete.
  5. Turn ignition off and disconnect EVAP solenoid connector and ensure connector is clean and not damaged. Turn ignition on. Using scan tool in voltmeter mode, check fused ignition switch output circuit voltage at EVAP solenoid connector terminal No. 1 (Dark Blue wire). If voltage is more than 10 volts, go to next step. If voltage is less than 10 volts, go to TEST TC-38B  .
  6. Turn ignition off. Disconnect PCM 60-pin connector and ensure connector is clean and not damaged. Using an external ohmmeter, check resistance of EVAP solenoid control circuit (Pink/Black wire) between PCM 60-pin connector terminal No. 52 and EVAP solenoid connector terminal No. 2. If resistance is less than 5 ohms, go to next step. If resistance is more than 5 ohms, repair open in EVAP solenoid control circuit.
  7. Using scan tool in ohmmeter mode, check resistance of EVAP solenoid control circuit (Pink/Black wire) at PCM 60-pin connector terminal No. 52. If resistance is more than 5 ohms, go to next step. If resistance is less than 5 ohms, repair short to ground in EVAP solenoid control circuit.
  8. Turn ignition off. Reconnect EVAP solenoid connector. Turn ignition on. Using scan tool in voltmeter mode, check EVAP solenoid control circuit (Pink/Black wire) voltage at PCM 60-pin connector terminal No. 52. If voltage is less than 10 volts, replace EVAP solenoid. If voltage is more than 10 volts, replace PCM.
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