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Home >> Ford >> 1988 >> Bronco II 4WD, Standard, M5OD-R1 >> Repair and Diagnosis >> Engine Performance >> System >> EEC-IV CEC System >> Quick Test >> Test D4 - Canister Purge (CANP) Check

Test D4 - Canister Purge (CANP) Check

NOTE: Perform this test when Service Code 85 is displayed during QUICK TESTS or when directed here by other test procedures.
Fig 1: Canister Purge (CANP) Circuit
G72367
  1. Checking System Function  - Enter OUTPUT STATE CHECK; see OUTPUT STATE CHECK  under QUICK TEST DIAGNOSTIC AIDS. Use only DVOM, not diagnostic tester, for this step. Turn key off and wait 10 seconds. Set DVOM on 20-volt scale. Connect DVOM negative test lead to STO and positive test lead to positive battery terminal. Using jumper wire, connect STI circuit to signal return at SELF-TEST connector. Perform KEY ON/ENGINE OFF (KOEO) SELF-TEST  until end of CONTINUOUS SELF-TEST codes (DVOM reads zero volts). Depress and release throttle. DVOM should change to a high voltage reading. If reading did not change, depress throttle to WOT and release. If STO voltage does not go high, go to TEST D16  , step 1). Leave test equipment hooked up. If reading changed, remain in OUTPUT STATE CHECK and go to next step.
  2. Checking Solenoid Electrical Function  - With KOEO, set DVOM on 20-volt scale. Disconnect CANP solenoid. Connect DVOM positive test lead to VPWR circuit and negative test lead to CANP output circuit on harness connector. While observing DVOM, depress and release throttle several times to cycle output on and off. If CANP circuit does not cycle on and off, remove jumper wire and go to step 6). If CANP circuit cycles, go to next step.
  3. Checking Solenoid For Vacuum Leaks  - Turn key on. Leave CANP solenoid disconnected. Disconnect vacuum hose from canister purge solenoid on PCV side. Apply 16 in. Hg vacuum to CANP solenoid. If CANP solenoid does not hold vacuum for 20 seconds, replace it and repeat QUICK TEST  . If fault is still present, service fuel evaporation system. If CANP holds vacuum for 20 seconds, leave vacuum pump attached and go to next step.
  4. Checking Solenoid Mechanical Operation  - While still in OUTPUT STATE CHECK, turn CANP circuit off (no voltage). Reconnect CANP solenoid connector. Apply 16 in. Hg vacuum to CANP solenoid as in step 3). Depress and release throttle. If vacuum is released, remove jumper wire from STI and go to next step. If vacuum is not released, replace CANP solenoid and repeat QUICK TEST  .
  5. Checking Vacuum Supply  - Disconnect vacuum hose from canister purge solenoid on PVC side. Start engine. If vacuum is present at vacuum hose, EEC system is okay. Check fuel system. If vacuum is not present at hose, check vacuum hose for proper routing, kinks, or blockage, If okay, check engine for cause of low vacuum.
  6. Measuring Solenoid Resistance  - Turn key off and wait 10 seconds. Set DVOM on 200-ohm scale. Disconnect CANP solenoid connector and measure solenoid resistance. If reading is between 40-90 ohms, go to next step. If reading is incorrect, replace CANP solenoid and repeat QUICK TEST  .
  7. Checking Voltage of VPWR Circuit  - Turn key off and wait 10 seconds. Set DVOM on 20-volt scale. Measure voltage between VPWR circuit at CANP solenoid harness connector and battery negative terminal. If reading is 10.5 volts or greater, go to next step. If reading is less than 10.5 volts, repair open in circuit and repeat QUICK TEST  .
  8. Checking Continuity of CANP Circuit  - Turn key off and wait 10 seconds. Disconnect ECA 60-pin connector. Inspect connector for damaged pins, corrosion, or loose wires. Repair if necessary. Connect breakout box, leaving ECA disconnected. Set DVOM on 200-ohm scale. Measure resistance between Test Pin No. 31 (No. 35 for 1.9L CFI, No. 32 for 1.9L MPFI engines) and CANP harness connector. If reading is less than 5 ohms, go to next step. If reading is 5 ohms or more, repair open circuit and repeat QUICK TEST  .
  9. Checking For Short to Ground  - Turn key off and wait 10 seconds. Install breakout box, leaving ECA disconnected. Set DVOM on 200K-ohm scale and disconnect CANP solenoid. Measure resistance between Test Pin No. 31 (No. 35 for 1.9L CFI, No. 32 for 1.9L MPFI engines) and Test Pins No. 40, 46, and 60. If all readings are 10K ohms or more, go to next step. If any reading is less than 10K ohms, repair short to ground and repeat QUICK TEST  .
  10. Checking For Short to Power  - Turn key off and wait 10 seconds. Install breakout box, leaving ECA disconnected. Set DVOM on 200K-ohm scale and disconnect CANP solenoid. Measure resistance between Test Pin No. 31 (No. 35 for 1.9L CFI, No. 32 for 1.9L MPFI engines) and Test Pins No. 37 and 57. If all reading are 10K ohms or more, remove breakout box. Replace ECA and repeat QUICK TEST  . If any reading is less than 10K ohms, repair short to power and repeat QUICK TEST. If code is repeated, replace ECA and repeat QUICK TEST.
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