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Home >> Acura >> 1999 >> 2.3CL Automatic >> Repair and Diagnosis >> Engine Performance >> System >> Engine Controls - Self-Diagnostics >> Diagnostic Tests >> DTC P1456: EVAP Control System
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DTC P1456: EVAP Control System

  1. Ensure fuel filler cap is fully tightened and seal is okay. Replace as necessary. If fuel filler cap is okay, go to next step.
  2. Remove fuel filler cap. Turn ignition on. Measure voltage between PCM 32-pin connector terminal No. 29 (Light Blue wire) and PCM 31-pin connector terminal No. 18 (Green/Black wire). If about 2.5 volts are present, go to next step. If about 2.5 volts are not present, replace fuel tank pressure sensor.
  3. Turn ignition off. Disconnect hose between EVAP 2-way valve and fuel tank pressure sensor at 2-way valve end. Connect vacuum pump to disconnected hose. Turn ignition on. Measure voltage between PCM 32-pin connector terminal No. 29 (Light Blue wire) and PCM 31-pin connector terminal No. 18 (Green/Black wire) while carefully pumping vacuum one stroke at a time. Voltage should smoothly drop from about 2.5 volts down to about 1.5 volts. DO NOT apply vacuum when voltage drops to about 1.5 volts, or fuel tank pressure sensor may be damaged. If voltage drops to about 1.5 volts and holds, replace fuel tank pressure sensor. If voltage does not drop to about 1.5 volts and hold, fuel tank pressure sensor is okay. Go to next step.
  4. Disconnect vacuum hose from EVAP purge control solenoid valve. Connect vacuum pump to disconnected hose. Turn ignition on. Apply vacuum to hose. If EVAP purge control solenoid valve does not hold vacuum, go to next step. If EVAP purge control solenoid valve holds vacuum, go to step  7.
  5. Turn ignition off. Disconnect EVAP purge control solenoid valve 2-pin connector. Measure continuity between EVAP purge control solenoid valve 2-pin connector terminal No. 1 (Red/Yellow wire) and ground. If continuity is present, go to next step. If continuity is not present, replace EVAP purge control solenoid valve.
  6. Disconnect PCM 32-pin connector. Measure continuity between EVAP purge control solenoid valve 2-pin connector terminal No. 1 (Red/Yellow wire) and ground. If continuity is present, repair short circuit in Red/Yellow wire between PCM 32-pin connector terminal No. 6 and EVAP purge control solenoid valve connector terminal No. 1. If continuity is not present, replace PCM.
  7. Disconnect vacuum hose from EVAP 2-way valve. Connect vacuum hose to disconnect hose. Connect jumper wire between PCM 32-pin connector terminal No. 3 (Blue/Black wire) and ground. Turn ignition on. Apply vacuum to hose. If EVAP 2-way valve holds vacuum, go to next step. If EVAP 2-way valve does not hold vacuum, EVAP 2-way valve is okay. Go to step  10.
  8. Turn ignition off. Disconnect EVAP by-pass solenoid valve 2-pin connector. Measure continuity between EVAP by-pass solenoid valve 2-pin connector terminal No. 2 (Blue/Black wire) and ground. If continuity is present, go to next step. If continuity is not present, repair open circuit in Blue/Black wire between EVAP by-pass solenoid valve and PCM 32-pin connector terminal No. 3.
  9. Turn ignition on. Measure voltage between EVAP by-pass solenoid valve 2-pin connector terminal No. 1 (Black/Yellow wire) and ground. If battery voltage is present, replace EVAP by-pass solenoid valve and "O" rings. If battery voltage is not present, repair open circuit in Black/Yellow wire between EVAP by-pass solenoid valve connector terminal No. 1 and PCM 7.5-amp fuse No. 4.
  10. Disconnect vacuum hose from EVAP 3-way valve. Connect vacuum pump to hose. Turn ignition on. Apply vacuum to hose. If valve holds vacuum, go to next step. If valve does not hold vacuum, EVAP control canister vent shut valve is okay. Go to step  13.
  11. Turn ignition off. Disconnect EVAP control canister vent shut valve 2-pin connector. Measure continuity between EVAP control canister vent shut valve 2-pin connector terminal No. 2 (Orange/Green wire) and ground. If continuity is present, go to next step. If continuity is not present, replace EVAP control canister vent shut valve and "O" ring.
  12. Disconnect PCM 32-pin connector. Measure continuity between EVAP control canister vent shut valve 2-pin connector terminal No. 2 (Orange/Green wire) and ground. If continuity is present, repair short circuit in Orange/Green wire between PCM 32-pin connector terminal No. 4 and EVAP control canister vent shut valve connector terminal No. 2. If continuity is not present, replace PCM.
  13. Check vacuum hoses and connections at fuel tank, fuel fill cap, fuel fill pipe, EVAP 2-way valve, and fuel tank pressure sensor for leakage. Repair or replace as necessary. If components are okay, replace PCM.
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