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Diagnosis & Repair Procedure

NOTE: For better performance and results of this diagnostic procedure, usage of appropriate wiring diagram is recommended. See ENGINE PERFORMANCE in SYSTEM WIRING DIAGRAMS article in ELECTRICAL.
NOTE: Perform all voltage and resistance tests using a Digital Volt-Ohmmeter (DVOM) with a minimum 10-megohm input impedance, unless stated otherwise in test procedure. Use an ohmmeter to isolate wiring harness shorts or opens.
  1. If engine system check has been performed, go to next step. If engine system check has not been performed, perform A-4: ENGINE SYSTEM CHECK  under SYSTEM TESTS, then go to next step.
  2. Turn ignition switch to LOCK position. Disconnect HO2S-2 4-pim harness connector C62, located after warm-up three way catalytic converter. See Figure . Measure resistance between HO2S-2 harness connector terminals No. 3 and 4 (component side). See Figure . If resistance is 11.7-14.3 ohms, go to next step. If resistance is not 11.7-14.3 ohms, replace HO2S-2. See HEATED OXYGEN SENSORS NO. 1 & 2 under ENGINE SENSORS & SWITCHES in REMOVAL & INSTALLATION article. After repair, repeat DTC CONFIRMATION TEST  .
  3. Locate ECM 35-pin harness connector C61 under instrument panel, behind glove box. See Figure . Turn ignition switch to ON position. Backprobe and measure voltage between ground and ECM harness connector C61 terminal No. 3 (Pink/Green wire). See Figure . If voltage is 10-14 volts, go to next step. If voltage is not 10-14 volts, check Black/White wire and Pink/Green wire for open circuit or short to ground between ECM and HO2S-2. If open circuit or short to ground is found, repair as necessary and repeat DTC CONFIRMATION TEST  . If open circuit or short to ground is not found, substitute ECM with a known good unit and repeat DTC CONFIRMATION TEST  .
  4. Drive vehicle at 30-40 MPH for 2 minutes or more. Stop vehicle and let it idle. Backprobe and measure voltage between ground and ECM harness connector C61 terminal No. 3 (Pink/Green wire). See Figure . If voltage is 0-1 volt, problem is intermittent. See INTERMITTENTS in TROUBLE SHOOTING - NO CODES article. After repair, repeat DTC CONFIRMATION TEST  .If voltage is not 0-1 volt, check HO2S-2 connector terminals for corrosion or poor connection. If connector terminals are faulty, repair as necessary and repeat DTC CONFIRMATION TEST  . If connector terminals are okay, substitute ECM with a known good unit and repeat DTC CONFIRMATION TEST  .
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