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Air Conditioning Signal

  1. Turn ignition off. Disconnect radiator fan control unit 12-pin connector located under right side of dash, behind PCM cover. Turn ignition on. Measure voltage between PCM 26-pin connector terminal No. 26 (Brown/Black wire) and PCM 12-pin connector terminal No. 2 (Pink wire). See Figure . If battery voltage exists, go to step 3). If battery voltage does not exist, go to next step.
    NOTE: When substituting PCM, immobilizer code must be rewritten to replacement PCM using Honda PGM tester or engine will not start.
  2. Turn ignition off. Disconnect PCM 12-pin connector. Check continuity between ground and PCM 12-pin connector terminal No. 2 (Pink wire). If continuity exists, repair short in Pink wire between PCM and radiator fan control unit. If continuity does not exist, substitute a known good PCM, then recheck. If symptom or indication goes away, replace original PCM. Ensure A/C is operating properly. See the A/C-HEATER SYSTEM - AUTOMATIC article in the AIR CONDITIONING & HEAT section.
  3. Turn ignition off. Reconnect radiator fan control unit connector. Turn ignition on. Using a jumper wire, momentarily connect PCM 26-pin connector terminals No. 8 (Red/White wire) and No. 26 (Brown/Black wire), several times. See Figure . If A/C compressor clutch clicks, go to step 5). If A/C clutch does not click, go to next step.
  4. Locate A/C clutch relay in underhood relay box "A" at left front of engine compartment, between battery and upper radiator hose. Using a jumper wire, connect A/C clutch relay connector terminal No. 4 (Red/White wire) to ground, several times. If A/C clutch clicks, repair open in Red/White wire between PCM and A/C clutch relay. If A/C clutch does not click, other A/C problems exist. See the A/C-HEATER SYSTEM - AUTOMATIC article in the AIR CONDITIONING & HEAT section.
  5. Start engine. Turn blower and A/C switches on. If A/C operates,A/C signal is okay. If A/C does not operate, measure voltage between PCM 26-pin connector terminal No. 26 (Brown/Black wire) and PCM 12-pin connector terminal No. 2 (Pink wire). See Figure .
  6. If voltage is one volt or more, repair open in Pink wire between PCM 12-pin connector terminal No. 2 and radiator fan control unit. If voltage is less than one volt, substitute a known good PCM, then recheck. If symptom or indication goes away, replace original PCM.
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