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Air Conditioning Signal: 3.5RL

  1. Turn ignition off. Disconnect radiator fan control unit Black 12-pin connector located under front passenger's footrest, on main wire harness. Turn ignition on. Measure voltage by backprobing between PCM 26-pin connector "A" terminal No. 26 (Brown/Black wire) and PCM 12-pin connector "C" 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 else engine will not start.
  2. Turn ignition off. Disconnect PCM 12-pin connector "C". Check continuity between ground and PCM 12-pin harness connector "C" terminal No. 2 (Pink wire). If continuity exists, repair short circuit in Pink wire between PCM harness connector "C" terminal No. 2 and radiator fan control unit. If continuity does not exist, substitute a known-good PCM from donor vehicle, then recheck. Cut temporary key from a non-immobilizer key blank and tape donor vehicle key to it backwards in order to deactivate immobilizer system during testing. If voltage measured between PCM 26-pin connector "A" terminal No. 26 (Brown/Black wire) and PCM 12-pin connector "C" terminal No. 2 (Pink wire) is now battery voltage, replace original PCM. If voltage is not as specified, recheck A/C system operation. See appropriate AUTOMATIC A/C-HEATER SYSTEMS article in AIR CONDITIONING & HEATING.
  3. Turn ignition off. Reconnect radiator fan control unit connector. Turn ignition on. Using a jumper wire, momentarily backprobe PCM 26-pin connector "A" terminals No. 8 (Red/White wire) and 26 (Brown/Black wire). Repeat 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, backprobe A/C clutch relay connector terminal No. 4 (Red/White wire) to ground. Repeat several times. If A/C clutch clicks, repair open in Red/White wire between PCM 26-pin connector "A" terminal No. 8 and A/C clutch relay. If A/C clutch does not click, other A/C problems exist. See appropriate AUTOMATIC A/C-HEATER SYSTEMS article in AIR CONDITIONING & HEATING.
  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 by backprobing between PCM 26-pin connector "A" terminal No. 26 (Brown/Black wire) and PCM 12-pin connector "C" 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 from donor vehicle, then recheck. Cut temporary key from a non-immobilizer key blank and tape donor vehicle key to it backwards in order to deactivate immobilizer system during testing. If symptom or indication goes away, replace original PCM. If not, recheck A/C system operation. See appropriate AUTOMATIC A/C-HEATER SYSTEMS article in AIR CONDITIONING & HEATING.
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