1999 Acura Integra GS-R, 4D SedanFACTORY OEM SERVICE PROCEDURE

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. Backprobing, 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 harness 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 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 terminals No. 8 (Red/White wire) and No. 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 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, backprobing, 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. Ensure A/C is operating properly. See appropriate AUTOMATIC A/C-HEATER SYSTEMS article in AIR CONDITIONING & HEATING.
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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • • You smell fuel, burning insulation, or see smoke.
  • • Brakes feel soft, pull hard to one side, or make grinding noises.
  • • The engine overheats, stalls repeatedly, or misfires under load.
  • • You are missing required tools, torque specs, or safe lifting equipment.
  • • You are not confident in the next step or safety outcome.

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