1996 Isuzu Oasis LSFACTORY OEM SERVICE PROCEDURE

Air Conditioning Signal

NOTE: This signal informs the PCM that there is a demand for cooling from the A/C system.
  1. Turn ignition off. Disconnect A/C pressure switch and A/C diode. See A/C SIGNAL COMPONENT LOCATIONS  . Turn ignition on. Measure voltage between PCM connector terminals A9 and C5. See Figure . If battery voltage exists, go to step 3). If battery voltage does not exist, turn ignition off and disconnect PCM connector "C".
  2. Check for continuity between ground and PCM connector terminal C5. If continuity exists, repair short to ground in wire between PCM connector and A/C pressure switch. See WIRING DIAGRAMS  section. If continuity does not exist, substitute a known-good PCM. Repeat step 1). If battery voltage now exists, replace original PCM. If battery does not exist, inspect A/C system.
  3. Turn ignition off. Reconnect A/C pressure switch and A/C diode. Turn ignition on. Using jumper wire, momentarily connect PCM connector terminals A9 and A17 several times. See Figure . If A/C compressor clutch makes a clicking sound, go to step 5). If A/C compressor clutch does not make a clicking sound, go to next step.
  4. Using jumper wire, momentarily connect A/C clutch relay connector terminal No. 4 to ground several times. See Fig 1 . See A/C SIGNAL COMPONENT LOCATIONS table. If A/C compressor clutch makes a clicking sound, repair open in wire between PCM connector terminal A17 and A/C clutch relay. See WIRING DIAGRAMS  section. If A/C compressor clutch does not make a clicking sound, inspect A/C system.
  5. Start engine. Turn A/C and blower switches on. If A/C operates,A/C signal is okay. If A/C does not operate, measure voltage between PCM connector terminals A9 and C5. See Figure .
  6. If less than one volt exists, substitute known-good PCM and recheck. If symptom or indication goes away, replace original PCM. If not, inspect A/C system. If less than one volt is not present, repair open in wire between PCM connector terminals C5 and A/C switch. See WIRING DIAGRAMS  section.
A/C SIGNAL COMPONENT LOCATIONS

Application Location
A/C Clutch Relay Left front corner of engine compartment
A/C Diode Behind glove box, near 3-pin Yellow passenger's air bag connector
A/C Pressure Switch Lower right front corner of engine compartment
Fig 1: Identifying A/C Clutch Relay Connector (Oasis)
G96E09620Courtesy of AMERICAN HONDA MOTOR CO., INC.
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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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