1997 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 terminal A9 and terminal C5. See Figure. If battery voltage exists, go to step 3). If specified voltage does not exist, go to next step.
  2. Turn ignition off. Disconnect PCM connector "C". Check for continuity between ground and PCM connector terminal C5. If continuity exists, repair short in wire between PCM connector and A/C pressure switch. See WIRING DIAGRAMS article. If continuity does not exist, substitute a known good PCM, then recheck for voltage. Repeat step 1). If specified voltage now exists, replace original PCM. If specified voltage still does not exist, inspect A/C system. See the A/C-HEATER SYSTEM - MANUAL article in the AIR CONDITIONING & HEAT section.
  3. Turn ignition off. Reconnect A/C pressure switch and A/C diode connectors. Turn ignition on. Using a fused jumper wire, momentarily connect PCM connector terminal A9 and terminal 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 a fused 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 . If A/C compressor clutch makes a clicking sound, repair open in wire between A/C clutch relay and PCM connector terminal A17. See WIRING DIAGRAMS article. If A/C compressor clutch does not make a clicking sound, inspect A/C system. See the A/C-HEATER SYSTEM - MANUAL article in the AIR CONDITIONING & HEAT section.
  5. Start engine. Turn A/C and blower motor switches on. If A/C operates, A/C signal is okay. If A/C does not operate, measure voltage between PCM connector terminal A9 and terminal C5. See Figure. 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 A/C switch and PCM connector terminal C5. See WIRING DIAGRAMS article.
    A/C SIGNAL COMPONENT LOCATIONS

    A/C Component Location
    Clutch Relay Left front corner of engine compartment next to condenser fan relay
    Diode Behind glove box, taped to harness near 20-pin Red junction connector
    Pressure Switch Lower right front corner of engine compartment
    Fig 1: Identifying A/C Clutch Relay Connector
    G96E09620Courtesy of AMERICAN HONDA MOTOR CO., INC.
Factory Service Tools

Use the Manual With the Right Hardware

Pair factory procedures with proven DIY tools so the instructions are easier to execute.

Disclosure: Verified tool recommendations may earn an affiliate commission at no cost to you.

Shop Manual-Ready ToolsCompare Repair QuoteQuote Shield Pro

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.

Rather have a pro handle this?

A certified mobile mechanic comes to your home or office. They bring the tools, you stay comfortable. No tow truck, no waiting room, no surprises.

Comes to youSame-day available12-month warranty
Get a Free Quote

No obligation. See pricing before you book.