1990 Suzuki SamuraiFACTORY OEM SERVICE PROCEDURE

EGR System Test (Federal Samurai)

  1. Before checking EGR system, ensure throttle position sensor, coolant temperature sensor and pressure sensor are operating correctly. See THROTTLE POSITION SENSOR, COOLANT (WATER) TEMPERATURE SENSOR and PRESSURE SENSOR under ENGINE SENSORS & SWITCHES  in this article.
  2. Ensure no 5th switch signal is applied to ECM. The ECM is located behind glove box. To check 5th switch signal, check for voltage at terminal A5 (Light Blue wire) of ECM. If voltage is present, check 5th switch circuit. See WIRING DIAGRAMS article.
  3. To check EGR system, place transmission in Neutral. Apply parking brake. With coolant temperature less than 127°F (53°C), start engine and operate at high RPM. EGR diaphragm should not move.
  4. Warm engine to normal operating temperature. Operate engine at high RPM. EGR valve diaphragm should move up during acceleration.
  5. If EGR valve does not operate as specified, check for misrouted, restricted, clogged or deteriorated vacuum hoses. If vacuum hoses are okay, check EGR valve and EGR modulator (backpressure transducer). See EGR VALVE  and EGR MODULATOR (BACKPRESSURE TRANSDUCER)  under EXHAUST GAS RECIRCULATION (EGR) in this article.
  6. If EGR valve and EGR modulator (backpressure transducer) are okay, check EGR Vacuum Switching Valve (VSV). See EGR VACUUM SWITCHING VALVE (VSV)  under EXHAUST GAS RECIRCULATION (EGR) in this article.
  7. If VSV is okay, check for open or short in wiring circuit. See Fig 1 . Check for defective connections at ECM and VSV. If connections are okay, check EFI main relay. See EFI MAIN RELAY under RELAYS & SOLENOIDS  in this article. If all components and wiring are okay, substitute ECM and recheck.
Fig 1: EGR Control System Wiring & Vacuum Diagram (Samurai)
G90G17398Courtesy of SUZUKI OF AMERICA CORP.
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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.