Suzuki Samurai Heated O2 Sensor Wiring Diagram - ECM B15/B20 & Code 13 Notes

This scanned page is an oxygen sensor (O2 sensor) wiring diagram and diagnostic note page from a Suzuki service manual, uploaded to a 1986 Suzuki Samurai gallery. The diagram shows the ECM (1) and ECM coupler (2) connected via terminals B20 and B15 (with a Gr/Y wire noted) to the heated oxygen sensor. Two sensor variants are shown: item 3, the heated oxygen sensor for 1993 California-spec vehicles, and item 3-1, the heated oxygen sensor for other vehicles. Terminal-side views of both sensor couplers identify the sensor signal terminal, sensor ground terminal, and heater terminal(s). Item 4 is the coupler and item 5 indicates wiring to other sensors. The accompanying NOTE instructs the technician, before following the diagnostic flow chart, to verify that non-EFI systems are in good condition: air cleaner (clogged), vacuum leaks, spark plugs, high-tension cords, distributor rotor/cap, ignition timing, engine compression, and anything else affecting air/fuel mixture or combustion. It also states that if trouble code No. 13 appears together with another code, the other code has priority and should be corrected first. Finally, it requires use of a high-impedance (MΩ/V minimum) or digital voltmeter for accurate measurement. The reference to 1993 California-spec vehicles suggests this page is from an early-1990s EFI Suzuki manual rather than a 1986 model.