Symptom Troubleshooting - Engine - (MZI-3.7): Overview

Symptom Troubleshooting - Engine - (MZI-3.7): Overview Mazda CX-9 I

Scheme 1: SYMPTOM TROUBLESHOOTING WIRING DIAGRAM [MZI-3.7]

Scheme 4: FOREWORD [MZI-3.7]

When the customer reports a vehicle malfunction, check the malfunction indicator lamp (MIL) indication and diagnostic trouble code (DTC), then diagnose the malfunction according to the following flowchart: If a DTC exists, diagnose the applicable DTC inspection. See «DTC TABLE [MZI-3.7]»(/mazda/cx-9/i-2006-2012/remont/testing-diagnostics/#on-board-diagnostic-engine-controls-mzi-37). If no DTC exists and the MIL does not illuminate or flash, diagnose the applicable symptom troubleshooting. See «QUICK DIAGNOSTIC CHART [MZI-3.7]».

Main Relay Operation Inspection

Verify that the main relay clicks when the ignition switch is turned to ON position and off. If there is no operation sound, inspect the following: Main relay See «RELAY INSPECTION». Harness and connector between battery and main relay terminal A. Harness and connector between PCM terminal 1Q and main relay terminal E.

STEP	INSPECTION	RESULTS	ACTION
1	While cranking the engine, inspect for fuel injector operation sound at each cylinder using a soundscope. Is operation sound heard?	Yes	Fuel injector operation is normal.
1		No	All cylinders not heard: Go to the next step. Some cylinders not heard: Go to Step 3.
2	Perform main relay operation inspection. Is main relay operation normal?	Yes	Inspect the following: Fuel injector power system related wiring harness and connectors PCM connectors Fuel injector GND and related wiring harness and connectors
2		No	Repair or replace malfunctioning parts.
3	Switch fuel injector connector of not operating fuel injector with operating fuel injector. Is operation sound heard?	Yes	Go to the next step.
3		No	Replace the fuel injector.
4	Are wiring harness and connectors of not operation fuel injector normal? (Open or short)	Yes	Inspect PCM terminal voltage of fuel injector signal.
4		No	Repair or replace malfunctioning parts.

FUEL INJECTOR OPERATION INSPECTION CHART

Remove the fuel-filler cap.
Turn the ignition switch to the ON position.
Turn the fuel pump relay from off to on using the FP PID and inspect if the operation sound is heard. If no operation sounds is heard, proceed to next step.
Measure voltage at wiring harness side fuel pump connector terminal B. Specification B+ (Ignition switch at on) If the voltage is as specified, inspect the following: Fuel pump continuity Fuel pump GND Wiring harness between fuel pump relay and PCM terminal 1V If not as specified, inspect the following: Fuel pump relay Wiring harness connector (Main relay-fuel pump relay-fuel pump)