Camry CNG Models
NOTE:
On Camry CNG models, fuel injectors are actuated by 150 volts for approximately 100 milliseconds when engine is first started. Voltage has been increased to 150 volts by voltage booster circuit incorporated into Engine Control Module (ECM).
- Check that wiring harness and electrical connectors for fuel injectors are properly connected. If wiring harness and electrical connectors for fuel injectors are properly connected, go to next step. If wiring harness and electrical connectors for fuel injectors are not properly connected, repair as necessary. Drive vehicle to confirm that no cylinders are misfiring.
- Check that vacuum hoses are properly connected and that no vacuum hoses are damaged. If vacuum hoses are properly connected and no vacuum hoses are damaged, go to next step. If vacuum hoses are not properly connected or vacuum hoses are damaged, repair as necessary. Drive vehicle to confirm that no cylinders are misfiring.
- Note which cylinder is misfiring. Check spark plug and for spark on misfiring cylinder. See SPARK TEST under IGNITION SYSTEMS in BASIC DIAGNOSTIC PROCEDURES - 4-CYLINDER article. If spark plug is okay and proper spark exist at misfiring cylinder, go to next step. If sparks plug is defective or proper spark does not exist at misfiring cylinder, replace components or repair ignition system as necessary.
- Remove glove box for access to ECM. For illustration of ECM location, see THEORY & OPERATION article. Note ECM electrical connector terminals. See Figure.
- Turn ignition on. Using voltmeter, check voltage between body ground and appropriate terminal at ECM electrical connector E7 for misfiring cylinder. See ECM TERMINAL #10 TO #40 IDENTIFICATION FOR FUEL INJECTORS table. These are the #10 to #40 terminals for fuel injectors at ECM. Voltage should be 9-14 volts. Using oscilloscope, check fuel injector signal wave pattern and fuel injector duration signal wave pattern with engine idling at appropriate terminal at ECM electrical connector E7 for misfiring cylinder. Fuel injector signal wave pattern and fuel injector duration signal wave pattern should be properly displayed with 100 millisecond intervals. See Fig 1. If voltage is not within specification, or fuel injector signal wave pattern or fuel injector duration signal wave pattern are not okay, go to next step. If voltage is within specification, and fuel injector signal wave pattern and fuel injector duration signal wave pattern are okay, go to step 9.ECM TERMINAL #10 TO #40 IDENTIFICATION FOR FUEL INJECTORS
Fuel Injector Location ECM Connector ECM Terminal No. (Wire Color) Cyl. No. 1 E7 6 (Black/White) Cyl. No. 2 E7 7 (Black/Red) Cyl. No. 3 E7 8 (Red) Cyl. No. 4 E7 9 (Orange) - Ensure ignition is on. Using voltmeter, check voltage between body ground and appropriate terminal at ECM electrical connector E7 for misfiring cylinder. See ECM TERMINAL #10+ TO #40+ IDENTIFICATION FOR FUEL INJECTORS table. These are the #10+ to #40+ terminals for fuel injectors at ECM. Voltage should be 9-14 volts. If voltage is within specification, go to next step. If voltage is not within specification, replace ECM.ECM TERMINAL #10+ TO #40+ IDENTIFICATION FOR FUEL INJECTORS
Fuel Injector Location ECM Connector ECM Terminal No. (Wire Color) Cyl. No. 1 E7 2 (Blue) Cyl. No. 2 E7 3 (Brown) Cyl. No. 3 E7 4 (Green) Cyl. No. 4 E7 5 (White) - Turn ignition off. Disconnect electrical connector at fuel injector on misfiring cylinder. Using ohmmeter, check resistance between electrical terminals on fuel injector. Resistance should be 1.40-2.00 ohms at 68°F (20°C). If resistance is within specification, reinstall electrical connector on fuel injector and go to next step. If resistance is not within specification, replace fuel injector.
- Check for open and short in wiring harness and connectors between fuel injector and ECM. See WIRING DIAGRAMS article. If wiring harness and electrical connectors are okay, test is complete. If wiring harness or electrical connector is defective, repair as necessary.
- Check operation of fuel rail fuel shutoff valve, fuel pressure regulator fuel shutoff valve and fuel tank fuel shutoff valve. See DTC P1190: FUEL PRESSURE REGULATOR MALFUNCTION in appropriate SELF-DIAGNOSTICS article. If all fuel shutoff valves operate properly, go to next step. If any fuel shutoff valve does not operate properly, replace or repair as necessary.
- Check fuel injector operation. See FUEL CONTROL under FUEL SYSTEMS. If fuel injector operates properly, go to next step. If fuel injector does not operate properly, replace fuel injector.
- Check EGR system operation by performing system check. See EXHAUST GAS RECIRCULATION SYSTEM under EMISSION SYSTEMS & SUB-SYSTEMS. If EGR system operates properly, go to next step. If EGR system does not operate properly, repair EGR system as necessary.
- Check Engine Coolant Temperature (ECT) sensor and Manifold Absolute Pressure (MAP) sensor. See ENGINE COOLANT TEMPERATURE SENSOR and MANIFOLD ABSOLUTE PRESSURE SENSOR under ENGINE SENSORS & SWITCHES. If ECT sensor and MAP sensor operate properly, go to next step. If ECT sensor or MAP sensor does not operate properly, replace as necessary.
- Check engine compression. See MECHANICAL INSPECTION under PRELIMINARY INSPECTION & ADJUSTMENTS in BASIC DIAGNOSTIC PROCEDURES - 4-CYLINDER article. If engine compression is within specification, go to next step. If engine compression is not within specification, repair engine as necessary.
- Check valve clearance. See VALVE CLEARANCE under ENGINE MECHANICAL in ON-VEHICLE ADJUSTMENTS - 4-CYLINDER article. If valve clearance is within specification, go to next step. If valve clearance is not within specification, adjust valve clearance as necessary.
- Check valve timing. See appropriate article in ENGINES. If valve timing is correct, test is complete. If valve timing is not correct, repair as necessary.
NOTE:
Fuel injectors are actuated by 150 volts for approximately 100 milliseconds when engine is first started. Voltage has been increased to 150 volts by voltage booster circuit incorporated into ECM.