Page 1 of 13 DIAGNOSTIC CHARTS NOTE: The following flow charts and schematics are courtesy of General Motors Corp. DIAGNOSTIC CHARTS Malfunction (1) Chart No. No Malfunction Indicator Lamp (MIL) (2) A1-1 MIL On Steady, Does Not Flash DTC 12 Or Any DTCs (2) A1-2 Engine Cranks But Will Not Start A1-3 Fuel Injector Circuit Check (Engine No-Start) A1-5 Fuel System (Fuel Pump Relay Check) A1-7A Fuel System (Fuel Pressure Check) A1-7B (1) Before using diagnostic charts, perform appropriate On-Board Diagnostic (OBD) System Check chart to determine starting point. See TESTS W/CODES - 1.6L article. (2) See TESTS W/CODES - 1.6L article. CHART A1-3, ENGINE CRANKS BUT WILL NOT RUN When ignition switch is turned to ON or START position, voltage is applied to ignition coil and ignitor. When ignitor receives an ignition signal from ECM, it toggles ignition coil primary coil windings ON and OFF. By toggling windings ON and OFF, a high voltage is produced in secondary coil windings. This induced voltage is then applied through distributor cap to each spark plug. NOTE: Test numbers refer to numbers on diagnostic chart. 1. 2. Checks for spark at distributor cap. Checks for faulty spark plug wires or misadjusted signal rotor air gap. Diagnostic Aids Water or foreign material in fuel can cause a no-start or a lack of power condition. Low fuel pressure, a restricted fuel filter, or fuel injectors may cause a no-start condition. Refer to CHART A1-5 for fuel injector circuit test. Check power supply to ECM for correct voltage. An intermittent may be caused by a poor connection, rubbed-through wire insulation, or a wire broken inside insulation. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal-to-wire connections before replacing components.
Page 2 of 13 Fig. 3: Chart A1-3 Schematic (Prizm - 1.6L VIN 6) Engine Cranks But Will Not Run
Page 3 of 13 Fig. 4: Chart A1-3 Diagnostic Flow Chart (Prizm - 1.6L VIN 6) Engine Cranks But Will Not Run CHART A1-5, FUEL INJECTOR CIRCUIT CHECK (ENGINE NO-START) When ignition switch is turned to ON or START position (engine running), ECM will energize/deenergize fuel injector coil. With coil energized, a plunger is activated, allowing pressurized fuel to be sprayed through fuel injectors into combustion chamber where it is mixed with air from intake manifold, thus creating proper air/fuel mixture needed for combustion. NOTE: Test numbers refer to numbers on diagnostic chart. 1. Checks if ECM is controlling ground path to fuel injectors.
Page 4 of 13 2. Checks resistance of fuel injectors. 3. Checks for open or short to ground in Black or Black/Red wire between fuel injectors and ECM, or for faulty fuel injectors or ECM. Diagnostic Aids Fuel spray may exist at fuel injectors, but it may not be enough to start engine. If fuel injectors and their circuits are okay, and fuel spray is detected, fuel injector nozzle may be partly blocked or restricted. See CHART A1-7A for circuit opening relay check. An intermittent may be caused by a poor connection, rubbed-through wire insulation, or a wire broken inside insulation. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal-to-wire connections before replacing components. Fig. 5: Chart A1-5 Schematic (Prizm - 1.6L VIN 6) Fuel Injector Circuit Check - Engine No- Start
Page 5 of 13 Fig. 6: Chart A1-5 Diagnostic Flow (Prizm - 1.6L VIN 6) Fuel Injector Circuit Check - Engine No-Start CHART A1-7A, FUEL SYSTEM DIAGNOSIS (CKT OPENING RELAY CHECK) When ignition switch is in START position, circuit opening relay will be energized to allow fuel pump to operate and pressurize system. Fuel pump will continue to operate if ECM receives an ignition signal when engine starts. Fuel pump operates as long as circuit opening relay is energized by ECM. When circuit opening relay is de-energized, fuel pump will stop operating. NOTE: Test numbers refer to numbers on diagnostic chart. 1. Checks for normal fuel pump operation. Checks if fuel pump will run when DLC terminals B+ and FP are jumpered 2. together. 3. Checks fuel pump operation while ignition signal is present at ECM. 4. Checks for an open in Black/Red wire to circuit opening relay.
Page 6 of 13 5. Checks for an open in Black/Red wire to DLC. 6. Checks for an open Blue/Black or Green/Red wire, a faulty ECM, or a faulty circuit opening relay. 7. Checks for open White/Black or Blue/Black wire, or faulty fuel pump. Diagnostic Aids A restricted or leaking fuel feed pipe or hose will cause an engine cranks but will not run condition. Check fuel sender assembly connections inside fuel tank for poor connection. See CHART A1-7B for fuel pressure test. An intermittent may be caused by a poor connection, rubbed-through wire insulation, or a wire broken inside insulation. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal-to-wire connections before replacing components. Fig. 7: Chart A1-7A Schematic (Prizm - 1.6L VIN 6) Fuel System Diagnosis - Circuit Opening Relay Check
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Page 9 of 13 Fig. 8: Chart A1-7A Diagnostic Flow Chart (Prizm - 1.6L VIN 6) Fuel System Diagnosis - Circuit Opening Relay Check CHART A1-7B, FUEL SYSTEM DIAGNOSIS (FUEL PRESSURE CHECK) When ignition switch is turned to START position, circuit opening relay will be energized to allow fuel pump to operate and pressurize system. Fuel pump will continue to operate if ECM receives an ignition signal when engine starts. Fuel pump operates as long as circuit opening relay is energized by ECM. When circuit opening relay is de-energized, fuel pump will stop operating. Fuel pump delivers fuel to fuel rail where pressure is maintained by fuel pressure regulator at 41 psi (2.9 kg/cm 2 ) more than pressure inside intake manifold. Excess fuel is returned to fuel tank through a return pipe and hoses. NOTE: Test numbers refer to numbers on diagnostic chart. 1. 2. 3. 4. 5. 6. Measures fuel pressure with ignition switch in ON position. Determines if fuel pressure is normal. Checks for leaking fuel pressure regulator. Checks for plugged fuel injectors. Checks for leaking fuel injectors or a leaking fuel pump. Checks for a leaking fuel pressure regulator or fuel pump Diagnostic Aids Check for leakage around all fuel hose/pipe connections. A plugged fuel injector could be the cause of a hard/no-start condition or loss of power/poor fuel economy. If fuel spray and pressure is normal, refer to TESTS W/O CODES - 1.6L article for mechanical checks and inspections.
Page 10 of 13 Fig. 9: Chart A1-7B Schematic (Prizm - 1.6L VIN 6) Fuel System Diagnosis - Fuel Pressure Check
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Page 13 of 13 Fig. 10: Chart A1-7B Diagnostic Flow Chart (Prizm - 1.6L VIN 6) Fuel System Diagnosis - Fuel Pressure Check 2008 Mitchell Repair Information Co., LLC.