Schematic Reference: Engine Controls Schematics
When the ignition switch is turned to the ON or START positions, voltage is applied to the ignition coil and ignition control (IC) module (Igniter). When the IC module receives the command from the powertrain control module (PCM), the primary coil windings of the ignition coil are toggled ON and OFF. By toggling the windings ON and OFF, a high voltage is produced in the secondary coil windings. The induced high voltage is forced to find a ground path through the rotor and distributor cap to each secondary spark plug wire and spark plug.
Check for any of the following conditions:
• | Check the battery condition and the engine cranking speed. The engine will not start and improper diagnosis may occur if the starting system is not operating to necessary levels. Refer to Starting System check in Engine Electrical. |
• | Water or foreign material can cause a no start during freezing weather. The engine may start after 5 or 6 minutes in a heated shop. The malfunction may not recur until the vehicle is parked overnight in freezing temperatures. |
• | Fouled or damaged spark plugs may cause an Engine Cranks But Will Not Run condition. Refer to Spark Plug Visual Diagnosis in Engine Electrical. |
• | A vehicle that starts and runs after being brought to the shop for an Engine Cranks But Will Not Run complaint, may have an ignition system that is susceptible to moisture. Spray water on the ignition system components and wiring in order to check for an engine miss or stall. |
• | Check for a malfunctioning EFI relay. A faulty EFI relay can cause no MIL and an engine that cranks but will not run. |
An intermittent malfunction may be caused by a problem in the ignition system electrical circuit. Inspect the wiring harness and components for any of the following conditions:
• | Backed out terminals. |
• | Improper mating of terminals. |
• | Broken electrical connector locks. |
• | Improperly formed or damaged terminals. |
• | Faulty terminal to wiring connections. |
• | Physical damage to the wiring harness. |
• | Broken conductor inside the wire insulation. |
• | Corrosion of electrical connections, splices, or terminals. |
The numbers below refer to the step numbers in the diagnostic table.
The Powertrain OBD System Check prompts the technician to complete some basic checks and stores the freeze frame data on the scan tool if applicable. This creates an electronic copy of the data taken when the fault occurred. The information is then stored in the scan tool for later reference.
The PCM relies on the CMP sensor for engine reference. Without engine reference signals there is no spark and no fuel injector pulse.
If there is a fault in the primary ignition system circuits or the ignition control module, DTC P1300 sets.
This step checks the ECT sensorr for a faulty signal. A faulty sensor input to the PCM may cause a fueling condition that results in a no start.
This step checks the TP sensor for a faulty signal. A faulty sensor input to the PCM may cause a fueling condition that results in a no start.
This step checks the MAP sensor for a faulty signal. A faulty sensor input to the PCM may cause a fueling condition that results in a no start.
This step checks for adequate secondary ignition voltage at the spark plugs.
This step checks to see if fuel system pressure is within specifications with the ignition ON and the fuel pump running. The fuel pump may be operated with the scan tool Output Control feature when the fuel level is greater than 20%.
Step | Action | Values | Yes | No | ||||||||||||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Did you perform the Powertrain On-Board Diagnostic System Check? | -- | |||||||||||||||||||||
Check for DTCs with a scan tool. Is DTC P0335 or P0340 set? | -- | Go to DTC P0335 Crankshaft Position (CKP) Sensor Circuitor DTC P0340 Camshaft Position (CMP) Sensor Circuit | ||||||||||||||||||||
Is DTC P1300 set? | -- | |||||||||||||||||||||
Is the coolant temperature displayed on the scan tool near the actual coolant temperature? | -- | Go to DTC P0116 Engine Coolant Temperature (ECT) Sensor Performance | ||||||||||||||||||||
Observe the TP sensor parameter on a scan tool with the throttle closed. Is the throttle position opening displayed on the scan tool within the specified value? | 0-23% | |||||||||||||||||||||
Was the kPa reading of both vehicles within 2kPa of each other? | -- | Go to DTC P0106 Manifold Absolute Pressure (MAP) System Performance | ||||||||||||||||||||
Did each spark plug wire have a good crisp blue spark while cranking the engine? | -- | |||||||||||||||||||||
Important: In order to obtain maximum fuel pressure it may be necessary to cycle the ignition ON to OFF to ON more than once. Is the fuel pressure indicated within the specified values? | 265 to 304 kPa (38 to 44 psi) | |||||||||||||||||||||
9 |
Did the fuel pressure gauge indicate any pressure greater than the specified value? | 0 to 7 kPa (0 to 1.0 psi) | Go to Fuel System Diagnosis | |||||||||||||||||||
10 |
Was a repair necessary? | -- | ||||||||||||||||||||
11 |
Did any of the spark plugs need replacement? | -- | ||||||||||||||||||||
12 |
Did the injector test lamp flash for each injector while cranking the engine? | -- | ||||||||||||||||||||
13 | Check for faulty fuel injectors. Refer to Fuel Injector Solenoid Coil Test - Engine Coolant Temperature Between 10-35 Degrees C (50-95 Degrees F) and Fuel Injector Balance Test. Was a faulty fuel injector found and replaced? | -- | ||||||||||||||||||||
14 | Measure the resistance of each spark plug wire. Is the resistance within the specified values? | 3.0k to 6.7k ohms per ft. | ||||||||||||||||||||
15 |
Was the resistance of both ignition coil circuits within the specified values? | 0.36 to 0.55 ohms at -10 to 50°C (14 to 104°F)9.0k to 15.4k ohms at -10 to 50°C (14 to 104°F) | ||||||||||||||||||||
16 |
Was a repair necessary? | -- | ||||||||||||||||||||
17 | Replace the ignition coil. Refer to Ignition Coil Replacement in Engine Controls. Is the action complete? | -- | -- | |||||||||||||||||||
18 |
Was a basic engine mechanical problem found and repaired? | -- | Go to Diagnostic Aids | |||||||||||||||||||
19 | Replace any faulty spark plug wires. Is the action complete? | -- | -- | |||||||||||||||||||
20 |
Does the engine start and continue to run? | -- | -- | |||||||||||||||||||
21 |
Are any DTCs displayed? | -- | System OK | Go to the applicable Diagnostic table |