Circuit Description
This engine is equipped with a distributorless ignition system called the electronic ignition (EI) system. The primary circuit of the EI system consists of 2 separate ignition coils, an electronic ignition control module (ICM) and a crankshaft position (CKP) sensor as well as the related connecting wires and the ignition control (IC) portion of the Powertrain Control Module (PCM). Each secondary circuit consists of the secondary winding of the coil, spark plug wires, and the spark plugs.
Important: The camshaft position (CMP) sensor is only used for a misfire detection and is not part of the ignition system.
Diagnostic Aids
Check for the following conditions:
| • | The Throttle Position (TP) sensor binding or sticking in wide open throttle position |
| • | The Throttle Position (TP) sensor for a shorted or open circuit |
| • | Water or foreign material in the fuel |
| • | Low compression (timing chain failure) |
| • | A slow responding EGR Valve |
Test Description
Number(s) below refer to the step number(s) on the Diagnostic Table.
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The Powertrain OBD System Check prompts the technician to complete some basic checks and store the freeze frame and failure records data on the scan tool if applicable. This creates an electronic copy of the data taken when the malfunction occurred. The information is then stored in the scan tool for later reference.
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Diagnosis of the DTCs that may be set could lead to the cause of the Cranks But Will Not Run condition.
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The PCM grounds will only cause a problem if all the grounds are not making a good connection. If a PCM ground problem is suspected, the most probable place to check is where all the grounds meet at the engine block.
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Locate and repair any shorts that may have caused the fuse to open before replacing the fuse.
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A TP sensor that reads too high may cause an incorrect fueling condition.
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An engine that has not been started should display ECT and IAT temperatures that are relatively close to each other. During the warmer weather, the IAT readings maybe slightly higher than the ECT readings.
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This step looks for a normal barometer reading and a change in MAP sensor values while cranking the engine. This step verifies the MAP sensor can detect the change in the manifold pressure that occurs while cranking the engine. Compare any questionable barometer readings with readings from another vehicle.
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While cranking the engine, the CKP Activity (7X reference) should increment to 255, then rollover to 0.
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If the scan tool loses serial data only while cranking the engine, then the ignition switch is not sending voltage to the PCM while in the crank position.
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Check for possible voltage loss to the PCM including the ignition switch itself.
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By testing for spark on all 4 plug wire leads, each ignition coil(s) ability to produced at least 25,000 volts is verified.
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The CKP sensor core is a magnet, therefore it should be magnetized.
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The CKP sensor should output a voltage near 1100-1300 mV as the crankshaft turns. It is possible to trigger the ICM with a voltage as low as 200 mV. If no voltage is produced, a poor CKP sensor electrical connection or malfunctioning CKP sensor is indicated.
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The test light connected to B+ simulates a reference signal to the PCM. An fuel injector test light can be installed and will blink for every other touch of the test light if the CKP Activity (7X reference) circuit, the PCM and the fuel injector driver are all functioning properly.
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Notice: Do not leave the jumper wire connected to the PCM IC circuit connector for longer than 5 seconds at a time. Failure to do so may damage the ignition coil and/or the Ignition Control Module.
This step checks the ignition control circuits and the ICM.
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The replacement PCM must be reprogrammed and the crankshaft position system variation procedure must be performed. Refer to the latest Techline procedures for PCM reprogramming and to the Crankshaft Position System Variation Learn for the Crankshaft Position System Variation Procedure .
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Battery voltage should be available at the fuel injector ignition feed circuit whenever the fuel pump power feed circuit is switched ON and when the PCM is receiving ignition pulses, during engine cranking or when the engine is running. The ignition switch must be turned OFF for at least 10 seconds to assure that the PCM powers down and will then switch the fuel pump back ON for 2-3 seconds when the ignition switch is turned back ON.
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The fuel pump is turned ON by the PCM for 2-3 seconds after the ignition switch is first turned ON. This step checks to see if the fuel pump and fuel pump relay are operating correctly and if the fuel pressure is within the proper range. Refer to the Fuel System Diagnosis .
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | |||
Are DTCs P0601, P0602, P1621, P1630, or P1632 set? | -- | Go to the applicable DTC tables | ||
Inspect the PCM ground connection at the engine block. Is the ground connection OK? | -- | |||
4 | Inspect the fuel pump and injector ignition feed fuse. Is the fuse OK? | -- | ||
5 | Repair PCM ground connection. Is the action complete? | -- | -- | |
6 | Check the fuel level and add fuel if necessary. Was it necessary to add fuel? | -- | ||
Is the action complete? | -- | -- | ||
Does the TP sensor read less than the specified value? | 1.0V | Go to DTC P0123 Throttle Position (TP) Sensor Circuit High Voltage | ||
Is the Engine Coolant Temperature (ECT) relatively close to the Intake Air Temperature (IAT)? | -- | Go to DTC P0117 Engine Coolant Temperature (ECT) Sensor Circuit Low Voltage or DTC P0118 Engine Coolant Temperature (ECT) Sensor Circuit High Voltage | ||
Does the MAP sensor read over the specified value and then change while cranking the engine? | 4.0V | |||
Crank the engine. Does the CKP Active Counter increment while cranking? | -- | |||
Was serial data lost while cranking the engine? | -- | |||
Repair voltage loss to the PCM from the ignition switch. Is the action complete? | -- | -- | ||
Is spark observed on all of the cables? | -- | |||
15 |
Is the resistance reading within the specified value? | 700-1300ohms | ||
Is the CKP sensor magnetic with undamaged terminals and the resistance with the specified value? | 700-1300ohms | |||
Is the voltage reading greater than the specified value? | 200 Mv | |||
Connect a test light to the cavity D of the ICM harness electrical connector and then take the other end of the test light and touch battery ground then touch B+. Does the CKP Activity Counter increment as the test light touches B+? | -- | |||
19 | Repair the open or a short in the CKP sensor electrical harness. Is the action complete? | -- | -- | |
20 | Replace the CKP sensor. Refer to Crankshaft Position Sensor Replacement Is the action complete? | -- | -- | |
21 |
Does test light illuminate? | -- | ||
22 | Connect a test light to ground and probe cavity B on the 2 pin ICM electrical connector. Does test light illuminate? | -- | ||
23 | Repair the malfunctioning ground circuit. Is the action complete? | -- | -- | |
24 | Check the CKP Activity (7X Reference) circuit for open or a short and repair as necessary. Was repair necessary? | -- | ||
25 | Repair the malfunctioning ICM ignition feed circuit. Is the action complete? | -- | -- | |
Notice: Do not leave the jumper wire connected to the PCM IC circuit connector for longer than 5 seconds at a time. Failure to do so may damage the ignition coil and/or the Ignition Control Module. Does a spark jump across the spark tester? | -- | |||
27 | Using a DMM, measure the resistance of the spark plug cable that the spark plug tester did not spark. Is the resistance of the spark plug cable less than the specified value? | 30000ohms | ||
28 | Using a DMM measure the secondary coil resistance. Is the secondary coil resistance within the specified value? | 5-8K ohms | ||
29 |
Was spark observed on the spark tester? | -- | ||
30 | Replace the ICM. Refer to Ignition Control Module Replacement . Is the action complete? | -- | -- | |
31 | Inspect the PCM electrical connector and connections. Are the connections OK? | -- | ||
32 | Check the affected cylinders ignition control circuit for an open or short and repair as necessary. Was a repair necessary? | -- | ||
33 | Repair the connector or connections. Is the action complete? | -- | -- | |
Replace the PCM. Refer to Powertrain Control Module Replacement . Is the action complete? | -- | -- | ||
35 | Replace the spark plug cable. Refer to Spark Plug Wire Harness Replacement in Engine Electrical. Is the action complete? | -- | -- | |
36 | Replace the malfunctioing ignition coil. Refer to Spark Plug Wire Harness Replacement in Engine Electrical. Is the action complete? | -- | -- | |
Does the test light blink on all cylinders? | -- | |||
Important: The ignition switch may have to be cycled more than one time to achieve the highest fuel pressure. Is the fuel pressure between the specified values? | 284-325 kPa (41-47 psi) | |||
39 | Check for fouled spark plugs and replace if necessary. Was spark plug replacement necessary? | -- | Go to Diagnostic Aids | |
40 | Repair the open in the fuel pump and injector ignition feed circuit. Is the action complete? | -- | -- | |
41 |
Does the engine start and continue to run? | -- | ||
42 |
Are any DTCs displayed? | -- | Go to Applicable DTC Table | System OK |
