Engine Cranks But Does Not Run. Pontiac Sunfire 1999

For 1990-2009 cars only

Makes 🢒 Pontiac 🢒 1999 🢒 Sunfire 🢒 Engine 🢒 Engine Controls - 2.4L 🢒 Engine Cranks But Does Not Run

Engine Controls Components
Ignition Controls
OBD II Symbol Description Notice
Powertrain Control Module Connector End Views
Handling ESD Sensitive Parts Notice

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 the following items:

•	Two separate ignition coils

•	Electronic Ignition Control Module (ICM)

•	Crankshaft Position (CKP) sensor

•	Related connecting wires and the ignition control portion of the PCM

Each secondary circuit consists of the following items:

•	Secondary winding of the coil

•	Two connecting metal strips that are molded into the coil housing

•	Spark plug boot/connector assemblies

•	Spark plugs

Diagnostic Aids

•	A small amount of resistance in the battery positive voltage circuit to the PCM may cause a no start with a functioning MIL. Check the battery positive voltage circuit for excessive resistance or corrosion.

•	Loss of Serial Data from the PCM to the IPC will cause no start condition.

•	Check the Throttle Position (TP) sensor for the following conditions:

Binding

Sticking

-	Intermittently shorted

-	Intermittently open

•	If the THEFT SYSTEM telltale is flashing on the Instrument Panel Cluster (IPC), the theft deterrent system has been activated, refer to the DTC P1629 Theft Deterrent Fuel Enable Signal Not Received 2.4L, or the DTC P1629 Theft Deterrent Fuel Enable Signal Not Received 2.2L for further diagnosis.

•	Check the fuel system for the following conditions:

-	Alcohol contaminants

Water

-	Foreign material

•	Check for a basic engine problem (low compression, timing chain ect.).

•	A scan tool can be used to energize the following items:

-	Fuel pump ON to check the fuel pump operation

-	Fuel injector to check for Ignition voltage at the fuel injector harness

Test Description

Number(s) below refer to the step number(s) on the Diagnostic Table.

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.

Diagnosis of the DTCs that may be set could lead to the cause of the Cranks But Will Not Run condition.

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.

Locate and repair any shorts that may have caused the fuse to open before replacing the fuse.

A TP sensor that reads too high may cause an incorrect fueling condition (Clear flood enabled).

An engine that has not been started or recently 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. If a malfunctioning coolant sensor is suspected, the spark plugs may have fouled out and need to be replaced to start the engine.

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.

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. If a malfunctioning MAP sensor is suspected, the spark plugs mat have fouled out and need to be replaced.

While cranking the engine, the CKP Activity (7X reference should increment to 255, then rollover to 0.

Check for possible voltage loss to the PCM including the ignition switch itself.

The ignition positive voltage should be available at the ignition feed terminal (L) of the ICM 11 pin harness electrical connector, and the ground terminal (K) should be a good ground.

The CKP sensor core is a magnet and should be magnetized.

The CKP sensor should output a AC 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 a malfunctioning CKP sensor is indicated.

The test light connected to B+ simulates a reference signal to the PCM. A 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 circuits are all functioning properly.

If the test light illuminates while probing the CKP Activity (7X reference) circuit, then the CKP Activity (7X reference) circuit is shorted to ground. If the test light remains OFF and the CKP Activity Counter does not increment, then the CKP Activity (7X reference) circuit is open. If the CKP Activity Counter increment several counts, when the reference low (terminal H) is probed, then the CKP Activity (7X reference) is shorted to voltage.

Replacement PCMs must be reprogrammed and the crankshaft position system variation learn procedure must be performed. Refer to the latest Techline information for PCM programming and the CKP System Variation Learn Procedure for the Crankshaft Position System Variation Procedure.

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 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.

By installing the spark plug jumper leads and testing for spark on all 4 plug wire leads (one at a time), each ignition coil(s) ability to produced at least 25,000 volts is verified.

The fuel pump is turned ON by the PCM for 2-3 seconds after 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 for fuel pressure gauge installation procedure.

This step verifies that the PCM is sending a signal to the Ignition Control Module (ICM) to fire the ignition coils. If the test light blinks, then the signal is OK to this point and the no spark condition lies in the ignition coil electrical harness or the ignition coil that did not produce spark.

The ignition coil electrical harness can easily be checked by performing the previous step with the ignition coil electrical harness connected to the ICM. Check for a voltage and ground signal to the ignition coils at the coil electrical connector.