Engine Cranks But Does Not Run LD9
Refer to
Fuel Controls
and
Ignition Controls
for
wiring view.
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 may cause a no start with a functioning MIL. Check circuit C2-03 for resistance. |
| • | Check the Throttle Position (TP) sensor for binding or sticking or for being intermittently shorted or open. |
| • | If the THEFT SYSTEM telltale is flashing on the Instrument Panel Cluster (IPC), the theft deterrent system has been activated, refer to DTC P1629 Theft Deterrent Fuel Enable Signal Not Received for further diagnosis. |
| • | Check for water or foreign material in the fuel system. |
| • | Check for a basic engine problem (low compression). |
| • | Verify that only resistor spark plugs are used. |
| • | A scan tool can be used to energize the fuel pump ON to check fuel pump operation and for ignition voltage at the 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 fault occurred. The information is then stored in the scan tool for later reference.
-
Diagnosis of DTC's that may be set could lead to the cause of the Cranks But Will Not Run condition.
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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 replacement.
-
A TP sensor that reads too high may cause an incorrect fueling condition.
-
An engine that has not been started should display ECT and IAT temperatures that are relatively close to each other. During 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.
-
If the scan tool loses serial data only while cranking, the ignition switch is not sending voltage to the PCM while in the crank position.
-
Check for possible voltage loss to the PCM including the ignition switch itself.
-
Battery voltage should be available at the ignition feed terminal (L) of the ICM 11 pin harness connector, and the ground terminal (K) should be a good ground.
-
The CKP sensor core is a magnet, therefore it should be magnetized.
-
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 sensor connection or faulty sensor is indicated.
-
The test light connected to B+ simulates a reference signal to the PCM. An 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 injector driver are all functioning properly.
-
If the test light illuminates while probing the CKP Activity (7X reference) circuit, the CKP Activity (7X reference) circuit is shorted to ground. If the test light remains OFF and the CKP Activity Counter does not increment, the CKP Activity (7X reference) circuit is open. If the CKP Activity Counter increment several counts, when the reference low (cavity H) is probed, the CKP Activity (7X reference) is shorted to voltage.
-
Replacement PCM's must be reprogrammed. Refer to the latest Techline information for programming procedures.
-
Battery voltage should be available at the 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 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 is turned back ON.
-
By installing the spark plug jumper leads and testing for spark on all 4 plug wire leads, 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 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 Fuel System Diagnosis for fuel pressure gage installation procedure.
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Ignition voltage is supplied to the injectors and fuel pump for the first two seconds when the ignition is turned ONand continuouslywhen the engine is cranked. If the fuel pump runs but the injector test light did not blink, then the injector ignition feed circuit is open between the injector and the splice from the ignition feed circuit.
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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 harness or the ignition coil that did not produce spark.
-
The ignition coil harness can easily be checked by performing the previous step with the ignition coil harness connected to the ICM. Check for a voltage and ground signal to the ignition coils at the coil electrical connector.
-
This step checks the ignition control circuits and the PCM.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | |||
Are DTC(s) P0335, P0600, P0601, P0602, or P1629 set? | -- | Go to applicable DTC table | ||
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 the 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 then the specified value? | 1.0 V | |||
Is the Engine Coolant Temperature (ECT) relatively close to the Intake Air Temperature (IAT)? | -- | Go to L 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 V | |||
Crank the engine. Does the CKP Activity 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? | -- | -- | ||
Does the DVM read the specified voltage? | B+ | |||
15 |
Is the resistance reading within the specified value? | 500-900ohms | ||
16 | Repair the open in the ground or the ignition feed circuit to the ICM. Is the action complete? | -- | -- | |
Is the CKP sensor magnetic with undamaged terminals and the resistance within the specified value? | 500-900ohms | |||
Is the voltage reading greater than the specified value? | 200 mV | |||
With a test light connected to B+, touch the G cavity of the ICM harness connector and then the H cavity. Does the CKP Activity Counter increment one count as the test light touches cavity H? | -- | |||
20 | Repair the open or the short in the CKP sensor harness. Is the action complete? | -- | -- | |
21 | Replace the CKP sensor. Is the action complete? | -- | -- | |
22 | Visually inspect the ICM harness connector to see if the connections are clean and tight and repair if necessary. Was a repair necessary? | -- | ||
Check the CKP activity (7X reference) circuit for an open or short and repair as necessary. Was a repair necessary? | -- | |||
24 | Replace the ICM. Is the action complete? | -- | -- | |
Replace the PCM. Is the action complete? | -- | -- | ||
Does the test light blink? | -- | |||
Does spark jump the spark tester on all 4 spark plug wires? | -- | |||
Install a fuel pressure gage and note the pressure after the ignition switch is turned ON for 2 seconds. Is the fuel pressure between the specified value? | 284-325 kPa (41-47 psi) | |||
29 | Check for fouled spark plugs and replace if necessary. Was any spark plug replacement necessary? | -- | Go to Diagnostic Aids | |
Repair the open in the fuel pump and injector ignition feed circuit. Is the action complete? | -- | -- | ||
Does the test light blink while cranking the engine? | -- | |||
Check for a faulty ignition coil harness connection or open ignition coil harness and repair as necessary. Was a repair necessary? | -- | |||
Are the resistance readings within the specified value? | 0.06 K-2.6 K ohms | |||
34 | Replace the ignition coil that did not spark. Is the action complete? | -- | -- | |
35 | Check the ignition control circuit for an open or a short and repair as necessary. Was a repair necessary? | -- | ||
36 |
Does the engine start and continue to run? | -- | ||
37 |
Are any DTC's displayed that have not been diagnosed? | -- | Go to Applicable DTC table | System OK Refer to Diagnostic Aids |
Engine Cranks But Does Not Run Fuel Pump Circuit
Circuit Description
When the ignition switch is turned ON, the Powertrain Control Module (PCM) turns ON the in-tank fuel pump. It will remain ON as long as the PCM is receiving ignition reference pulses from the electronic Ignition Control Module (ICM). If there are no reference pulses, the PCM will shut OFF the fuel pump about 2-3 seconds after the ignition is turned ON, about 10 seconds after the reference pulses stop.
The fuel pump delivers fuel to the fuel rail and fuel injectors, then to the fuel pressure regulator, where the system pressure is controlled to 283-324 kPa (41-47 psi) with no manifold vacuum or 214-303 kPa (31-44 psi) at idle. Excess fuel is then returned to the fuel tank.
Improper fuel system pressure will result in one or all of the following symptoms:
| • | Cranks but will not run |
| • | DTC P0108 |
| • | DTC P0171 |
| • | DTC P0172 |
| • | DTC P0300 |
| • | DTC P1171 |
| • | Cuts out, may feel like an ignition problem |
| • | Poor fuel economy, loss of power |
| • | Hesitation |
Diagnostic Aids
An intermittent may be caused by a poor connections, rubbed through wire insulation, or a broken wire inside of the inslation.
Any circuitry, that is suspected as causing an intermittent complaint, should be throughly checked for the following conditions:
| • | Backed out terminals |
| • | Improper mating |
| • | Broken locks |
| • | Improperly formed or damaged terminals |
| • | Physical damage to the wiring harness |
| • | Corrosion |
Test Description
Number(s) below refer to step number(s) on the Diagnostic Table.
-
The Powertrain OBD System Check prompts the technician to complete some basic checks and stores the freeze frame and failure records 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.
-
If the no start condition was due to a open fuse, locate and repair any shorts that may have caused the fuse to open before replacement.
-
This step determines if the fuel pump circuit can be controlled by the PCM. The PCM should energize the fuel pump relay and turn the fuel pump ON when commanded by the scan tool. If the engine is not cranking or running, the PCM should de-energize the relay and turn OFF the fuel pump after 2-3 seconds.
-
Jumpering CKT 120 to CKT 839 verifies that the fuel pump relay ignition feed circuit, the fuel pump feed circuit, the fuel pump and fuel ground are all OK.
-
Check for an open CKT 451.
-
Replacement PCM's must be reprogrammed. Refer to the latest Techline information for programming procedures.
-
This step checks CKT 150 on the body side of the body harness only. If CKT 150 is OK, then CKT's 120 or 150 in the fuel tank harness or the fuel pump itself are at fault.
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This test will determine if a short to ground on CKT 120 caused the fuse to open. To prevent mis-diagnosis, be sure the fuel pump harness is disconnected before the test.
-
The fuel pump control circuit includes an engine oil pressure switch with a separate set of normally open contacts. The switch closes at about 28 kPa (4 psi) of oil pressure and provides a second battery feed path to the fuel pump. If the fuel pump relay is inoperative, the fuel pump will continue to run using the battery feed supplied by the closed oil pressure switch.
-
The only possible place CKT 120 can be open is between the oil pressure switch and the fuel pump relay, injector and the fuel pump splice.
-
The only possible place CKT 839 can be open is between the oil pressure switch and the fuel pump relay.
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
Was the Powertrain On-Board Diagnostic (OBD) System Check performed? | -- | |||
Inspect the fuel pump relay fuse. Is the fuse OK? | -- | |||
Does the in-tank fuel pump run when commanded ON? | -- | Go to Fuel System Diagnosis | ||
Does the fuel pump run? | -- | |||
5 |
Does the test light illuminate? | -- | ||
6 | With a test light connected to ground, probe the ignition feed terminal to the fuel pump relay. Is the test light ON? | -- | ||
With a test light connected to B+, probe the ground terminal to the fuel pump relay. Is the test light ON? | -- | |||
8 | Check for an open or short to ground in the fuel pump control circuit and repair as necessary. Was a repair necessary? | -- | ||
9 |
Does the test light illuminate? | -- | ||
10 | Repair the open in the ignition feed circuit for the fuel pump relay. Is the action complete? | -- | -- | |
11 | Replace the fuel pump relay. Is the action complete? | -- | -- | |
12 | Repair the open ground circuit to the fuel pump relay. Is the action complete? | -- | -- | |
13 | Inspect connections and terminals at the PCM and repair as necessary. Was a repair necessary? | -- | ||
14 | With a test light connected to B+, probe the fuel pump ground circuit (body side). Does the test light illuminate? | -- | ||
15 | Repair the open fuel pump feed circuit. Is the action complete? | -- | -- | |
Replace the PCM. Is the action complete? | -- | -- | ||
Check the fuel pump feed and ground circuits in the fuel pump harness for an open and repair as necessary. Was a repair necessary? | -- | |||
18 | Repair the open fuel pump ground circuit. Is the action complete? | -- | -- | |
19 | Replace the fuel pump. Is the action complete? | -- | -- | |
Does the test light illuminate? | -- | |||
21 | Repair the short to ground in the fuel pump feed circuit. Is the action complete? | -- | -- | |
22 | With the test light still connected to B+, probe the fuel pump relay ignition feed circuit terminal. Does the test light illuminate? | -- | ||
23 | Repair the short to ground in the fuel pump relay ignition feed circuit. Is the action complete? | -- | -- | |
24 | Check the fuel pump feed circuit in the fuel pump harness for a short to ground and repair as necessary. Was a repair necessary? | -- | ||
An additional check of the fuel pump and engine oil pressure switch and circuitry can be made at this point. Check the fuel pump and engine oil pressure switch and circuitry? | -- | |||
26 |
Does the engine continue to run? | -- | ||
27 |
Is the test light ON? | -- | ||
28 |
Is the test light ON? | -- | ||
29 | Replace the fuel pump and engine oil pressure switch. Is the action complete? | -- | -- | |
Repair the open fuel pump feed circuit from the fuel pump and the engine oil pressure switch. Is the action complete? | -- | -- | ||
Repair the open in the ignition feed circuit to the fuel pump and engine oil pressure switch. Is the action complete? | -- | -- | ||
32 |
Does the engine start and continue to run? | -- | ||
33 |
Are any DTC's displayed that have not been diagnosed? | -- | Go to applicable DTC table | System OK |
