Service Manual2008 Captiva DIAGNOSIS

Captiva

DIAGNOSIS

SYSTEM DIAGNOSIS

Diagnostic Aids

If an intermittent problem is evident, follow the guidelines below.

Preliminary Checks

Before using this section you should have already performed the "Diagnostic System Check."

Perform a thorough visual inspection. This inspection can often lead to correcting a problem without further checks and can save valuable time. Inspect for the following conditions:

Engine control module (ECM) grounds for being clean, tight, and in their proper location.
Vacuum hoses for splits, kinks, collapsing and proper connections as shown on the Vehicle Emission Control Information label. Inspect thoroughly for any type of leak or restriction.
Air leaks at the throttle body mounting area and the intake manifold sealing surfaces.
Ignition wires for cracks, hardness, proper routing, and carbon tracking.
Wiring for proper connections.
Wiring for pinches or cuts.

Diagnostic Trouble Code Tables

Do not use the Diagnostic Trouble Code (DTC) tables to try to correct an intermittent fault. The fault must be present to locate the problem.

Incorrect use of the DTC tables may result in the unnecessary replacement of parts.

Faulty Electrical Connections or Wiring

Most intermittent problems are caused by faulty electrical connections or wiring. Perform a careful inspection of suspect circuits for the following:

Poor mating of the connector halves.
Terminals not fully seated in the connector body.
Improperly formed or damaged terminals. All connector terminals in a problem circuit should be carefully inspected, reformed, or replaced to insure contact tension.
Poor terminal-to-wire connection. This requires removing the terminal from the connector body.

Road Test

If a visual inspection does not find the cause of the problem, the vehicle can be driven with a voltmeter or a scan tool connected to a suspected circuit. An abnormal voltage or scan tool reading will indicate that the problem is in that circuit.

If there are no wiring or connector problems found and a DTC was stored for a circuit having a sensor, replace the sensor.

Fuel System

Some intermittent driveability problems can be attributed to poor fuel quality. If a vehicle is occasionally running rough, stalling, or otherwise performing badly, ask the customer about the following fuel buying habits:

Do they always buy from the same source? If so, fuel quality problems can usually be discounted.
Do they buy their fuel from whichever fuel station that is advertising the lowest price? If so, check the fuel tank for signs of debris, water, or other contamination.

Idle Learn Procedure

The following idle learn procedure must be performed whenever one or more of the actions listed below are taken;

Replacement of new ECM

Replacement of new throttle body (MTIA, ETC)

Replacement of new IAC valve

Cleaning of carbon deposit on the throttle body

Power disconnection (battery cable, ECM fuse, etc.) (Delphi ECM only)

Turn the ignition ON.
Reset the adaptation values using the scan tool. (MTIA, ETC only)
Turn the ignition OFF for 15 seconds.
Turn the ignition ON for 5 seconds.
Turn the ignition OFF for 15 seconds. (For Siemens D160 ECM with ETC system, turn the ignition OFF for 35 seconds.)
Start the engine in park/neutral.
If the vehicle is equipped with an automatic transaxle, apply the parking brake. While pressing the brake pedal, place the transaxle in D (Drive) for 1 second and return to P (Park). (Siemens ECM only).
Allow the engine to run until the engine coolant is above 85°C (185°F).
Turn the A/C ON for 10 seconds, if equipped.
If the vehicle is equipped with an automatic transaxle, apply the parking brake. While pressing the brake pedal, place the transaxle in D (drive) for 10 seconds.
Turn the A/C OFF for 10 seconds, if equipped.
If the vehicle is equipped with an automatic transaxle, while pressing the brake pedal, place the transaxle in park/neutral.
Turn the ignition OFF. The idle learn procedure is complete.
Wait for 15 seconds before restarting the engine (Siemens ECM only). (For Siemens D160 ECM with ETC system, turn the ignition OFF for 35 seconds.)

Diagnostic System Check

Circuit Description

The Diagnostic system check is the starting point for any driveability complaint diagnosis. Before using this procedure, perform a careful visual/physical check of the engine control module (ECM) and the engine grounds for cleanliness and tightness.

The diagnostic system check is an organized approach to identifying a problem created by an electronic engine control system malfunction.

Diagnostic Aids

An intermittent may be caused by a poor connection, rubbed-through wire insulation or a wire broken inside the insulation. Check for poor connections or a damaged harness. Inspect the ECM harness and connections for improper mating, broken locks, improperly formed or damaged terminals, poor terminal-to-wire connection, and damaged harness.

Test Description

Numbers below refer to the step number on the Diagnostic Chart:

The Malfunction Indicator Lamp (MIL) should be ON steady with the ignition ON and the engine OFF. If not, go to "Diagnostic Aids".
Checks the Class 2 data circuit and ensures that the ECM is able to transmit serial data.
This test ensures that the ECM is capable of controlling the MIL and the MIL driver circuit is not shorted to ground.
If the engine will not start, refer to "Engine Cranks But Will Not Run" in this section.
A scan tool parameter which is not within the typical range may help to isolate the area which is causing the problem.
This vehicle is equipped with a ECM which utilizes an Electrically Erasable Programmable Read Only Memory (EEPROM). The replacement ECM must be programmed. Refer to the latest Techline procedure for ECM reprogramming.

Diagnostic System Check

Step	Action	Value(s)	Yes	No
1	Turn the ignition switch to ON. Observe the Malfunction Indicator Lamp (MIL). Is the MIL illuminate?	-	Go to Step 2	Go to "Malfunction Indicator Lamp (MIL) Inoperation"
2	Turn the ignition switch to LOCK. Install the scan tool to the Data link Connector (DLC). Turn the ignition switch to ON. Attempt to display the Engine Control Module (ECM) engine data with the scan tool. Does the scan tool display the ECM engine data?	-	Go to Step 3	Go to Step 8
3	Using the scan tool output test function, select the MIL lamp control and command the MIL off. Observe the MIL. Does the MIL turn OFF?	-	Go to Step 4	Go to "Malfunction Indicator Lamp (MIL) Always On"
4	Attempt to start the engine. Does the engine start and continue to run?	-	Go to Step 5	Go to "Engine Cranks But Will Not Run"
5	Select DISPLAY DTC with the scan tool. Are any Diagnostic Trouble Codes (DTCs) stored?	-	Go to Step 6	Go to Step 7
6	Check the display for DTCs P0107, P0108, P0113, P0118, P0122, P0123. Are two or more of the following DTCs stored?	-	Go to "Multiple ECM Information Sensor DTCs Set"	Go to applicable DTC table
7	Compare the ECM data values displayed on the scan tool to the typical engine scan data values. Are the displayed values normal or close to the typical values?	-	Go to "ECM Output Diagnosis"	Go to indicated component system check
8	Turn the ignition switch to LOCK. Disconnect the ECM connector. Turn the ignition switch to ON. Check the serial data circuit for an open, short to ground, or short to voltage. Also check the DLC ignition feed circuit for an open or short to ground, and check the DLC ground circuits for an open. Is a problem found?	-	Go to Step 9	Go to Step 10
9	Repair the open, short to ground, or short to voltage in the serial data circuit or the DLC ignition feed circuit. Is the repair complete?	-	System OK	-
10	Attempt to reprogram the ECM. Attempt to display the ECM data with the scan tool. Does the scan tool display ECM engine data?	-	Go to Step 2	Go to Step 11
11	Replace the ECM. Is the replacement complete?	-	System OK	-

ECM Output Diagnosis

Circuit Description

The Engine Control Module (ECM) controls most components with electronic switches which complete a ground circuit when turned on. These switches are arranged in groups of 4 and 7, and they are called either a Surface Mounted Quad Driver Module, which can independently control up to 4 output terminals or an Output Driver Module (ODM), which can independently control up to 7 outputs. Not all of the outputs are always used.

Drivers are fault protected. If a relay or solenoid is shorted, having very low or zero resistance, or if the control side of the circuit is shorted to voltage, it would allow too much current flow into the ECM. The driver senses this and the output is either turned OFF or its internal resistance increases to limit current flow and protect the ECM and driver. The result is high output terminal voltage when it should be low. If the circuit from B+ to the component or the component is open, or the control side of the circuit is shorted to ground, terminal voltage will be low. Either of these conditions is considered to be a driver fault.

Drivers also have a fault line to indicate the presence of a current fault to the ECM's central processor. A scan tool displays the status of the driver fault lines as 0=OK and 1=Fault.

Diagnostic Aids

The scan tool has the ability to command certain components and functions ON and OFF. If a component or function does not have this capability, operate the vehicle during its normal function criteria to check for an open or shorted circuit.

An open or short to ground will appear in the open positions on the scan tool only when it is not commanded by the ECM or the scan tool, while a short to voltage will appear in the short positions on the scan tool only while the component is being commanded by the ECM or scan tool.

ECM Output Diagnosis

Step	Action	Value(s)	Yes	No
1	Perform the Diagnostic system check. Is the check complete.	-	Go to Step 2	Go to "Malfunction Indicator Lamp (MIL) Inoperation"
2	Install the scan tool. Is there a number to the Data Link Connector (DLC) 1 (=fault) below any of the numbered positions in the OUTPUT DRIVERS?	-	Go to Step 3	Go to Step 4
3	Check for an open or shorted circuit in any corresponding position (circuit) that contained a number 1 and repair as needed. Is the repair complete?	-	Go to Step 9	Go to Step 7
4	Command the output being checked with a scan tool while watching the corresponding position for each circuit. Do any of the position changed to a 1?	-	Go to Step 6	Go to Step 5
5	Command the output being checked with a scan tool while watching the corresponding position for each circuit. Does the component or function operate when commanded?	-	Go to Step 9	Go to the appropriate component table for repair
6	Repair the short to voltage in the corresponding circuit for position (circuit) that displayed at a 1. Is the repair complete?	-	Go to Step 9	-
7	Disconnect the electrical connector to the component connected to the fault circuit. Is a 1 still displayed in the corresponding OUTPUT DRIVER position?	-	Go to Step 8	Go to the appropriate component table for repair
8	Replace the Engine control Module (ECM). Is the replacement complete?	-	Go to Step 9	-
9	Operate the vehicle within the conditions under which the original symptom was noted. Does the system now operate properly?	-	System OK	Go to Step 2

Multiple ECM Information Sensor DTCs Set

Circuit Description

The Engine Control Module (ECM) monitors various sensors to determine engine operating conditions. The ECM controls fuel delivery, spark advance, transaxle operation, and emission control device operation based on the sensor inputs.

The ECM provides a sensor ground to all of the sensors. The ECM applies 5 volts through a pull-up resistor and monitors the voltage present between the sensor and the resistor to determine the status of the Engine Coolant Temperature (ECT) sensor, the Intake Air Temperature (IAT) sensor. The ECM provides the Exhaust Gas Recirculation (EGR) Pintle Position Sensor, the Throttle Position (TP) sensor, the Manifold Absolute Pressure (MAP) sensor with a 5 volt reference and a sensor ground signal. The ECM monitors the separate feedback signals from these sensors to determine their operating status.

Diagnostic Aids

Be sure to inspect the ECM and the engine grounds for being secure and clean.

A short to voltage in one of the sensor circuits can cause one or more of the high voltage/input DTCs to be set.

If a sensor input circuit has been shorted to voltage, ensure that the sensor is not damaged. A damaged sensor will continue to indicate a high or low voltage after the affected circuit has been repaired. If the sensor has been damaged, replace it.

An open in one of the sensor circuits will cause one or more of the high or low voltage/input DTCs to be set.

A short to ground in one of the sensor circuits will cause one or more of the low voltage/input DTCs to be set.

Check for the following conditions:

Inspect for a poor connection at the ECM. Inspect harness connectors for backed-out terminals, improper mating, broken locks, improperly formed or damaged terminals, and poor terminal-to-wire connection.
Inspect the wiring harness for damage. If the harness appears to be OK, observe an affected sensor's displayed value on the scan tool with the ignition ON and the engine OFF while moving connectors and wiring harnesses related to the affected sensors. A change in the affected sensor's displayed value will indicate the location of the fault.

Multiple ECM Information Sensor DTCs Set

Step	Action	Value(s)	Yes	No
1	Perform the Diagnostic System Check. Is the check complete.	-	Go to Step 2	Go to "Diagnostic System Check"
2	Turn the ignition OFF and disconnect the Engine Control Module (ECM). Turn the ignition ON and check the 5 volt reference circuit for the following conditions: Poor connection at the ECM. Open between the ECM connector affected sensors shorted to ground or voltage. If a problem is found, locate and repair the open or short circuit as needed. Is a problem found?	-	Go to Step 17	Go to Step 3
3	Check the sensor ground circuit for the following conditions: Poor connection at the ECM or affected sensors. Open between the ECM connector and the affected sensors. If a problem is found, repair it as needed. Is a problem found?	-	Go to Step 17	Go to Step 4
4	Measure the voltage of the Exhaust Gas Recirculation (EGR) Pintle Position Sensor signal circuit between ECM harness connector and ground. Does the voltage measure near the specified value?	0 V	Go to Step 5	Go to Step 9
5	Measure the voltage of the Manifold Absolute Pressure (MAP) sensor signal circuit between the ECM harness connector and ground. Does the voltage measure near the specified value?	0 V	Go to Step 6	Go to Step 11
6	Measure the voltage of the Throttle Position (TP) sensor signal circuit between the ECM harness connector and ground. Does the voltage measure near the specified value?	0 V	Go to Step 7	Go to Step 12
7	Measure the voltage of the Intake Air Temperature (IAT) sensor signal circuit between the ECM harness connector and ground. Does the voltage measure near the specified value?	0 V	Go to Step 8	Go to Step 13
8	Measure the voltage of the Engine Coolant Temperature (ECT) sensor signal circuit between the ECM harness connector and ground. Does the voltage measure near the specified value?	0 V	Go to Step 16	Go to Step 14
9	Disconnect the EGR valve. Measure the voltage of the EGR Pintle Position sensor signal circuit between the ECM harness connector and ground. Does the voltage measure near the specified value?	0 V	Go to Step 10	Go to Step 15
10	Replace the EGR valve. Is the repair complete?	-	Go to Step 17	-
11	Locate and repair the short to voltage in the MAP sensor signal circuit. Is the repair complete?	-	Go to Step 17	-
12	Locate and repair the short to voltage in the TP sensor signal circuit. Is the repair complete?	-	Go to Step 17	-
13	Locate and repair the short to voltage in the IAT sensor signal circuit. Is the repair complete?	-	Go to Step 17	-
14	Locate and repair the short to voltage in the ECT sensor signal circuit. Is the repair complete?	-	Go to Step 17	-
15	Locate and repair the short to voltage in the EGR Pintle Position sensor circuit. Is the repair complete?	-	Go to Step 17	-
16	Replace the ECM. Is the repair complete?	-	Go to Step 17	-
17	Using the scan tool, clear the Diagnostic Trouble Codes (DTCs). Start the engine and idle at normal operating temperature. Operate the vehicle within the conditions for setting the DTCs as specified in the supporting text. Does the scan tool indicate that this diagnostic ran and passed?	-	Go to Step 18	Go to Step 2
18	Check if any additional DTCs are set. Are any DTCs displayed that have not been diagnosed?	-	Go to "Applicable DTC table"	System OK

Engine Cranks But Will Not Run

Test Description

The number(s) below refer to step(s) on the diagnostic table.

The Diagnostic 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 occurred. The information is then stored on the scan tool for later reference.
The Diagnostic 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 occurred. The information is then stored on the scan tool for later reference.
By performing a compression test, it can be determined if the engine has the mechanical ability to run.
By performing a compression test, it can be determined if the engine has the mechanical ability to run.
It is important to check for the presence of spark from all of the ignition wires. If spark is present from one to three of the ignition coil terminals, the Crankshaft Position (CKP) sensor is OK.
It is important to check for the presence of spark from all of the ignition wires. If spark is present from one to three of the ignition coil terminals, the Crankshaft Position (CKP) sensor is OK.

In checking the engine control module (ECM) outputs for the electronic spark timing signal, it recommended to use an oscilloscope to view the varying voltage signals. In measuring these outputs with a voltmeter, intermittent errors may occur that cannot be seen by a voltmeter.
This step checks for proper operation of the ECM's control of the fuel pump circuit.
This step checks for a ground signal being supplied by the ECM to operate the fuel injectors. If there is no ground present during the cranking of the engine, and the fuel injector wiring is OK, the ECM is at fault.

Engine Cranks But Will Not Run

Caution : Use only electrically insulated pliers when handling ignition wires with the engine running to prevent an electrical shock.

Caution : Do not pinch or restrict nylon fuel lines. Damage to the lines could cause a fuel leak, resulting in possible fire or personal injury.

Step	Action	Value(s)	Yes	No
1	Perform the Diagnostic System Check. Was the check performed?	-	Go to Step 2	Go to "Diagnostic System Check"
2	Check for set Diagnostic Trouble Code (DTC) P0601. Is the DTC set?	-	Go to applicable DTC table	Go to Step 4
3	Crank the engine. Does the engine start and continue to run?	-	System OK	Go to Step 5
4	Perform a cylinder compression test. Is the cylinder compression for all of the cylinders at or above the value specified?	689 kPa (100 psi)	Go to Step 8	Go to Step 5
5	Inspect the timing belt alignment. Is the timing belt in alignment?	-	Go to Step 7	Go to Step 6
6	Align or replace the timing belt as needed. Is the repair complete?	-	Go to Step 3	-
7	Repair the internal engine damage as needed. Is the repair complete?	-	Go to Step 3	-
8	Inspect the fuel pump fuse. Is the problem found?	-	Go to Step 9	Go to Step 10
9	Replace the fuse. Is the repair complete?	-	Go to Step 3	-
10	Install a scan tool. Turn the ignition ON, the engine OFF and close the throttle. Does the Throttle Position (TP) sensor read less than the specified value.	1.0 v	Go to Step 11	Go to "DTC P0123 Throttle Position Sensor High Voltage"
11	Compare the Engine Coolant Temperature (ECT) with the Intake Air Temperature (IAT). Is the ECT relatively close to the IAT?	-	Go to Step 12	Go to "DTC P0118 Engine Coolant Temperature High Voltage
12	Check if the Manifold Absolute Pressure (MAP) sensor reading is over the specified reading. Crank the engine while watching the MAP sensor reading. Does the MAP sensor read above the specified value and then change while cranking the engine?	4 v	Go to Step 13	Go to Step 14
13	Crank the engine. Does the Crankshaft Position (CKP) Active Counter increment while cranking?	-	Go to Step 16	Go to Step 18
14	Check the scan data for serial data. Was serial data lost while cranking the engine?	-	Go to Step 15	Go to "MAP Sensor Output Check"
15	Repair voltage loss to the engine control module (ECM) from the ignition switch. Is the repair complete?	-	System OK	-
16	Check for the presence of spark from all of the ignition wires while cranking the engine. Is spark present from all of the ignition wires?	-	Go to Step 41	Go to Step 17
17	Measure the resistance of the ignition wires. Replace any of the ignition wire(s) with a resistance above the value specified. Check for the presence of spark from all of the ignition wires. Is spark present from all of the ignition wires?	30,000 W	Go to Step 3	Go to Step 18
18	Turn the ignition OFF. Disconnect the Crankshaft Position (CKP) sensor connector. Measure the voltage between the CKP connector terminals 1 and 3. Repair the wiring as needed. Does the voltage measure near the value specified?	1.4 v (2.5 v)*	Go to Step 19	Go to Step 20
19	Measure the voltage between the CKP connector terminals 2 and 3. Does the voltage measure near the value specified	1.4 v (2.5 v)*	Go to Step 26	Go to Step 21
20	Measure the voltage between the CKP connector terminals 1 and ground. Does the voltage measure near the value specified?	1.4 v (2.5 v)*	Go to Step 22	Go to Step 23
21	Measure the voltage between the CKP connector terminals 2 and ground. Does the voltage measure near the value specified?	1.4 v (2.5 v)*	Go to Step 22	Go to Step 24
22	Check for an open or short in the wire between the CKP connector terminal 3 and ground. Is the problem found?	-	Go to Step 25	Go to Step 40
23	Check for an open or short in the wire between the CKP connector terminal 1 and the ECM connector J2 terminal 14. Is the problem found?	-	Go to Step 25	Go to Step 40
24	Check for an open or short in the wire between the CKP connector terminal 2 and the ECM connector J2 terminal 15. Is the problem found?	-	Go to Step 25	Go to 40
25	Repair the wiring as needed. Is the repair complete?	-	Go to Step 3	-
26	Disconnect the Electronic Ignition (EI) system ignition coil connector to prevent the vehicle from starting. Measure the voltage at the ECM connector J2 terminal 14 by backprobing the ECM connector. Are the voltage readings near the values specified?	1.4 v (2.5 v)* with ignition ON, 1.6 v (2.6 v)* during cranking	Go to Step 27	Go to Step 28
27	Measure the voltage at the ECM connector J2 terminal 15 by backprobing the ECM connector. Are the voltage readings near the values specified?	1.4 v (2.5 v)* with ignition ON, 1.6 v (2.6 v)* during cranking	Go to Step 29	Go to Step 28
28	Replace the CKP sensor. Is the repair complete?	-	Go to Step 3	-
29	Turn the ignition OFF. Disconnect the electrical connector at the EI system ignition coil. Connect a test light between terminal 2 of the EI system ignition coil connector and ground. Turn the ignition ON. Is the test light on?	-	Go to Step 30	Go to Step 31
30	Connect a test light of the EI system ignition coil connector and battery positive. Is the test light on?	-	Go to Step 34	Go to Step 32
31	Check for an open in the wiring between the ignition switch and the EI system ignition coil connector terminal 1. Is the problem found?	-	Go to Step 33	-
32	Check for an open in the wire from the EI system ignition coil to ground. Is the problem found?	-	Go to Step 2	-
33	Repair the wiring as needed. Connect the EI system ignition coil connector. Check for the presence of spark from all of the ignition wires. Is spark present from all of the ignition wires?	-	Go to Step 3	Go to Step 34
34	Turn the ignition OFF. Disconnect the EI system ignition coil connector. While cranking the engine, measure the voltage at the EI system ignition coil connector terminal 3. Does the voltage fluctuate within the values specified?	0.2-2.0 v	Go to Step 39	Go to Step 37
35	While cranking the engine, measure the voltage at the EI system ignition coil connector terminal 1. Does the voltage fluctuate within the values specified?	0.2-2.0 v	Go to Step 39	Go to Step 37
36	Check for an open in the wire from the EI system ignition coil connector terminal 3 to the ECM connector J2 terminal 35. Is the problem found?	-	Go to Step 38	Go to Step 40
37	Check for an open in the wire from the EI system ignition coil connector terminal 1 to the ECM connector J2 terminal 40. Is the problem found?	-	Go to Step 38	Go to Step 40
38	Repair the wiring as needed. Connect the EI system ignition coil connector. Check for the presence of spark from all of the ignition wires. Is spark present from all of the ignition wires?	-	Go to Step 3	Go to Step 39
39	Replace the EI system ignition coil. Is the repair complete?	-	Go to Step 3	-
40	Turn the ignition OFF. Replace the ECM. Is the repair complete?	-	Go to Step 3	-
41	Turn the ignition OFF. Connect a fuel pressure gauge. Crank the engine. Is any fuel pressure present?	-	Go to Step 44	Go to Step 42
42	Turn the ignition OFF. Disconnect the electrical connector at the fuel pump. Connect a test light between the fuel pump connector terminals 4 and 5. Turn the ignition ON. With the ignition ON, the test light should light for the time specified. Is the test light on?	2 sec	Go to Step 43	Go to Step 53
43	Replace the fuel pump. Is the repair complete?	-	Go to Step 3	-
44	Is the fuel pressure within the value specified?	283-324 kPa (41-47 psi)	Go to Step 48	Go to Step 45
45	Check the fuel filter for a restriction. Inspect the fuel lines for kinks and restrictions. Is the problem found?	-	Go to Step 46	Go to Step 47
46	Disconnect the vacuum line from the fuel pressure regulator. Inspect the vacuum line for the presence of fuel. Inspect the fuel pressure regulator vacuum port for the presence of fuel. Is any fuel present?	283-324 kPa (41-47 psi)	Go to Step 3	Go to Step 47
47	Disconnect the vacuum line from the fuel pressure regulator. Inspect the vacuum line for the presence of fuel. Inspect the fuel pressure regulator vacuum port for the presence of fuel. Is any fuel present.	-	Go to Step 50	Go to Step 51
48	Check the fuel for contamination. Is the fuel contaminated?	-	Go to Step 49	Go to Step 65
49	Remove the contaminated fuel from the fuel tank. Clean the fuel tank as needed. Is the repair complete?	-	Go to Step 3	-
50	Replace the fuel pressure regulator. Is the repair complete?	-	Go to Step 3	-
51	Remove the fuel pump assembly from the fuel tank. Inspect the fuel pump sender and the fuel coupling hoses for a restriction. Inspect the in-tank fuel filter for a restriction. Is the problem found?	-	Go to Step 52	Go to Step 43
52	Replace the fuel pump sender, the in-tank fuel filter, and/or the fuel coupling hoses as needed. Is the repair complete?	-	Go to Step 3	-
53	Turn the ignition OFF. Disconnect the electrical connector at the fuel pump. Connect a test light between the fuel pump connector terminal 4 and a known good ground. Turn the ignition ON. With the ignition ON, the test light should light for the time specified. Is the test light on?	2 sec	Go to Step 54	Go to Step 55
54	Repair the open wire between the fuel pump connector terminal 5 and ground. Is the repair complete	-	Go to Step 3	-
55	Turn the ignition OFF. Disconnect the fuel pump relay. Connect a test light between the fuel pump relay connector terminal 85 and ground. Turn the ignition ON. Is the test light on?	2 sec	Go to Step 56	Go to Step 62
56	Turn the ignition OFF. Connect a test light between the fuel pump relay connector terminal 86 and battery positive. Turn the ignition ON. With the ignition ON, the test light should light for the time specified. Is the test light on?	-	Go to Step 57	Go to Step 61
57	Turn the ignition OFF. Connect a test light between the fuel pump relay connector terminal 30 and ground. Is the test light on?	-	Go to Step 58	Go to Step 64
58	Turn the ignition OFF. Check the wire between the fuel pump relay connector terminal 87 and the fuel pump connector terminal 3 for an open or short to ground. Is the repair complete?	-	Go to Step 2	-
59	Replace the fuel cutoff switch. Is the problem found?	-	Go to Step 3	-
60	Replace the fuel pump relay. Is the repair complete?	-	Go to Step 3	-
61	Check for an open in the wiring between the fuel pump relay connector terminal 86 and ground. Is the problem found?	-	Go to Step 72	-
62	Check the wire between the fuel pump relay connector terminal 85 to the ECM connector J1 terminal 51 for an open. Is the problem found?	-	Go to Step 63	Go to Step 40
63	Repair the wire between the fuel pump relay connector terminal 85 to the ECM connector J1 terminal 51. Is the repair complete?	-	Go to Step 3	-
64	Repair the wire between the fuel pump relay connector terminal 30 and the positive battery. Is the repair complete?	-	Go to Step 3	-
65	Turn the ignition OFF. Disconnect the fuel injector harness connectors from all of the fuel injectors. Turn the ignition ON. Connect a test light between the fuel injector harness connector 1 and ground. Repeat step 4 for each of the remaining fuel injectors. Is the test light on at all of the fuel injectors?	-	Go to Step 66	Go to Step 69
66	Turn the ignition OFF. Connect a test light between the fuel injector harness connector terminal 2 and battery positive. Crank the engine. Repeat steps two and three for each of the remaining fuel injectors. Does the test light flash for all of the fuel injectors?	-	Go to Step 67	Go to Step 70
67	Measure the resistance of each fuel injector. Is the resistance within the value specified (the resistance will increase slightly at higher temperatures)?	11.6-12.4 Ω	System OK	Go to Step 68
68	Replace any of the fuel injectors with a resistance out of specification. Is the repair complete?	-	Go to Step 3	-
69	Repair the open wire(s) between the fuel injector harness connector(s) terminal 1 and the engine harness. Is the repair complete?	-	Go to Step 3	-
70	Check for an open between the #1 fuel injector harness connector terminal 2 and the ECM connector J2 terminal 26. Check for an open between the #2 fuel injector harness connector terminal 2 and the ECM connector J2 terminal 18. Check for an open between the #3 fuel injector harness connector terminal 2 and the ECM connector J2 terminal 10. Check for an open between the #4 fuel injector harness connector terminal 2 and the ECM connector J2 terminal 2. Is the problem found?	-	Go to Step 71	Go to Step 73
71	Repair the open fuel injector harness wire(s). Is the repair complete?	-	Go to Step 3	-
72	Replace the fuse or repair the wiring as needed. Is the repair complete?	-	Go to Step 3	-
73	Check for an open between the circuits from terminal 1 for each of the four fuel injectors and the ignition switch. Is the problem found?	-	Go to Step 72	-

Malfunction Indicator Lamp (MIL) Inoperation

Circuit Description

There should always be a steady malfunction indicator lamp (MIL) when the ignition switch is in the ON position and the engine is not running. System voltage is applied to the indicator bulb and the instrument panel cluster (IPC) provides a path to ground. Once the engine starts, the IPC turns OFF the MIL. When an engine control system malfunction occurs, the engine control module (ECM) sends a message over the high speed GMLAN to the body control module (BCM) requesting the MIL. The BCM then sends a message to the IPC over the low speed GMLAN requesting MIL illumination.

Test Description

The number below refers to the step number on the diagnostic table.

If other IPC functions are not working correctly, check for an open fuse or for a lack of power and ground to the IPC.

Malfunction Indicator Lamp (MIL) Inoperation

Step	Action	Value(s)	Yes	No
1	Attempt to start the engine. Does the engine start?	-	Go to Step 2	Go to "Diagnostic System Check"
2	Observe the instrument panel cluster (IPC) assembly operation. Do all other functions of the IPC function normally?	-	Go to Step 3	Go to Section 9E, Instrumentation/Driver Information
3	Replace the IPC. Did you complete the replacement?	-	Go to Step 4	-
4	Operate the system in order to verify the repair. Did you correct the condition?	-	System OK	Go to Step 2

Malfunction Indicator Lamp (MIL) Always On

Circuit Description

Diagnostic Aids

If the MIL is ON at all times, and there are no powertrain DTCs set, there is a condition with the serial data circuits.

Malfunction Indicator Lamp (MIL) Always On

Step	Action	Value(s)	Yes	No
1	Did you perform the Diagnostic System Check? Is the check complete.	-	Go to Section 9E, Instrumentation/Driver Information	Go to "Diagnostic System Check"