Engine Controls - 4.6l (lh2) - Troubleshooting

Important Preliminary Inspections Before Starting

Before using this section, perform the Diagnostic System Check - Vehicle in Vehicle DTC Information and verify all of the following conditions

The engine control module (ECM) and the malfunction indicator lamp (MIL) are operating correctly.
Diagnostic trouble codes (DTCs) are not stored.
The scan tool data is within the normal operating range. Refer to «Scan Tool Data List»(/cadillac/xlr/i-2003-2009/remont/testing-diagnostics/#engine-controls-46l-lh2-introduction-1-of-2__scan-tool-data-list) .
Verify the customer concern and locate the correct symptom. Inspect the items indicated under that symptom.
Several of the symptom procedures ask for a careful visual/physical inspection. This step is extremely important, and can lead to correcting a condition without further inspections and can save valuable time.
If the intermittent condition exists as a start and then stall, inspect for any DTCs related to the theft deterrent system. Refer to «Diagnostic System Check - Vehicle»(/cadillac/xlr/i-2003-2009/remont/oem-general-information/#vehicle-dtc-information) in Vehicle DTC Information.
Verify the proper installation of any of the following non-original equipment accessories: Lights Cellular phone Remote starter system Non-factory installed alarm

Use the following tables when diagnosing a symptom concern: «Poor Fuel Fill Quality»(/cadillac/xlr/i-2003-2009/remont/testing-diagnostics/#engine-controls-46l-lh2-troubleshooting__poor-fuel-fill-quality) «Hard Start»(/cadillac/xlr/i-2003-2009/remont/testing-diagnostics/#engine-controls-46l-lh2-troubleshooting__hard-start) «Surges/Chuggles»(/cadillac/xlr/i-2003-2009/remont/testing-diagnostics/#engine-controls-46l-lh2-troubleshooting__surgeschuggles) «Lack of Power, Sluggishness, or Sponginess»(/cadillac/xlr/i-2003-2009/remont/testing-diagnostics/#engine-controls-46l-lh2-troubleshooting__lack-of-power-sluggishness-or-sponginess) «Detonation/Spark Knock»(/cadillac/xlr/i-2003-2009/remont/testing-diagnostics/#engine-controls-46l-lh2-troubleshooting__detonationspark-knock) «Hesitation, Sag, Stumble»(/cadillac/xlr/i-2003-2009/remont/testing-diagnostics/#engine-controls-46l-lh2-troubleshooting__hesitation-sag-stumble) «Cuts Out, Misses»(/cadillac/xlr/i-2003-2009/remont/testing-diagnostics/#engine-controls-46l-lh2-troubleshooting__cuts-out-misses) «Poor Fuel Economy»(/cadillac/xlr/i-2003-2009/remont/testing-diagnostics/#engine-controls-46l-lh2-troubleshooting__poor-fuel-economy) «Rough, Unstable, or Incorrect Idle and Stalling»(/cadillac/xlr/i-2003-2009/remont/testing-diagnostics/#engine-controls-46l-lh2-troubleshooting__rough-unstable-or-incorrect-idle-and) «Dieseling, Run-On»(/cadillac/xlr/i-2003-2009/remont/testing-diagnostics/#engine-controls-46l-lh2-troubleshooting__dieseling-run-on) «Backfire»(/cadillac/xlr/i-2003-2009/remont/testing-diagnostics/#engine-controls-46l-lh2-troubleshooting__backfire)
If the condition can not be isolated using the appropriate table, refer to «Intermittent Conditions»(/cadillac/xlr/i-2003-2009/remont/testing-diagnostics/#engine-controls-46l-lh2-troubleshooting__intermittent-conditions) for further diagnosis.

Intermittent Conditions

Inspections	Action
DEFINITION: The condition is not currently present but is indicated in DTC history. OR There is a customer concern, but the symptom cannot currently be duplicated, if the condition is not DTC related.
Preliminary	Refer to Important Preliminary Inspection Before Starting in Symptoms - Engine Controls . The fault must be present to locate a problem using the DTC table. If a fault is intermittent, the use of DTC tables may result in the replacement of good parts.
Visual/Physical	This step is an important aid for locating a condition without extensive testing. Perform a thorough visual and physical inspection of the following components: Wiring harness for damage or cuts A misrouted harness that is too close to high voltage or high current devices such as the following: Secondary ignition components Motors Generators Vacuum hoses for the following conditions: Proper routing Proper connections Splits in the hose or the connections Kinks Air leaks at the throttle body mounting area-Refer to Throttle Body Inspection and Cleaning . Air leaks at the mass air flow (MAF) sensor and at the intake manifold Engine control module (ECM) and body grounds are clean and tight Battery connections are clean and tight Charging system for proper operation-Refer to Charging System Test in Engine Electrical.
Harness/Connector Test	Many intermittent open or shorted circuits come and go with harness and connector movement caused by vibration, engine torque, bumps and rough pavement, etc. Test for this type of condition by performing the applicable procedure from the following list: Move the related connectors and wiring while monitoring the appropriate scan tool data. Move the related connectors and wiring with the component commanded ON and OFF, with the scan tool. Observe the components operation. With the engine running, move the related connectors and wiring while monitoring engine operation. If harness or connector movement affects the data displayed, the component and system operation, or the engine operation, inspect and repair the harness or connections as necessary. Refer to Electrical Connections or Wiring in this table.
Electrical Connections or Wiring	Poor electrical connections and terminal tension or wiring faults cause most intermittents. Perform a careful inspection of the suspected circuit for the following: Inspect for incorrect mating of the connector halves, or terminals not fully seated in the connector body, backed-out. Inspect for improperly formed or damaged terminals. Test for incorrect terminal tension. Inspect for poor terminal to wire connections including terminals crimped over insulation. This requires removing the terminal from the connector body. Inspect for corrosion or water intrusion. Pierced or damaged insulation can allow moisture to enter the wiring. The conductor can corrode inside the insulation with little visible evidence. Look for swollen and stiff sections of wire in the suspect circuits. Inspect for wires that are broken inside the insulation. Inspect the harness for pinched, cut, or rubbed through wiring. Make sure the wiring does not come in contact with hot exhaust components. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.
ECM Power and Grounds	Poor power or ground connections can cause widely varying symptoms. Test all engine control module (ECM) power circuits. Many vehicles have multiple circuits supplying power to the ECM. Inspect connections at the ECM connectors, fuses, and any intermediate connections between the power source and the ECM or component. A test lamp or a DMM may indicate that voltage is present, but neither tests a circuits ability to carry sufficient current. Ensure that the circuit can carry the current necessary to operate the component. Refer to Power Distribution Schematics in Wiring Systems. Test all ECM ground and system ground circuits. The ECM may have multiple ground circuits. Other components in the system may have separate grounds that may also need to be tested. Make sure the ground connections are clean and tight at the grounding point. Inspect the connections at the component and in splice packs, where applicable. Ensure that the circuit can carry the current necessary to operate the component.
Temperature Sensitivity	An intermittent condition may occur only when the component is cold, or only when the component is hot. The heat that affects the circuit can be engine generated or due to a poor connection in the circuit or a high electrical load. Information from the customer may help to determine if the trouble follows a pattern that is temperature related. The Freeze Frame/Failure Records or Snapshot data may help with this type of intermittent condition, where applicable. If the intermittent is related to heat, review the data for a relationship with the following: High ambient temperatures Underhood/engine generated heat Circuit generated heat due to a poor connection, or high electrical load Higher than normal load conditions (towing, etc.) If the intermittent is related to cold, review the data for the following: Low ambient temperatures-In extremely low temperatures, ice may form in a connection or component. Inspect for water intrusion. The condition only occurs on a cold start. The condition goes away when the vehicle warms up.
Electromagnetic Interference (EMI) and Electrical Noise.	Some electrical components and circuits are sensitive to electromagnetic interference (EMI) or other types of electrical noise. Inspect for the following conditions: A misrouted harness that is too close to high voltage and high current devices such as secondary ignition components, motors, generator, etc. These components may induce electrical noise on a circuit that could interfere with normal circuit operation. Electrical system interference caused by a malfunctioning relay, ECM driven solenoid, or switch. They can cause a sharp electrical surge. Normally, the problem will occur when the malfunctioning component is operating. Incorrect installation of non-factory, aftermarket, add-on accessories such as lights, 2-way radios, amplifiers, electric motors, remote starters, alarm systems, cell phones, etc. Test for an open diode across the A/C compressor clutch and for other open diodes. Some relays may contain a clamping diode or resistor.
Incorrect ECM Programming	There are only a few situations where reprogramming an ECM is appropriate: An ECM from another vehicle is installed. Revised software/calibration files have been released for this vehicle. IMPORTANT: DO NOT reprogram the ECM with the SAME software/calibration files that are already present in the ECM. This is not an effective repair for any type of driveability problem. Verify that the ECM contains the correct software/calibration. If incorrect programming is found, reprogram the ECM with the most current software/calibration. Refer to Service Programming System (SPS) in Programming.
Duplicating Failure Conditions	If the previous tests were not successful, attempt to duplicate and/or capture the failure conditions. Freeze Frame/Failure Records data, where applicable, contains the conditions that were present when the DTC set. Review and record the Freeze Frame/Failure Records data. Clear any DTCs with a scan tool. Turn OFF the key and wait 15 seconds. Operate the vehicle under the same conditions that were noted in Freeze Frame/Failure Records. The vehicle must also be operating within the Conditions For Running the DTC. Refer to Conditions for Running the DTC in the supporting text of the DTC being diagnosed. Monitor DTC status for the DTC being tested. The scan tool will indicate Ran when the enabling conditions have been satisfied long enough for the DTC to run. The scan tool will also indicate whether the DTC passed or failed. An alternate method is to drive the vehicle with a DMM connected to a suspected circuit. An abnormal reading on the DMM when the problem occurs may help you locate the problem.
Scan Tool Snapshot	The scan tool can be set up to take a snapshot of the parameters available via serial data. The Snapshot function records live data over a period of time. The recorded data can be played back and analyzed. The scan tool can also graph parameters singly or in combinations of parameters for comparison. The snapshot can be triggered manually at the time the symptom is noticed or set up in advance to trigger when a DTC sets. An abnormal value captured in the recorded data may point to a system or component that needs to be investigated further. Refer to the scan tool user instructions for more information on the Snapshot function.

IMPORTANT
DO NOT reprogram the ECM with the SAME software/calibration files that are already present in the ECM. This is not an effective repair for any type of driveability problem.

Intermittent Conditions

Hard Start

Inspection/Test	Action
DEFINITION: Engine cranks OK, but does not start for a long time. Does eventually run, or may start but immediately dies.
Preliminary	Refer to Symptoms - Engine Controls . Inspect the engine control module (ECM) grounds for being clean, tight, and in the proper locations. Refer to Power and Grounding Component Views in Wiring Systems and Engine Controls Schematics . Search for bulletins. Verify that the driver is using the correct starting procedure as described in the owners manual.
Sensor/System	Verify that the engine coolant temperature (ECT) sensor is not shifted in value. Refer to Temperature Versus Resistance for resistance specifications. Verify proper operation of the manifold absolute pressure (MAP) sensor. Refer to Scan Tool Data Definitions .
Fuel System	Verify there is adequate fuel. A faulty in-tank sender check valve allows the fuel in the lines to drain back to the tank after the engine stops. Refer to Fuel System Diagnosis . Test the fuel injectors. Refer to Fuel Injector Balance Test with Special Tool and Fuel Injector Solenoid Coil Test . Inspect for incorrect fuel pressure. Refer to Fuel System Diagnosis . Inspect for a contaminated fuel condition. Refer to Alcohol/Contaminants-in-Fuel Diagnosis (without Special Tool) or Alcohol/Contaminants-in-Fuel Diagnosis (with Special Tool) .
Ignition System	Inspect for proper ignition voltage output with the J 26792 Spark Tester. Refer to Electronic Ignition (EI) System Diagnosis . Remove the spark plugs and inspect for the following conditions: Correct heat range Wet plugs Cracks Wear Improper gap Burned electrodes Heavy deposits Refer to Spark Plug Inspection . Determine the cause of the conditions before replacing the spark plugs. Inspect for loose ignition coil grounds. Inspect the ignition coils for cracks or carbon tracking. Soak the secondary ignition with water may help locate an intermittent problem. Ignition voltage will arc to ground when a secondary component is faulty.
Engine Mechanical	Inspect for the following conditions: Excessive oil in combustion chamber or leaking valve seals-Refer Oil Consumption Diagnosis in Engine Mechanical. Cylinder compression-Refer to Engine Compression Test in Engine Mechanical. Improper valve timing Worn rocker arms Broken or worn valve springs Combustion chambers for excessive carbon buildup-Clean the chambers using top engine cleaner. Follow the instructions on the can. Incorrect or damaged basic engine parts-Inspect the following components: The camshaft-Refer to Camshaft Cleaning and Inspection in Engine Mechanical. The cylinder heads-Refer to Cylinder Head Cleaning and Inspection in Engine Mechanical. The pistons, etc.-Refer to Piston, Connecting Rod, and Bearing Cleaning and Inspection in Engine Mechanical. Inspect for excessive crankshaft endplay that will cause the crankshaft position (CKP) sensor reluctor wheel to move out of alignment with the CKP sensor. Refer to Crankshaft and Bearing Cleaning and Inspection in Engine Mechanical. This could result in any of the following conditions: A no start A start and stall Erratic performance
Additional	Inspect for a restricted exhaust. Refer to Restricted Exhaust in Engine Exhaust. Inspect the air intake ducts for being collapsed, damaged, loose, improperly installed, or leaking, especially between the mass air flow (MAF) sensor and the throttle body.

Hard Start

Surges/Chuggles

Inspection/Tests	Action
DEFINITION: Engine power variation under steady throttle or cruise. Feels like the vehicle speeds up and slows down with no change in the accelerator pedal position.
Preliminary	Refer to Important Preliminary Inspections Before Starting in Symptoms - Engine Controls . Search for bulletins. Inspect the engine control module (ECM) grounds for being clean, tight, and in the proper locations. Refer to Power and Grounding Component Views in Wiring Systems and Engine Controls Schematics . Verify the driver understands the operation of the transmission torque converter clutch (TCC) and A/C compressor operation as explained in the owners manual. Inform the customer how the TCC and the A/C clutch operates.
Sensor/System	NOTE: Refer to Silicon Contamination of Heated Oxygen Sensors Notice in Cautions and Notices. Inspect the heated oxygen sensors (HO2S). The HO2S should respond quickly to different throttle positions. If they do not, inspect the HO2S for silicon or other contaminates from fuel or the use of improper RTV sealant. The sensors may have a white, powdery coating and result in a high but false signal voltage rich exhaust indication. The PCM will then reduce the amount of fuel delivered to the engine causing a severe driveability problem. Inspect the mass air flow (MAF) sensor for any contamination on the sensing element. Inspect the air intake ducts for being collapsed, damaged, loose, improperly installed, or leaking especially between the MAF sensor and the throttle body. Inspect for proper operation of the manifold absolute pressure (MAP) sensor. Refer to Scan Tool Data Definitions . Inspect for an engine coolant temperature (ECT) sensor that has shifted in value. Refer to Temperature Versus Resistance .
Fuel System	Test for incorrect fuel pressure. Refer to Fuel System Diagnosis . Test the fuel injectors. Refer to Fuel Injector Balance Test with Special Tool or Fuel Injector Solenoid Coil Test . Inspect for a contaminated fuel condition. Refer to Alcohol/Contaminants-in-Fuel Diagnosis (without Special Tool) or Alcohol/Contaminants-in-Fuel Diagnosis (with Special Tool) . Verify that each injector harness is connected to the correct injector or cylinder. Relocate injector harnesses as necessary. Inspect for the following conditions that may cause the engine to run rich: NOTE: Refer to Heated Oxygen and Oxygen Sensor Notice in Cautions and Notices. Water intrusion in the HO2S connector Engine oil contaminated by fuel-Refer to Alcohol/Contaminants-in-Fuel Diagnosis (without Special Tool) or Alcohol/Contaminants-in-Fuel Diagnosis (with Special Tool) . An evaporative emission (EVAP) canister purge condition Incorrect fuel pressure-Refer to Fuel System Diagnosis . Leaking fuel injectors-Refer to Fuel System Diagnosis . For proper operation of the MAP sensor-Refer to Scan Tool Data Definitions . For proper operation of the MAF sensor Blockage on the inlet screen of the MAF sensor Vacuum hoses that are split, kinked, or improperly connected An air intake duct that is collapsed or restricted An air filter that is dirty or restricted-Refer to Air Cleaner Element Replacement . Inspect for the following conditions that may cause the engine to run lean: NOTE: Refer to Heated Oxygen and Oxygen Sensor Notice in Cautions and Notices. Water intrusion in the HO2S connector An exhaust leak between the HO2S and the engine-Refer to Exhaust Leakage in Engine Exhaust. Vacuum leaks Incorrect fuel pressure-Refer to Fuel System Diagnosis . Restricted fuel injectors-Refer to Fuel Injector Balance Test with Special Tool . For proper operation of the MAP sensor-Refer to Scan Tool Data Definitions . For proper operation of the MAF sensor Fuel contamination-Refer to Alcohol/Contaminants-in-Fuel Diagnosis (without Special Tool) or Alcohol/Contaminants-in-Fuel Diagnosis (with Special Tool) . Vacuum hoses that are split, kinked, or improperly connected
Ignition System	Soak the secondary ignition system with water from a spray bottle. Soaking the secondary ignition system may help locate damaged or deteriorated components. Look and listen for arcing or misfiring as you apply the water. Test for proper ignition voltage output with the J 26792 Spark Tester. Refer to Electronic Ignition (EI) System Diagnosis . Remove the spark plugs and inspect for the following conditions: Correct heat range Wet plugs Cracks Wear Improper gap Burned electrodes Heavy deposits Refer to Spark Plug Inspection . An improper spark plug gap will cause a driveability problem. Gap the spark plugs using a wire gage gap tool. Refer to Ignition System Specifications and Spark Plug Replacement . Determine the cause of the fouling before replacing the spark plugs. Monitor the Misfire Current Counters while driving the vehicle within the conditions that the misfire occurred. Inspect for loose ignition coil grounds. Inspect the ignition coils for cracks or carbon tracking.
Additional Inspections	Visually and physically inspect vacuum hoses for splits, kinks, and proper connections and routing as shown on the Vehicle Emission Control Information label. Inspect the transmission TCC operation. Test the A/C clutch for proper operation. Refer to Symptoms - HVAC Systems - Automatic in HVAC Systems - Automatic. Inspect the exhaust system for possible restrictions. Refer to Restricted Exhaust in Engine Exhaust.

NOTE
Refer to Silicon Contamination of Heated Oxygen Sensors Notice in Cautions and Notices.

NOTE
Refer to Heated Oxygen and Oxygen Sensor Notice in Cautions and Notices.

NOTE
Refer to Heated Oxygen and Oxygen Sensor Notice in Cautions and Notices.

Surges/Chuggles

Lack of Power, Sluggishness, or Sponginess

Inspection/Tests	Action
DEFINITION: Engine delivers less than expected power. Little or no increase in speed when the accelerator pedal is pushed down part way.
Preliminary Inspections	Refer to Important Preliminary Inspections Before Starting in Symptoms - Engine Controls . Search for bulletins. Inspect the engine control module (ECM) grounds for being clean, tight, and in the proper locations. Refer to Power and Grounding Component Views in Wiring Systems and Engine Controls Schematics . Remove the air filter element and inspect for dirt or for restrictions. Refer to Air Cleaner Element Replacement and replace as necessary.
Fuel System	Test for incorrect fuel pressure. Refer to Fuel System Diagnosis . Inspect for a contaminated fuel condition. Refer to Alcohol/Contaminants-in-Fuel Diagnosis (without Special Tool) or Alcohol/Contaminants-in-Fuel Diagnosis (with Special Tool) . Test the fuel injectors. Refer to Fuel Injector Balance Test with Special Tool or Fuel Injector Solenoid Coil Test . Inspect for the following conditions that may cause the engine to run rich: NOTE: Refer to Heated Oxygen and Oxygen Sensor Notice in Cautions and Notices. Water intrusion in the heated oxygen sensor (HO2S) connector Engine oil contaminated by fuel An evaporative emission (EVAP) canister purge condition Incorrect fuel pressure-Refer to Fuel System Diagnosis . Leaking fuel injectors-Refer to Fuel System Diagnosis . Inspect for proper operation of the mass air flow (MAF) sensor. Refer to Scan Tool Data Definitions . Blockage on the inlet screen of the MAF sensor Vacuum hoses that are split, kinked, or improperly connected An air intake duct that is collapsed or restricted An air filter that is dirty or restricted-Refer to Air Cleaner Element Replacement . Inspect for the following conditions that may cause the engine to run lean: NOTE: Refer to Heated Oxygen and Oxygen Sensor Notice in Cautions and Notices. Water intrusion in the HO2S connector An exhaust leak between the HO2S and the engine-Refer to Exhaust Leakage in Engine Exhaust. Vacuum leaks Incorrect fuel pressure-Refer to Fuel System Diagnosis . Restricted fuel injectors-Refer to Fuel Injector Balance Test with Special Tool . Inspect for proper operation of the MAF sensor. Refer to Scan Tool Data Definitions . Fuel contamination-Refer to Alcohol/Contaminants-in-Fuel Diagnosis (without Special Tool) or Alcohol/Contaminants-in-Fuel Diagnosis (with Special Tool) . Vacuum hoses that are split, kinked, or improperly connected
Sensor/System	Use a scan tool in order to monitor the knock sensor (KS) system for excessive spark retard activity. Refer to Scan Tool Data Definitions . Inspect for a dirty or damaged air cleaner element. Inspect for a collapsed or damaged intake air duct.
Ignition System	Soak the secondary ignition system with water from a spray bottle. Soaking the secondary ignition system may help locate damaged or deteriorated components. Look and listen for arcing or misfiring as water is applied. Monitor the Misfire Current Counters while driving the vehicle within the conditions that the misfire occurred. Inspect for proper ignition voltage output with the J 26792 Spark Tester. Remove the spark plugs and inspect for the following conditions: Correct heat range Wet plugs Cracks Wear Improper gap Burned electrodes Heavy deposits Refer to Spark Plug Inspection . An improper spark plug gap will cause a driveability problem. Gap the spark plugs using a wire gage gap tool. Refer to Ignition System Specifications and Spark Plug Replacement . Determine the cause of the fouling before replacing the spark plugs. Inspect the spark plug boots for signs of arcing, cracks, carbon tracking, or damage. Inspect for loose ignition coil ground.
Engine Mechanical	Inspect for incorrect camshaft timing. Refer to Setting Camshaft Timing in Engine Mechanical. Inspect for excessive oil in the combustion chambers and leaking valve seals. Refer to Oil Consumption Diagnosis in Engine Mechanical. Test cylinder compression. Refer to Engine Compression Test in Engine Mechanical. Inspect for incorrect basic engine parts, including the following components: The camshaft-Refer to Camshaft Cleaning and Inspection in Engine Mechanical. The cylinder heads-Refer to Cylinder Head Cleaning and Inspection in Engine Mechanical. The pistons, etc.-Refer to Piston, Connecting Rod, and Bearing Cleaning and Inspection in Engine Mechanical. Inspect for excessive crankshaft endplay that will cause the crankshaft position (CKP) sensor reluctor wheel to move out of alignment with the CKP sensor. Refer to Crankshaft and Bearing Cleaning and Inspection in Engine Mechanical. This could result in any of the following conditions: A no start A start and stall Erratic performance
Additional Inspections	Inspect the exhaust system for possible restrictions. Refer to Restricted Exhaust in Engine Exhaust. Inspect the exhaust system for damaged or collapsed pipes. Inspect the mufflers for heat distress or internal failure. Inspect the transmission torque converter clutch (TCC) for proper operation.

NOTE
Refer to Heated Oxygen and Oxygen Sensor Notice in Cautions and Notices.

NOTE
Refer to Heated Oxygen and Oxygen Sensor Notice in Cautions and Notices.

Lack of Power, Sluggish or Spongy

Detonation/Spark Knock

Inspection/Tests	Action
DEFINITION: A mild to severe ping, usually worse under acceleration. The engine makes sharp metallic knocks that changes with throttle opening.
Preliminary Inspections	Refer to Symptoms - Engine Controls . Search for bulletins. Inspect the engine control module (ECM) grounds for being clean, tight, and in the proper locations. Refer to Power and Grounding Component Views in Wiring Systems and Engine Controls Schematics . If there are no engine mechanical faults, fill the fuel tank with a known high quality fuel that meets the vehicles minimum octane requirements. Road test the vehicle and re-evaluate the vehicles performance.
Fuel System	Test for incorrect fuel pressure. Refer to Fuel System Diagnosis . Test the fuel injectors. Refer to Fuel Injector Balance Test with Special Tool or Fuel Injector Solenoid Coil Test . Inspect for a contaminated fuel condition. Refer to Alcohol/Contaminants-in-Fuel Diagnosis (without Special Tool) or Alcohol/Contaminants-in-Fuel Diagnosis (with Special Tool) . Inspect for the following conditions that may cause the engine to run lean: NOTE: Refer to Heated Oxygen and Oxygen Sensor Notice in Cautions and Notices. Water intrusion in the heated oxygen sensor (HO2S) connector An exhaust leak between the HO2S and the engine-Refer to Exhaust Leakage in Engine Exhaust. Vacuum leaks Restricted fuel injectors-Refer to Fuel Injector Balance Test with Special Tool . Inspect for proper operation of the manifold absolute pressure (MAP) sensor. Refer to Scan Tool Data Definitions . Inspect for proper operation of the mass air flow (MAF) sensor. Refer to Scan Tool Data Definitions . Fuel contamination-Refer to Alcohol/Contaminants-in-Fuel Diagnosis (without Special Tool) or Alcohol/Contaminants-in-Fuel Diagnosis (with Special Tool) . Vacuum hoses that are split, kinked, or improperly connected
Sensor/System	Inspect for an engine coolant temperature (ECT) sensor that has shifted in value. Refer to Temperature Versus Resistance .
Ignition System	Soak the secondary ignition system with water from a spray bottle. Soaking the secondary ignition system may help locate damaged or deteriorated components. Look and listen for arcing or misfiring as water is applied. Inspect for proper ignition voltage output with the J 26792 Spark Tester. Refer to Electronic Ignition (EI) System Diagnosis . Remove the spark plugs and inspect for the following conditions: Correct heat range Wet plugs Cracks Wear Improper gap Burned electrodes Heavy deposits Refer to Spark Plug Inspection . Verify that the spark plugs are of the type. Refer to Ignition System Specifications . An improper spark plug gap will cause a driveability problem. Gap the spark plugs using a wire gage gap tool. Refer to Ignition System Specifications and Spark Plug Replacement . Determine the cause of the fouling before replacing the spark plugs. Inspect the spark plug boots for signs of arcing, cracks, carbon tracking, or damage. Inspect for loose ignition coil ground.
Engine Cooling System	Inspect for obvious overheating conditions: Low engine coolant-Refer to Loss of Coolant (LH2) or Loss of Coolant (LC3) in Engine Cooling. A faulty thermostat-Refer to Thermostat Diagnosis in Engine Cooling. Restricted air flow to the radiator or restricted coolant flow through the radiator An inoperative electric cooling fan-Refer to Cooling Fan Inoperative in Engine Cooling. Proper tension on the drive belts-Refer to Drive Belt Tensioner Diagnosis in Engine Mechanical. The correct coolant solution should be a 50/50 mix. Refer to Cooling System Description and Operation in Engine Cooling.
Engine Mechanical	Inspect for the following engine mechanical conditions: Excessive oil in combustion chamber-Leaking valve seals. Refer to Oil Consumption Diagnosis in Engine Mechanical. High cylinder compression-Refer to Engine Compression Test in Engine Mechanical. Combustion chambers for excessive carbon buildup-Clean the combustion chamber by using top engine cleaner. Follow the instructions on the can. Incorrect camshaft timing-Refer to Setting Camshaft Timing in Engine Mechanical. Inspect for incorrect basic engine parts. Inspect the following components: The camshaft-Refer to Camshaft Cleaning and Inspection in Engine Mechanical. The cylinder heads-Refer to Cylinder Head Cleaning and Inspection in Engine Mechanical. The pistons, etc.-Refer to Piston, Connecting Rod, and Bearing Cleaning and Inspection in Engine Mechanical. Refer to Symptoms - Engine Mechanical in Engine Mechanical.
Additional Inspections	Inspect the park/neutral position (PNP) switch operation. Inspect the transmission torque converter clutch (TCC) operation. The TCC applying too soon can cause the engine to spark knock.

NOTE
Refer to Heated Oxygen and Oxygen Sensor Notice in Cautions and Notices.

Detonation/Spark Knock

Hesitation, Sag, Stumble

Inspection/Tests	Action
DEFINITION: Momentary lack of response as the accelerator is pushed down. Can occur at any vehicle speed. Usually more pronounced when first trying to make the vehicle move, as from a stop. May cause the engine to stall if severe enough.
Preliminary	Refer to Important Preliminary Inspections Before Starting in Symptoms - Engine Controls . Search for bulletins. Inspect the engine control module (ECM) grounds for being clean, tight, and in the proper locations. Refer to Power and Grounding Component Views in Wiring Systems, and Engine Controls Schematics .
Sensor/System	NOTE: Refer to Silicon Contamination of Heated Oxygen Sensors Notice in Cautions and Notices. Inspect the heated oxygen sensors (HO2S). The HO2S should respond quickly to different throttle positions. If they do not, inspect the HO2S for silicon or other contaminates from fuel or the use of improper RTV sealant. The sensors may have a white, powdery coating and result in a high but false signal voltage rich exhaust indication. The PCM will then reduce the amount of fuel delivered to the engine causing a severe driveability problem. Inspect the air intake ducts for being collapsed, damaged, loose, improperly installed, or leaking especially between the mass air flow (MAF) sensor and the throttle body. Inspect for proper operation of the manifold absolute pressure (MAP) sensor. Refer to Scan Tool Data Definitions . Verify that the engine coolant temperature (ECT) sensor is not shifted in value. Refer to Temperature Versus Resistance for resistance specifications. Inspect the MAF sensor and intake air system for proper operation. Refer to Scan Tool Data Definitions .
Fuel System	Test for incorrect fuel pressure. Refer to Fuel System Diagnosis . Inspect for a restricted fuel filter. Refer to Fuel System Diagnosis . Inspect for a contaminated fuel condition. Refer to Alcohol/Contaminants-in-Fuel Diagnosis (without Special Tool) or Alcohol/Contaminants-in-Fuel Diagnosis (with Special Tool) . Test the fuel injector Refer to Fuel Injector Balance Test with Special Tool or Fuel Injector Solenoid Coil Test . Inspect for the following conditions that may cause the engine to run rich: NOTE: Refer to Heated Oxygen and Oxygen Sensor Notice in Cautions and Notices. Water intrusion in the HO2S connector Engine oil contaminated by fuel An evaporative emission (EVAP) canister purge condition Incorrect fuel pressure-Refer to Fuel System Diagnosis . Leaking fuel injectors-Refer to Fuel System Diagnosis . Inspect for proper operation of the MAP sensor. Refer to Scan Tool Data Definitions . Inspect for proper operation of the MAF sensor. Refer to Scan Tool Data Definitions . Vacuum hoses that are split, kinked, or improperly connected An air intake duct that is collapsed or restricted An air filter that is dirty or restricted-Refer to Air Cleaner Element Replacement . Inspect for the following conditions that may cause the engine to run lean: NOTE: Refer to Heated Oxygen and Oxygen Sensor Notice in Cautions and Notices. Water intrusion in the HO2S connector An exhaust leak between the HO2S and the engine-Refer to Exhaust Leakage in Engine Exhaust. Vacuum leaks Incorrect fuel pressure-Refer to Fuel System Diagnosis . Restricted fuel injectors-Refer to Fuel Injector Balance Test with Special Tool . Inspect for proper operation of the MAF sensor. Refer to Scan Tool Data Definitions . Fuel contamination-Refer to Alcohol/Contaminants-in-Fuel Diagnosis (without Special Tool) or Alcohol/Contaminants-in-Fuel Diagnosis (with Special Tool) . Vacuum hoses that are split, kinked, or improperly connected
Ignition System	Soak the secondary ignition system with water from a spray bottle. Soaking the secondary ignition system may help locate damaged or deteriorated components. Look and listen for arcing or misfiring as you apply water. Monitor the Misfire Current Counters while driving the vehicle in the conditions that the misfire occurred. Test for proper ignition voltage output with the J 26792 Spark Tester. Refer to Electronic Ignition (EI) System Diagnosis . Remove the spark plugs and check for the following conditions: Correct heat range Wet plugs Cracks Wear Improper gap Burned electrodes Heavy deposits Refer to Spark Plug Inspection . An improper spark plug gap will cause a driveability problem. Gap the spark plugs using a wire gage gap tool. Refer to Ignition System Specifications and Spark Plug Replacement . Determine the cause of the fouling before replacing the spark plugs. Inspect the spark plug boots for signs of arcing, cracks, carbon tracking, or damage. Inspect for loose ignition coil ground. Refer to Power and Grounding Component Views in Wiring Systems.
Engine Cooling System	Inspect the engine thermostat for proper operation and for correct heat range. Refer to Thermostat Diagnosis in Engine Cooling.
Engine Mechanical	Inspect for excessive crankshaft endplay that will cause the crankshaft position (CKP) sensor reluctor wheel to move out of alignment with the CKP sensor. Refer to Crankshaft and Bearing Cleaning and Inspection in Engine Mechanical. This could result in any of the following conditions: A no start A start and stall Erratic performance
Additional Inspections	Inspect the generator output voltage. Refer to Charging System Test in Engine Electrical.

NOTE
Refer to Silicon Contamination of Heated Oxygen Sensors Notice in Cautions and Notices.

NOTE
Refer to Heated Oxygen and Oxygen Sensor Notice in Cautions and Notices.

NOTE
Refer to Heated Oxygen and Oxygen Sensor Notice in Cautions and Notices.

Hesitation, Sag, Stumble

Cuts Out, Misses

Inspections	Action
DEFINITION: Steady pulsation or jerking that follows engine speed, usually more pronounced as engine load increases. This condition is not normally felt above 1,500 RPM or 48 km/h (30 mph). The exhaust has a steady spitting sound at idle or low speed.
Preliminary	Refer to Important Preliminary Inspections Before Starting in Symptoms - Engine Controls . Search for bulletins. Verify that the engine control module (ECM) grounds are clean, tight, and in the proper locations. Refer to Power and Grounding Component Views in Wiring Systems and Engine Controls Schematics . Remove the air filter element and inspect for dirt and for restrictions. Refer to Air Cleaner Element Replacement . Replace as necessary.
Fuel System	Test the fuel injectors. Refer to Fuel Injector Balance Test with Special Tool or Fuel Injector Solenoid Coil Test . Test for incorrect fuel pressure. Refer to Fuel System Diagnosis . Inspect for proper operation of the evaporative emission (EVAP) control system. Refer to Evaporative Emission Control System Description . Inspect for a contaminated fuel condition. Refer to Alcohol/Contaminants-in-Fuel Diagnosis (without Special Tool) or Alcohol/Contaminants-in-Fuel Diagnosis (with Special Tool) . Inspect for the following conditions that may cause the engine to run rich: NOTE: Refer to Heated Oxygen and Oxygen Sensor Notice in Cautions and Notices. Water intrusion in the heated oxygen sensor (HO2S) connector Engine oil contaminated by fuel An EVAP canister purge condition Incorrect fuel pressure-Refer to Fuel System Diagnosis . Leaking fuel injectors-Refer to Fuel System Diagnosis . Inspect for proper operation of the manifold absolute pressure (MAP) sensor. Refer to Scan Tool Data Definitions . Inspect for proper operation of the mass air flow (MAF) sensor. Refer to Scan Tool Data Definitions . Blockage on the inlet screen of the MAF sensor. Vacuum hoses that are split, kinked, or improperly connected An air intake duct that is collapsed or restricted An air filter that is dirty or restricted-Refer to Air Cleaner Element Replacement . Inspect for the following conditions that may cause the engine to run lean: NOTE: Refer to Heated Oxygen and Oxygen Sensor Notice in Cautions and Notices. Water intrusion in the HO2S connector An exhaust leak between the HO2S and the engine-Refer to Exhaust Leakage in Engine Exhaust. Vacuum leaks Incorrect fuel pressure-Refer to Fuel System Diagnosis . Restricted fuel injectors-Refer to Fuel Injector Balance Test with Special Tool . Inspect for proper operation of the MAP sensor. Refer to Scan Tool Data Definitions . Inspect for proper operation of the MAF sensor. Refer to Alcohol/Contaminants-in-Fuel Diagnosis (without Special Tool) or Alcohol/Contaminants-in-Fuel Diagnosis (with Special Tool) . Fuel contamination-Refer to Alcohol/Contaminants-in-Fuel Diagnosis (without Special Tool) or Alcohol/Contaminants-in-Fuel Diagnosis (with Special Tool) . Vacuum hoses that are split, kinked, or improperly connected
Sensor/System	Monitor the knock sensor (KS) system for excessive spark retard activity, with a scan tool. Inspect the air intake ducts for being collapsed, damaged, loose, improperly installed, or leaking especially between the MAF sensor and the throttle body. Verify that the engine coolant temperature (ECT) sensor is not shifted in value. Refer to Temperature Versus Resistance . Inspect for a vacuum leak. Inspect the crankcase ventilation operation. Refer to Crankcase Ventilation System Inspection/Diagnosis in Engine Mechanical.
Ignition System	Soak the secondary ignition system with water from a spray bottle. Soaking the secondary ignition system may help locate damaged or deteriorated components. Look and listen for arcing or misfiring as you apply water. Monitor the Misfire Current Counters while driving the vehicle in the conditions that the misfire occurred. Performing a Cylinder Balance Test with a scan tool may also help isolate which cylinder may be misfiring. Test for proper ignition voltage output. Refer to Electronic Ignition (EI) System Diagnosis . Remove the spark plugs and inspect for the following conditions: Correct heat range Wet plugs Cracks Wear Improper gap Burned electrodes Heavy deposits Refer to Spark Plug Inspection . An improper spark plug gap will cause a driveability problem. Gap the spark plugs using a wire gage gap tool. Refer to Ignition System Specifications . Determine the cause of the fouling before replacing the spark plugs. Visually and physically inspect for the following conditions: The spark plug boots for signs of arcing, cracks, carbon tracking, or damage The spark plug boots for proper engagement to spark plug The ignition coils for cracks or carbon tracking
Engine Mechanical	Inspect engine mechanical for the following conditions: Test compression-Refer to Engine Compression Test in Engine Mechanical. Sticking or leaking valves Worn camshaft lobes Valve timing Worn rocker arms-Refer to Valve Rocker Arms Cleaning and Inspection in Engine Mechanical. Broken valve springs-Refer to Cylinder Head Cleaning and Inspection in Engine Mechanical. Excessive oil in combustion chamber-Leaking valve seals For more information refer to one of the following procedures: Engine Compression Test Symptoms - Engine Mechanical Oil Consumption Diagnosis For incorrect basic engine parts inspect the following components: The camshaft-Refer to Camshaft Cleaning and Inspection in Engine Mechanical. The cylinder heads-Refer to Cylinder Head Cleaning and Inspection in Engine Mechanical. The pistons, etc.-Refer to Piston, Connecting Rod, and Bearing Cleaning and Inspection in Engine Mechanical. Inspect for excessive crankshaft endplay that will cause the crankshaft position (CKP) sensor reluctor wheel to move out of alignment with the CKP sensor. Refer to Crankshaft and Bearing Cleaning and Inspection in Engine Mechanical. This could result in any of the following conditions: A no start A start and stall Erratic performance Refer to Symptoms - Engine Mechanical in Engine Mechanical for diagnostic procedures.
Additional Inspections	Inspect the exhaust system for possible restrictions. Inspect for the following conditions: The exhaust system for damaged or collapsed pipes The mufflers for heat distress or possible internal failure For possible plugged catalytic converters- Refer to Restricted Exhaust in Engine Exhaust. Electromagnetic interference (EMI) on the reference circuit can cause an engine misfire condition. A sudden increase in indicated RPM with little change in actual engine RPM change indicates EMI is present. Inspect for high voltage components near ignition control circuits if a condition exists. Inspect the intake manifold and the exhaust manifold passages for casting flash. Refer to Intake Manifold Cleaning and Inspection or Exhaust Manifold Cleaning and Inspection - Left Side and Exhaust Manifold Cleaning and Inspection - Right Side in Engine Mechanical

NOTE
Refer to Heated Oxygen and Oxygen Sensor Notice in Cautions and Notices.

NOTE
Refer to Heated Oxygen and Oxygen Sensor Notice in Cautions and Notices.

Cuts Out, Misses

Poor Fuel Economy

Inspections	Action
DEFINITION: Fuel economy, as measured by an actual road test, is noticeably lower than expected. Also, fuel economy is noticeably lower than the economy was on this vehicle at one time, as previously shown by an actual road test.
Preliminary	Refer to Important Preliminary Inspections Before Starting in Symptoms - Engine Controls . Search for bulletins. Inspect the engine control module (ECM) grounds for being clean, tight, and in the proper locations. Refer to Power and Grounding Component Views in Wiring Systems and Engine Controls Schematics . Discuss driving habits with the owner. Is the A/C ON or the Defroster mode ON full time? Are the tires at the correct pressure? Are the wheels and tires the correct size? Are there excessively heavy loads being carried? Is the acceleration rate too much, too often? Remove the air filter element and inspect for dirt or for restrictions. Refer to Air Cleaner Element Replacement . Replace as necessary.
Fuel System	Discuss with the owner the type, quality, and alcohol content of the fuel. Oxygenated fuels have lower energy and may deliver reduced fuel economy. Test the fuel injectors. Refer to Fuel Injector Balance Test with Special Tool or Fuel Injector Solenoid Coil Test . Test for incorrect fuel pressure. Refer to Fuel System Diagnosis . Inspect for a contaminated fuel condition. Refer to Alcohol/Contaminants-in-Fuel Diagnosis (without Special Tool) or Alcohol/Contaminants-in-Fuel Diagnosis (with Special Tool) . Inspect that each fuel injector harness is connected to the correct injector and cylinder. Relocate the injector harnesses as necessary. Inspect for the following conditions that may cause the engine to run rich: NOTE: Refer to Heated Oxygen and Oxygen Sensor Notice in Cautions and Notices. Water intrusion in the heated oxygen sensor (HO2S) connector Engine oil contaminated by fuel An evaporative emission (EVAP) canister purge condition Incorrect fuel pressure-Refer to Fuel System Diagnosis . Leaking fuel injectors-Refer to Fuel System Diagnosis . For proper operation of the manifold absolute pressure (MAP) sensor-Refer to Scan Tool Data Definitions . For proper operation of the mass air flow (MAF) sensor Blockage on the inlet screen of the MAF sensor Vacuum hoses that are split, kinked, or improperly connected An air intake duct that is collapsed or restricted An air filter that is dirty or restricted-Refer to Air Cleaner Element Replacement .
Sensor/System	Inspect the air intake system and crankcase for air leaks. Verify that the engine coolant temperature (ECT) sensor is not shifted in value. Refer to Temperature Versus Resistance for resistance specifications. Inspect for an inaccurate speedometer. Refer to Symptoms - Instrument Panel, Gages and Console in Instrument Panel, Gages, and Console. Use a scan tool in order to monitor the knock sensor (KS) system for excessive spark retard activity. Refer to Scan Tool Data Definitions .
Ignition System	Inspect for proper ignition voltage output with the J 26792 Spark Tester. Refer to Electronic Ignition (EI) System Diagnosis . Remove the spark plugs and inspect for the following conditions: Wet plugs Cracks Wear Improper gap Burned electrodes Heavy deposits Refer to Spark Plug Inspection . An improper spark plug gap will cause a driveability problem. Gap the spark plugs using a wire gage gap tool. Refer to Spark Plug Replacement and Ignition System Specifications . Determine the cause of the fouling before replacing the spark plugs. Soaking the secondary ignition system with water from a spray bottle may help locate damaged or deteriorated components. Look and listen for arcing or misfiring as you apply water. Inspect for loose ignition coil grounds. Refer to Power and Grounding Component Views in Wiring Systems.
Engine Cooling System	Inspect the engine coolant level for being low. Refer to Loss of Coolant (LH2) or Loss of Coolant (LC3) in Engine Cooling. Inspect the engine thermostat for proper operation and for the correct heat range. Refer to Thermostat Diagnosis in Engine Cooling.
Engine Mechanical	Inspect engine mechanical for the following conditions: Compression Sticking or leaking valves Worn camshaft lobes Valve timing Worn rocker arms Broken valve springs Excessive oil in combustion chamber-Leaking valve seals. For more information refer to one of the following procedures: Engine Compression Test Symptoms - Engine Mechanical Oil Consumption Diagnosis For incorrect basic engine parts inspect for the following components: The camshaft-Refer to Camshaft Cleaning and Inspection in Engine Mechanical. The cylinder heads-Refer to Cylinder Head Cleaning and Inspection in Engine Mechanical. The pistons, etc.-Refer to Piston, Connecting Rod, and Bearing Cleaning and Inspection in Engine Mechanical. Refer to Symptoms - Engine Mechanical in Engine Mechanical for diagnostic procedures.
Additional Inspections	Visually and physically check the vacuum hoses for splits, kinks, and proper connections and routing as shown on Vehicle Emission Control Information label. Inspect the transmission torque converter clutch (TCC) operation. The scan tool should indicate a RPM drop, when the system commands the TCC ON. Inspect the exhaust system for a possible restriction. Inspect for the following conditions: The exhaust system for damaged or collapsed pipes The mufflers for heat distress or possible internal failure For possible plugged catalytic converters-Refer to Restricted Exhaust in Engine Exhaust. Electromagnetic interference (EMI) on the reference circuit can cause an engine miss condition. A scan tool can usually detect EMI by monitoring the engine RPM. A sudden increase in RPM with little change in actual engine RPM change indicates EMI is present. Inspect for high voltage components, near ignition control circuits, if a condition exists. Inspect the brake system for dragging or improper operation. Refer to Symptoms - Hydraulic Brakes in Hydraulic Brakes. Verify that the vehicle operator does not drive with a foot on the brake pedal.

NOTE
Refer to Heated Oxygen and Oxygen Sensor Notice in Cautions and Notices.

Poor Fuel Economy

Poor Fuel Fill Quality

Problem	Causes
Definition: During the fueling process a continual, occasional or no fuel nozzle shut-off condition has occurred.
Difficult to fill	Fill limiter vent valve stuck closed Evaporative emission (EVAP) canister restricted EVAP vent valve stuck closed Restricted vapor lines High Reid vapor pressure or high fuel temperature Fuel filler hose is pinched or kinked Ignition switch ON
Over fill	Pressure relief valve is stuck open or leaking Fill limiter vent valve stuck open or leaking
Premature shut-off of the fuel dispensing nozzle	Fill limiter vent valve stuck closed EVAP canister restricted EVAP vent valve stuck closed Restricted vapor lines High Reid vapor pressure or high fuel temperature Ignition switch ON (EVAP vent valve closed)
Fuel Spitback	Restricted EVAP canister High Reid vapor pressure or high fuel temperature Ignition switch ON

Poor Fuel Fill Quality

Rough, Unstable, or Incorrect Idle and Stalling

Inspections	Action
DEFINITION: Engine runs unevenly at idle. If severe, the engine or vehicle may shake. Engine idle speed may vary in RPM. Either condition may be severe enough to stall the engine.
Preliminary Inspections	Refer to Important Preliminary Inspections Before Starting in Symptoms - Engine Controls . Search for bulletins. Inspect the engine control module (ECM) grounds for being clean, tight, and in the proper locations. Refer to Power and Grounding Component Views in Wiring Systems. Remove and inspect the air filter element for dirt or for restrictions. Refer to Air Cleaner Element Replacement . Replace as necessary.
Fuel System	Test the fuel injectors. Refer to Fuel Injector Balance Test with Special Tool or Fuel Injector Solenoid Coil Test . Inspect for incorrect fuel pressure. Refer to Fuel System Diagnosis . Inspect for a contaminated fuel condition. Refer to Alcohol/Contaminants-in-Fuel Diagnosis (without Special Tool) or Alcohol/Contaminants-in-Fuel Diagnosis (with Special Tool) . Inspect that each fuel injector harness is connected to the correct injector/cylinder. Relocate fuel injector harnesses as necessary. Inspect for the following conditions that may cause the engine to run rich: NOTE: Refer to Heated Oxygen and Oxygen Sensor Notice in Cautions and Notices. Water intrusion in the heated oxygen sensor (HO2S) connector Engine oil contaminated by fuel An evaporative emission (EVAP) canister purge condition Incorrect fuel pressure-Refer to Fuel System Diagnosis . Leaking fuel injectors-Refer to Fuel System Diagnosis . Inspect for proper operation of the manifold absolute pressure (MAP) sensor. Refer to Scan Tool Data Definitions . Inspect for proper operation of the mass air flow (MAF) sensor. Refer to Scan Tool Data Definitions . Blockage on the inlet screen of the MAF sensor Vacuum hoses that are split, kinked, or improperly connected An air intake duct that is collapsed or restricted An air filter that is dirty or restricted-Refer to Air Cleaner Element Replacement . Inspect for the following conditions that may cause the engine to run lean: NOTE: Refer to Heated Oxygen and Oxygen Sensor Notice in Cautions and Notices. Water intrusion in the HO2S connector An exhaust leak between the HO2S and the engine-Refer to Exhaust Leakage in Engine Exhaust. Vacuum leaks Incorrect fuel pressure-Refer to Fuel System Diagnosis . Restricted fuel injectors-Refer to Fuel Injector Balance Test with Special Tool . Inspect for proper operation of the MAP sensor. Refer to Scan Tool Data Definitions . Inspect for proper operation of the MAF sensor. Refer to Scan Tool Data Definitions . Fuel contamination-Refer to Alcohol/Contaminants-in-Fuel Diagnosis (without Special Tool) or Alcohol/Contaminants-in-Fuel Diagnosis (with Special Tool) . Vacuum hoses that are split, kinked, or improperly connected
Sensor/System	Inspect the air intake ducts for being collapsed, damaged areas, looseness, improper installation, or leaking especially between the MAF sensor and the throttle body. Inspect the Transaxle Range Switch input with the vehicle in drive and the gear selector in drive or overdrive. Use a scan tool in order to monitor the knock sensor (KS) system for excessive spark retard activity. Refer to Scan Tool Data Definitions .
Ignition System	Inspect for proper ignition voltage output with the J 26792 Spark Tester. Refer to Electronic Ignition (EI) System Diagnosis for the procedure. Remove spark plugs and check for the following conditions: Wet plugs Cracks Wear Improper gap Burned electrodes Heavy deposits In order to properly inspect the spark plugs or to correct a condition, refer to the following procedures: Ignition System Specifications Spark Plug Inspection Spark Plug Replacement An improper spark plug gap will cause a driveability problem. Gap the spark plugs using a wire gage gap tool. Determine the cause of the fouling before replacing the spark plugs. Inspect the spark plug boots for signs of arcing, cracks, carbon tracking, or damage. Soak the secondary ignition system with water from a spray bottle. Soaking the secondary ignition system may help locate damaged or deteriorated components. Look and listen for arcing or misfiring as you apply water. Monitor the Misfire Current Counters while driving the vehicle in the conditions that the misfire occurred. Inspect for loose ignition coil grounds. Refer to Power and Grounding Component Views in Engine Electrical.
Engine Mechanical	Inspect engine mechanical for the following conditions: Compression Sticking or leaking valves Worn camshaft lobes Valve timing Worn rocker arms Broken valve springs Excessive oil in combustion chamber or leaking valve seals For more information, refer to one or more of the following procedures in Engine Mechanical: Engine Compression Test Symptoms - Engine Mechanical Oil Consumption Diagnosis For incorrect basic engine parts. Inspect the following components: The camshaft-Refer to Camshaft Cleaning and Inspection in Engine Mechanical. The cylinder heads-Refer to Cylinder Head Cleaning and Inspection in Engine Mechanical. The pistons, etc.-Refer to Piston, Connecting Rod, and Bearing Cleaning and Inspection in Engine Mechanical. Inspect for excessive crankshaft endplay that will cause the crankshaft position (CKP) sensor reluctor wheel to move out of alignment with the CKP sensor. Refer to Crankshaft and Bearing Cleaning and Inspection in Engine Mechanical. This could result in any of the following conditions: A no start A start and stall Erratic performance Refer to Symptoms - Engine Mechanical in Engine Mechanical for diagnosis procedures.
Additional Inspections	Inspect the exhaust system for the following possible restrictions: The exhaust system for damaged or collapsed pipes The mufflers for heat distress or possible internal failure For possible plugged catalytic converters-Refer to Restricted Exhaust in Engine Exhaust. Electromagnetic interference (EMI) on the reference circuit can cause an engine miss condition. A scan tool can usually detect EMI by monitoring the engine RPM. A sudden increase in RPM with little change in actual engine RPM change indicates that EMI is present. If a problem exists, inspect routing of high voltage components near the ignition control circuits. Inspect for faulty motor mounts. Refer to Engine Mount Inspection in Engine Mechanical. Inspect the intake manifold and the exhaust manifold passages for casting flash. Refer to Intake Manifold Cleaning and Inspection , or Exhaust Manifold Cleaning and Inspection - Left Side and Exhaust Manifold Cleaning and Inspection - Right Side in Engine Mechanical.

NOTE
Refer to Heated Oxygen and Oxygen Sensor Notice in Cautions and Notices.

NOTE
Refer to Heated Oxygen and Oxygen Sensor Notice in Cautions and Notices.

Rough, Unstable, or Incorrect Idle and Stalling

Dieseling, Run-On

Inspections	Action
DEFINITION: Engine continues to run after key is turned OFF, but runs very rough. If the engine runs smooth, inspect the ignition switch and the ignition switch adjustment.
Preliminary Inspections	Refer to Important Preliminary Inspections Before Starting in Symptoms - Engine Controls . Search for bulletins. Verify that the engine control module (ECM) grounds are clean, tight, and in the proper locations. Refer to Power and Grounding Component Views in Wiring Systems and Engine Controls Schematics .
Fuel System	Test the fuel injectors. Refer to Fuel Injector Balance Test with Special Tool and Fuel Injector Solenoid Coil Test .
Additional Inspections	Remove the spark plugs and inspect for the following conditions: Correct heat range Heavy deposits Refer to Spark Plug Inspection .

Dieseling, Run-On

Backfire

Inspections	Actions
DEFINITION Fuel ignites in the intake manifold or in the exhaust system, making a loud popping noise.
Preliminary Inspections	Refer to Symptoms - Engine Controls . Search for bulletins. Inspect the engine control module (ECM) grounds for being clean, tight, and in the proper locations. Refer to Power and Grounding Component Views and Engine Controls Schematics in Wiring Systems.
Fuel System	Test for correct fuel pressure. Refer to Fuel System Diagnosis . Inspect for a contaminated fuel condition. Refer to Alcohol/Contaminants-in-Fuel Diagnosis (without Special Tool) or Alcohol/Contaminants-in-Fuel Diagnosis (with Special Tool) . Verify that each injector harness is connected to the correct injector or cylinder. Relocate injector harnesses as necessary.
Sensor/System	Inspect the air intake system and crankcase for air leaks. Use a scan tool in order to monitor the knock sensor (KS) system for excessive spark retard activity.
Ignition System	Inspect for proper ignition voltage output with the J 26792 Spark Tester. Refer to Electronic Ignition (EI) System Diagnosis . Inspect the coils for cracks, carbon tracking/arcing. Inspect spark plug boots for signs of arcing, cracks, carbon tracking, or damage. Remove spark plugs and inspect for the following conditions: Wet plugs Cracks Wear Improper gap Burned electrodes Heavy deposits Refer to Spark Plug Inspection . An improper spark plug gap will cause a driveability problem. Gap the spark plugs using a wire gage gap tool. Refer to Ignition System Specifications and Spark Plug Replacement . Determine the cause of the fouling before replacing the spark plugs. Soak the secondary ignition system with water from a spray bottle. Soaking the secondary ignition system may help locate damaged or deteriorated components. Look and listen for arcing or misfiring as you apply the water. Monitor the Misfire Current Counters while driving the vehicle in the conditions that the misfire occurred. Inspect for loose ignition coil ground. Refer to Power and Grounding Component Views in Engine Electrical.
Engine Cooling System	Inspect the engine coolant level for being low. Refer to Loss of Coolant (LH2) or Loss of Coolant (LC3) in Engine Cooling. Inspect the engine thermostat for proper operation and for the correct heat range. Refer to Thermostat Diagnosis in Engine Cooling.
Engine Mechanical	Inspect engine mechanical for the following conditions: Compression-Refer to Engine Compression Test in Engine Mechanical. Sticking or leaking valves Worn camshaft lobes Valve timing Worn rocker arms Broken valve springs Excessive oil in combustion chamber or leaking valve seals. Refer to Oil Consumption Diagnosis in Engine Mechanical. For incorrect basic engine parts. Inspect the following components: The camshaft-Refer to Camshaft Cleaning and Inspection in Engine Mechanical. The cylinder heads-Refer to Cylinder Head Cleaning and Inspection in Engine Mechanical. The pistons, etc.-Refer to Piston, Connecting Rod, and Bearing Cleaning and Inspection in Engine Mechanical. Refer to Symptoms - Engine Mechanical in Engine Mechanical for diagnosis procedures.
Additional Inspections	Visually and physically inspect the vacuum hoses for splits, kinks, and proper connections and routing as shown on the Vehicle Emission Control Information label. Inspect the intake manifold and the exhaust manifold passages for casting flash. Refer to Intake Manifold Cleaning and Inspection or Exhaust Manifold Cleaning and Inspection - Left Side and Exhaust Manifold Cleaning and Inspection - Right Side in Engine Mechanical. Inspect the transmission torque converter clutch (TCC) operation. The scan tool should indicate an RPM drop when the TCC is commanded ON. Inspect the exhaust system for possible restrictions. Inspect the following conditions: The exhaust system for damaged or collapsed pipes The mufflers for heat distress or possible internal failure For possible plugged catalytic converters-Refer to Restricted Exhaust in Engine Exhaust. Electromagnetic interference (EMI) on the reference circuit can cause an engine miss condition. A scan tool can usually detect EMI by monitoring the engine RPM. A sudden increase in RPM with little change in actual engine RPM change may indicate that EMI is present. If a problem exists, inspect for high voltage components near the ignition control circuits.

Backfire

Circuit Description

Voltage is supplied to the malfunction indicator lamp (MIL) internally by the instrument panel cluster (IPC). The engine control module (ECM) turns the MIL ON by grounding the MIL control circuit. There should be a steady MIL with the ignition ON and the engine OFF.

MIL Operation

The MIL is located on the IPC.

MIL Function

The MIL informs the driver that a malfunction has occurred and the vehicle should be taken in for service as soon as possible.
The MIL illuminates during a bulb test and a system test.
A DTC will be stored if a MIL is requested by the ECM.

MIL Illumination

The MIL will illuminate with the ignition switch ON and the engine not running.
The MIL will turn OFF when the engine is started.
The MIL will remain ON if the self-diagnostic system has detected a malfunction.
The MIL may turn OFF if the malfunction is not present.
If the MIL is illuminated and then the engine stalls, the MIL will remain illuminated as long as the ignition switch is ON.
If the MIL is not illuminated and the engine stalls, the MIL will not illuminate until the ignition switch is cycled OFF, then ON.

Step	Action	Values	Yes	No
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Control Module Connector End Views or Engine Controls Connector End Views
1	Did you perform the Diagnostic System Check - Vehicle?		Go to Step 2	Go to Diagnostic System Check - Vehicle in Vehicle DTC Information
2	Turn ON the ignition, with the engine OFF. Is the instrument cluster completely inoperative?		Go to Symptoms - Instrument Panel, Gages and Console in Instrument Panel, Gages, and Console	Go to Step 3
3	Turn ON the ignition, with the engine OFF. Command the MIL ON and OFF with a scan tool. Does the malfunction indicator lamp (MIL) turn ON and OFF when commanded with a scan tool?		Go to Intermittent Conditions	Go to Step 4
4	Inspect the fuse that supplies voltage to the cluster. Is the fuse open?		Go to Step 11	Go to Step 5
5	Turn OFF the ignition. Remove the fuse that supplies voltage to the cluster. Disconnect the engine control module (ECM). Turn ON the ignition with the engine OFF. Measure the voltage from the MIL control circuit in the ECM harness connector to a good ground. Is the voltage less than the specified value?	1 V	Go to Step 6	Go to Step 12
6	Turn OFF the ignition. Install the fuse that supplies voltage to the cluster. Turn ON the ignition with the engine OFF. Connect a 3-amp fused jumper wire between the MIL control circuit in the ECM harness connector and a good ground. Is the MIL illuminated?		Go to Step 10	Go to Step 7
7	Turn OFF the ignition. Remove the instrument panel cluster (IPC). Refer to Instrument Cluster Replacement in Instrument Panel, Gages, and Console. Turn ON the ignition. Probe the voltage supply circuit of the IPC harness connector with a test lamp that is connected to a good ground. Does the test lamp illuminate?		Go to Step 8	Go to Step 13
8	Test the MIL control circuit for an open or high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct a condition?		Go to Step 16	Go to Step 9
9	Test for an intermittent and for a poor connection at the IPC. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition?		Go to Step 16	Go to Step 14
10	Test for an intermittent and for a poor connection at the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition?		Go to Step 16	Go to Step 15
11	Test all circuits and components that use this voltage supply for excessive current draw. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?		Go to Step 16
12	Repair the short to voltage in the MIL control circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair?		Go to Step 16
13	Repair the open in the voltage supply circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair?		Go to Step 16
14	Replace the IPC. Refer to Instrument Cluster Replacement in Instrument Panel, Gages, and Console. Did you complete the replacement?		Go to Step 16
15	Replace the ECM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement?		Go to Step 16
16	Turn the ignition OFF for 30 seconds. Start the engine. Does the MIL operate correctly?		Go to Step 17	Go to Step 2
17	Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed?		Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information	System OK

Malfunction Indicator Lamp (MIL) Inoperative

Voltage is supplied to the malfunction indicator lamp (MIL) internally by the instrument panel cluster (IPC). The engine control module (ECM) turns the MIL ON by grounding the MIL control circuit.

The MIL is located on the IPC.

MIL Function

The MIL informs the driver that a malfunction has occurred and the vehicle should be taken in for service as soon as possible.
The MIL illuminates during a bulb test and a system test.
A DTC will be stored if a MIL is requested by the diagnostic.

MIL Illumination

The MIL will illuminate with the ignition switch ON and the engine not running.
The MIL will turn OFF when the engine is started.
The MIL will remain ON if the self-diagnostic system has detected a malfunction.
The MIL may turn OFF if the malfunction is not present.
If the MIL is illuminated and then the engine stalls, the MIL will remain illuminated as long as the ignition switch is ON.
If the MIL is not illuminated and the engine stalls, the MIL will not illuminate until the ignition switch is cycled OFF, then ON.

Test Description

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

2: This step determines if the condition is with the MIL control circuit or the ECM.

Step	Action	Yes	No
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Control Module Connector End Views or Engine Controls Connector End Views
1	Did you perform the Diagnostic System Check - Vehicle?	Go to Step 2	Go to Diagnostic System Check - Vehicle in Vehicle DTC Information
2	Turn OFF the ignition. Disconnect the engine control module (ECM). Turn ON the ignition, with the engine OFF. Observe the malfunction indicator lamp (MIL). Is the MIL illuminated?	Go to Step 3	Go to Step 5
3	Remove the instrument panel cluster (IPC). Refer to Instrument Cluster Replacement in Instrument Panel, Gages, and Console. Test the MIL control circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition?	Go to Step 6	Go to Step 4
4	Replace the IPC. Refer to Instrument Cluster Replacement in Instrument Panel, Gages, and Console. Did you complete the replacement?	Go to Step 6
5	Replace the ECM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement?	Go to Step 6
6	Turn the ignition OFF for 30 seconds. Start the engine. Does the MIL operate correctly?	Go to Step 7	Go to Step 2
7	Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed?	Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information	System OK

Malfunction Indicator Lamp (MIL) Always On

Description

The Engine Cranks but Does Not Run diagnostic table is an organized approach to identifying a condition that causes an engine to not start. The diagnostic table directs the service technician to the appropriate system diagnosis. The diagnostic table assumes the following conditions are met

The battery is completely charged. Refer to «Battery Inspection/Test»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system) in Engine Electrical.
The engine cranking speed is acceptable. Refer to «Engine Cranks Slowly»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system__engine-cranks-slowly) in Engine Electrical.
There is adequate fuel in the fuel tank.

Step	Action	Values	Yes	No
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Control Module Connector End Views or Engine Controls Connector End Views
1	Did you perform the Diagnostic System Check - Vehicle ?		Go to Step 2	Go to Diagnostic System Check - Vehicle in Vehicle DTC Information
2	Turn ON the ignition, with the engine OFF. Observe the DTC information with a scan tool. Does the scan tool display DTCs P0102, P0113, P0201, P0202, P0203, P0204, P0205, P0206, P0207, P0208, P0230, P0231, P0232, P0261, P0264, P0267, P0270, P0273, P0276, P0279, P0282, P0335, P0336, P0601, P0602, P0604, P0606, P0627, P0628, P0629, P0686, P0687, P0689, P0690, P1251, P1252, P1253, P1254, P1626, P1631, or P2636?		Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information	Go to Step 3
3	Does the scan tool display any vehicle theft deterrent (VTD) DTCs?		Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information	Go to Step 4
4	Probe both test points of the FUEL fuse located in the underhood electrical center using a test lamp connected to a good ground. Does the test lamp illuminate on at least one test point of the fuse?		Go to Step 5	Go to Ignition 1 Relay Diagnosis
5	Probe both test points of the ODD INJ fuse and both test points of the EVEN INJ fuse located in the underhood fuse block using a test lamp connected to a good ground. Does the test lamp illuminate on both test points of both fuses?		Go to Step 6	Go to Fuel Injector Circuit Diagnosis
6	Observe the engine speed parameter on the scan tool, while cranking the engine. Does the scan tool display the specified value?	0 RPM	Go to Step 10	Go to Step 7
7	Turn OFF the ignition Remove the ignition coil assembly from either bank. Do not disconnect any electrical connectors from the ignition coil assembly. Refer to Ignition Coil Replacement - Bank 1 or Ignition Coil Replacement - Bank 2 . Install the J 36012-A Ignition Diagnostic Harness. Install the J 26792 Spark Tester on one of the spark plug jumper wires. Attach the clamp end of the spark tester to a good ground. Crank the engine with the remaining spark plug jumper wires connected. Repeat steps 5-7 for each remaining cylinder on this bank. Repeat the procedure for the opposite bank. Reassemble the vehicle after performing the procedure. Did the spark tester spark on all cylinders?		Go to Step 8	Go to Electronic Ignition (EI) System Diagnosis
8	IMPORTANT: The engine coolant temperature (ECT) must be below the operating temperature in order to avoid irregular fuel pressure readings due to hot soak fuel boiling. Install a J 34730-1A Fuel Pressure Gage. Refer to Fuel Pressure Gage Installation and Removal . Turn ON the ignition, with the engine OFF. IMPORTANT: The fuel pump may need to be commanded ON a few times in order to obtain the highest possible fuel pressure. Command the fuel pump ON with a scan tool. Observe the fuel pressure while the fuel pump is operating. Is the fuel pressure within the specified range?	380-427 kPa (55-62 psi)	Go to Step 9	Go to Fuel System Diagnosis
9	Inspect for the following conditions: Collapsed air intake duct Restricted air filter element-Refer to Air Cleaner Element Replacement . Spark plugs for being fouled-Refer to Spark Plug Replacement and Spark Plug Inspection . If the spark plugs are fouled, determine what caused the condition. Contaminated fuel-Refer to Alcohol/Contaminants-in-Fuel Diagnosis (without Special Tool) Alcohol/Contaminants-in-Fuel Diagnosis (with Special Tool) . Engine mechanical condition, for example, broken timing chain, low compression. Refer to Setting Camshaft Timing and Engine Compression Test in Engine Mechanical. Restricted exhaust system-Refer to Restricted Exhaust in Engine Exhaust. An ECT sensor that has shifted in value-Refer to Temperature Versus Resistance Temperature vs Resistance. Compare the manifold absolute pressure (MAP) parameter to another vehicle. The parameters should be close in value. Refer to DTC P0106 . Did you complete the action?		Go to Step 16
10	Disconnect the engine control module (ECM). Refer to Engine Control Module Replacement . Test for a short between the following circuits: The mass air flow (MAF) sensor 12-volt reference circuit and the intake air temperature (IAT) sensor 5-volt reference circuit-Refer to Circuit Testing in Wiring Systems. The MAF sensor 12-volt reference circuit and the IAT sensor low reference circuit-Refer to Circuit Testing in Wiring Systems. Did you find and correct the condition?		Go to Step 16	Go to Step 11
11	Connect the ECM. Turn ON the ignition with the engine OFF. Disconnect a camshaft position sensor. Install a DMM between the camshaft position sensor 12-volt reference circuit and a good ground. Monitor the DMM while disconnecting the MAF/IAT sensor. If the voltage changes while disconnecting the MAF/IAT sensor, replace the MAF/IAT sensor. Did you replace the sensor?		Go to Step 16	Go to Step 12
12	Connect the camshaft position sensor. Install a DMM between the MAF sensor 12-volt reference circuit and a good ground. Monitor the DMM while disconnecting all other sensors connected to the 12-volt reference circuit, one at a time. If the voltage changes when one of the sensors are disconnected, replace the sensor. Did you replace a sensor?		Go to Step 16	Go to Step 13
13	Test the 12-volt reference circuits of the following components for a short to ground. Refer to Circuit Testing in Wiring Systems. MAF/IAT airflow sensor Crankshaft position (CKP) sensor CMP sensor bank 1 exhaust CMP sensor bank 2 exhaust CMP sensor bank 1 intake CMP sensor bank 2 intake Did you find and correct the condition?		Go to Step 16	Go to Step 14
14	Test for shorted terminals and poor connections at the ECM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition?		Go to Step 16	Go to Step 15
15	Replace the ECM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement?		Go to Step 16
16	Clear the DTCs with a scan tool. Attempt to start the engine. Does the engine start and continue to operate?		Go to Step 17	Go to Step 2
17	Idle the engine. Allow the engine to reach operating temperature. Observe the DTC information with a scan tool. Are any DTCs displayed?		Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information	System OK

IMPORTANT
The engine coolant temperature (ECT) must be below the operating temperature in order to avoid irregular fuel pressure readings due to hot soak fuel boiling.

IMPORTANT
The fuel pump may need to be commanded ON a few times in order to obtain the highest possible fuel pressure.

Engine Cranks but Does Not Run

The ignition 1 relay is a normally open relay. The relay armature is held in the open position by spring tension. Battery positive voltage is supplied directly to the ignition 1 relay coil and the armature contact at all times. The engine control module (ECM) supplies the ground path to the relay coil control circuit, via an internal integrated circuit, called an output driver module. When the ECM commands the relay ON, the relay coil creates an electromagnetic field. This electromagnetic field overcomes the spring tension and pulls the armature contact into stationary contact of the relay load circuit. The closing of the relay contacts allows current to flow from the battery to the following fuses and relay

OXY SENSOR FUSE
FUEL PUMP FUSE
EMISSION FUSE
ODD INJECTORS FUSE
EVEN INJECTORS FUSE
ETC FUSE
A/C RELAY

When the ignition switch is turned to the OFF position, power is interrupted to the output driver module in the ECM, and the ignition 1 relay electromagnetic field collapses. This action allows the spring tension pulling on the armature to separate from the relay load circuit contact, which interrupts current flow to the fuses and relay.

If the ignition 1 relay fails to close, the engine will crank, but will not run. The GMLAN and class II data communications will be available, with the use of a CANdi module and scan tool.

Diagnostic Aids

The ignition 1 relay will remain powered up for 15 seconds after the ignition switch is turned OFF.
The ignition 1 relay system diagnosis table assumes that the vehicle battery is fully charged. Refer to «Battery Inspection/Test»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system) in Engine Electrical.
The underhood fuse block terminal locations correspond to the following ignition 1 relay circuits: F13 - Ignition 1 voltage circuit F14 - Ignition 1 relay coil control circuit H13 - Battery positive voltage to the ignition 1 relay coil H14 - Battery positive voltage to the ignition 1 relay armature

Step	Action	Yes	No
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Control Module Connector End Views or Engine Controls Connector End Views
1	Did you perform the Diagnostic System Check-Vehicle?	Go to Step 2	Go to Diagnostic System Check - Vehicle in Vehicle DTC Information
2	Are DTCs P0686, P0687, P0689 or P0690 set?	Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information	Go to Step 3
3	Turn ON the ignition, with the engine OFF. Remove the underhood fuse block cover. Probe the following fuses with a test lamp that is connected to a good ground. Refer to Troubleshooting with a Test Lamp in Wiring Systems. OXY SENSOR FUSE FUEL PUMP FUSE EMISSION FUSE ODD INJECTOR FUSE EVEN INJECTOR FUSE ETC FUSE Does the test lamp illuminate on at least one test point of each fuse?	Go to Step 6	Go to Step 4
4	Turn OFF the ignition. Remove the ignition 1 relay from the underhood junction block with the J 43244 Relay Puller Pliers. Refer to Relay Replacement (Within an Electrical Center) or Relay Replacement (Attached to Wire Harness) in Wiring Systems. Connect a 20-amp fused jumper wire from the battery positive voltage terminal for the ignition 1 relay armature at the underhood fuse block to the relay load circuit terminal at the underhood fuse block. Refer to Using Fused Jumper Wires in Wiring Systems. Probe the following fuses with a test lamp that is connected to a good ground: OXY SENSOR FUSE FUEL PUMP FUSE EMISSION FUSE ODD INJECTOR FUSE EVEN INJECTOR FUSE ETC FUSE Does the test lamp illuminate on at least one test point of each fuse?	Go to Intermittent Conditions	Go to Step 5
5	Replace the underhood fuse block. Refer to Underhood Electrical Center or Junction Block Replacement in Wiring Systems. Did you complete the replacement?	Go to Step 6
6	Replace any open fuses. Turn OFF the ignition for 30 seconds. Attempt to start the engine. Does the engine start and run?	Go to Step 7	Go to Intermittent Conditions
7	Clear the DTCs with a scan tool. Operate the vehicle for 5 minutes. Does a DTC set during this ignition cycle?	Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information

Ignition 1 Relay Diagnosis

When you turn the ignition switch ON, the control module energizes the fuel pump relay which applies power to the in-tank fuel pump. The fuel pump relay will remain ON as long as the engine is running or cranking and the control module is receiving reference pulses. If no reference pulses are present, the control module de-energizes the fuel pump relay within 2 seconds after the ignition is turned ON or the engine is stopped.

Listen for an audible hiss from the fuel pump when the fuel pump relay is commanded ON. A vibration in the fuel feed line when the fuel pump relay is commanded ON indicates that the fuel pump is operating.

For an intermittent condition, refer to Testing for Intermittent Conditions and Poor Connections .

The numbers below refer to the step numbers on the diagnostic table

3: This step determines if the condition is located on the coil side or the switch side of the circuit.
10: This step verifies that the fuel pump fuse is providing voltage to the fuel pump relay.
11: This step jumps the fuel pump relay in order to activate the fuel pump.
15: This step determines if the condition with the circuit is intermittent. If the fuse does not open, inspect the supply voltage circuit between the fuse and the fuel pump for an intermittent condition.

Step	Action	Yes	No
Schematic Reference: Engine Controls Schematics
1	Did you perform the Diagnostic System Check - Vehicle?	Go to Step 2	Go to Diagnostic System Check - Vehicle
2	Turn ON the ignition, with the engine OFF. Command the fuel pump relay ON and OFF with a scan tool. Does the fuel pump turn ON and OFF?	Go to Diagnostic Aids	Go to Step 3
3	Command the fuel pump relay ON and OFF with a scan tool. Do you hear a click when you command the fuel pump relay ON and OFF?	Go to Step 5	Go to Step 4
4	Turn OFF the ignition. Remove the fuel pump relay. Probe the ground circuit for the fuel pump relay with a test lamp connected to battery voltage. Did the test lamp illuminate?	Go to Step 21	Go to Step 16
5	Turn ON the ignition, with the engine OFF. Does the fuel pump operate continuously?	Go to Step 6	Go to Step 7
6	Turn OFF the ignition. Disconnect the fuel pump relay. Turn ON the ignition, with the engine OFF. Does the fuel pump operate continuously?	Go to Step 17	Go to Step 20
7	Is the fuel pump fuse open?	Go to Step 8	Go to Step 10
8	Disconnect the fuel pump harness in-line connector located near the fuel tank. Refer to Power and Grounding Connector End Views . Test the supply voltage circuit of the fuel pump for a grounded circuit. Refer to Wiring Repairs and Connector Repairs . Replace the fuel pump fuse, if necessary. Did you find and correct the condition?	Go to Step 21	Go to Step 9
9	Lower the left fuel tank, if necessary. Refer to Fuel Tank Fuel Pump Module Replacement - Left Side . Test the fuel tank electrical harness for damage or for a grounded circuit. Refer to Circuit Testing and Wiring Repairs . Replace the fuel pump fuse, if necessary. Did you find and correct the condition?	Go to Step 21	Go to Step 15
10	Turn OFF the ignition. Disconnect the fuel pump relay. Turn ON the ignition, with the engine OFF. Probe the battery positive voltage circuit of the fuel pump relay with a test lamp connected to a good ground. Does the test lamp illuminate?	Go to Step 11	Go to Step 18
11	Connect a 15-amp fused jumper wire between the battery positive voltage circuit and the fuel pump supply circuit of the fuel pump relay. Does the fuel pump operate?	Go to Step 16	Go to Step 12
12	Disconnect the fuel pump harness in-line connector located near the fuel tank. Refer to Power and Grounding Connector End Views . Test the supply voltage circuit of the fuel pump for an open or for high resistance between the fuel pump relay and the in-line connector. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition?	Go to Step 21	Go to Step 13
13	IMPORTANT: Inspect the ground circuit for being tight, for corrosion on the terminals, or for damage to the wiring harness. Test the ground circuit of the fuel pump for an open or for high resistance between the body pass through connector and the ground. Refer to Circuit Testing and Wiring Repairs .Did you find and correct the condition?	Go to Step 21	Go to Step 14
14	Lower the left fuel tank. Refer to Fuel Tank Fuel Pump Module Replacement - Left Side . Test for an intermittent and poor connection at the fuel tank module connector. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . Did you find and correct the condition?	Go to Step 21	Go to Step 19
15	Connect all disconnected components. Install a new fuel pump fuse. Command the fuel pump ON with a scan tool. Is the fuel pump fuse open?	Go to Step 19	Go to Diagnostic Aids
16	Test for an open or an intermittent condition in the fuel pump relay ground circuit. Refer to Circuit Testing , Wiring Repairs , Testing for Intermittent Conditions and Poor Connections , and Connector Repairs . Did you find and correct the condition?	Go to Step 21	Go to Step 20
17	Repair the supply voltage circuit of the fuel pump for a short to voltage. Refer to Wiring Repairs . Did you complete the repair?	Go to Step 21
18	Repair the battery positive voltage circuit of the fuel pump relay for an open. Refer to Wiring Repairs . Did you complete the repair?	Go to Step 21
19	IMPORTANT: Inspect for poor connections at the fuel pump, within the fuel tank, before replacing the fuel pump. Replace the left fuel tank module. Refer to Fuel Tank Fuel Pump Module Replacement - Left Side . Replace the fuel pump fuse, if necessary. Did you complete the replacement?	Go to Step 21
20	Replace the fuel pump relay. Did you complete the replacement?	Go to Step 21
21	Operate the system in order to verify the repair. Did you correct the condition?	System OK	Go to Step 2

IMPORTANT
Inspect the ground circuit for being tight, for corrosion on the terminals, or for damage to the wiring harness.

IMPORTANT
Inspect for poor connections at the fuel pump, within the fuel tank, before replacing the fuel pump.

Fuel Pump Electrical Circuit Diagnostic

System Description

When you turn the ignition switch to the ON position, the control module enables the fuel pump relay, which in turn powers the fuel pump. The fuel pump remains ON as long as the engine is cranking or running, and the control module receives ignition reference pulses. If there are no ignition reference pulses, the control module shuts the fuel pump OFF within 2 seconds after the ignition was switched to the ON position, or if the engine stops.

The fuel system is a returnless on-demand design. The fuel pressure regulator is a part of the fuel tank module, eliminating the need for a return pipe from the engine. A returnless fuel system reduces the internal temperature of the fuel tank by not returning hot fuel from the engine to the fuel tank. Reducing the internal temperature of the fuel tank results in lower evaporative emissions.

Two fuel tanks store the fuel supply. An electric turbine style fuel pump attaches to the fuel tank module inside the left fuel tank. The fuel pump supplies high pressure fuel through the fuel filter and the fuel feed pipe to the fuel injection system. The fuel pump provides fuel at a higher rate of flow than is needed by the fuel injection system. The fuel pump also supplies fuel to a Venturi pump located on the bottom of the left fuel tank module. The function of the Venturi pump is to fill the left fuel tank module reservoir. The primary fuel pressure regulator, a part of the left fuel tank module, maintains the correct fuel pressure to the fuel injection system. The left fuel tank module contains a reverse flow check valve. The check valve, the primary fuel pressure regulator, and the secondary fuel pressure regulator maintain fuel pressure in the fuel feed pipe and the fuel rail in order to prevent long cranking times.

The fuel pump also supplies a small amount of pressurized fuel through the auxiliary fuel feed pipe to the siphon jet pump inside the right fuel tank. The pressurized fuel creates a Venturi action inside the siphon jet pump. The Venturi action causes the fuel to be drawn out of the right fuel tank. The fuel transfers from the right fuel tank to the left fuel tank through the auxiliary fuel return pipe. The auxiliary fuel return pipe inside the left fuel tank contains an anti-siphon hole in order to prevent fuel from siphoning from the left fuel tank into the right fuel tank. Both the auxiliary fuel feed pipe and the auxiliary fuel return pipe are located inside the convoluted stainless steel crossover hose.

The right fuel tank module contains a secondary fuel pressure regulator. The secondary fuel pressure regulator has a lower set point than the primary regulator in order to allow fuel to flow to the siphon jet pump on the right fuel tank module. When the engine is shut off, the pressure in the feed pipes immediately drops to the secondary regulator set point. This prevents the siphon jet pump from operating and in turn prevents the equalization of the left and right fuel tanks. The secondary fuel pressure regulator maintains fuel pressure in the auxiliary fuel feed pipe which reduces the time to prime the siphon jet pump. The pressurization also reduces fuel vaporization and boiling in the auxiliary fuel feed pipe.

Step	Action	Value(s)	Yes	No
Schematic Reference: Fuel Hose/Pipes Routing Diagram
1	Did you perform the Diagnostic System Check - Vehicle?		Go to Step 2	Go to Diagnostic System Check - Vehicle
2	Observe the Fuel Level Sensor Left and Right parameters with a scan tool. Is the Fuel Level Sensor Left parameter less than the specified value?	0.8 V	Go to Step 3	Go to Step 4
3	IMPORTANT: Venting of fuel vapors during refueling is done through the fill limiter vent valve (FLVV) located on the right fuel tank. The fuel system may be difficult to fill if the Fuel Level Sensor Right parameter is more than 2.3 volts, indicating that the right fuel tank is full. The addition of fuel may be easier when done at a slow rate with a portable gasoline container. Add the specified amount of fuel.Did you complete the action?	15 L (4 gal)	Go to Step 4
4	IMPORTANT: The engine coolant temperature must be below the operating temperature in order to avoid irregular fuel pressure readings due to hot soak fuel boiling. Install a J 34730-1A Fuel Pressure Gage. Refer to Fuel Pressure Gage Installation and Removal . Turn ON the ignition, with the engine OFF. IMPORTANT: The fuel pump may need to be commanded ON a few times in order to obtain the highest possible fuel pressure. Command the fuel pump ON with a scan tool. Observe the J 34730-1A with the fuel pump running. Is the fuel pressure within the specified value?	380-427 kPa (55-62 psi)	Go to Step 5	Go to Step 12
5	IMPORTANT: The fuel pressure will decrease when the fuel pump stops operating. After the fuel pump stops operating, the fuel pressure should stabilize and remain constant. Observe the J 34730-1A for 5 minutes.Does the fuel pressure decrease to less than the specified value?	350 kPa (51 psi)	Go to Step 11	Go to Step 6
6	Observe the Fuel Level Sensor Right parameter. Is the Fuel Level Sensor Right parameter less than the specified value?	1 V	Go to Step 7	Go to Step 9
7	Fill the fuel system until the Fuel Level Sensor Right parameter is more than the specified value. Did you complete the action?	1 V	Go to Step 8
8	Drain the left fuel tank until the Fuel Level Sensor Left parameter is less than the specified value. Refer to Fuel Tank Draining . Did you complete the action?	1.5 V	Go to Step 9
9	Start the engine. Observe the Fuel Level Sensor Left and the Fuel Level Sensor Right parameters with a scan tool for 5 minutes. Does the Fuel Level Sensor Right parameter decrease while the Fuel Level Sensor Left parameter increases?		Go to Step 10	Go to Step 15
10	Operate the vehicle within the conditions to reproduce the original symptoms. Observe the O2 and the fuel trim parameters with a scan tool. Do the scan tool parameters indicate a lean condition?		Go to Step 13	Go to Symptoms - Engine Controls
11	Turn OFF the ignition. Relieve the fuel pressure. Refer to Fuel Pressure Relief . Disconnect the fuel feed hose from the fuel rail pipe. Refer to Metal Collar Quick Connect Fitting Service . Install the J 37287 Fuel Line Shut-off Adapter between the fuel hose and the fuel rail pipe. Open the valve on the J 37287 . Turn ON the ignition, with the engine OFF. Command the fuel pump ON with a scan tool. Bleed the air from the fuel pressure gage. Command the fuel pump ON and then OFF with a scan tool. Close the valve on the fuel line shut-off adapter. Observe the fuel pressure gage for 1 minute. Does the fuel pressure remain constant?		Go to Step 21	Go to Step 28
12	Is the fuel pressure more than the specified value?	427 kPa (62 psi)	Go to Step 29	Go to Step 13
13	Inspect the following components for a restriction: The fuel feed pipe The fuel feed rear pipe Did you find and correct the condition?		Go to Step 32	Go to Step 14
14	Inspect the harness connectors, the circuits of the fuel pump, and the fuel pump control module for high resistance. Refer to Circuit Testing . Did you find and correct the condition?		Go to Step 32	Go to Step 21
15	Remove the fuel tank crossover tube/hose. Refer to Fuel Tank Crossover Tube/Hose Replacement . Inspect the auxiliary fuel feed pipe and the auxiliary fuel return pipe inside of the crossover tube/hose for a restriction. Did you find and correct the condition?		Go to Step 32	Go to Step 16
16	Connect the J 41413-200 Evaporative Emissions System Tester (EEST) to one end of the 5/16-inch auxiliary fuel feed pipe inside of the crossover tube/hose using the appropriate hose and the J 41413-311 Brass Cone Adapter from the J 41413-300 EVAP Cap/Plug Kit. See Special Tools . Apply nitrogen to the auxiliary fuel feed pipe. Cap the other end of the 5/16-inch auxiliary fuel feed pipe inside of the crossover tube/hose using the J 41413-306 Small Red Cap from the J 41413-300 . See Special Tools . Observe the flow meter on the J 41413-200 . Does the flow meter indicate a leak?		Go to Step 31	Go to Step 17
17	Connect the J 41413-200 to one end of the 3/8-inch auxiliary fuel return pipe inside of the crossover hose using the appropriate hose and the J 41413-311 from the J 41413-300 . See Special Tools . Apply nitrogen to the auxiliary fuel return pipe. Cap the other end of the 3/8-inch auxiliary fuel return pipe inside of the crossover hose using the J 41413-307 from the J 41413-300 . See Special Tools . Observe the flow meter on the J 41413-200 . Does the flow meter indicate a leak?		Go to Step 31	Go to Step 18
18	Inspect for damaged O-rings at the crossover hose to fuel tank connections. Did you find and correct the condition?		Go to Step 32	Go to Step 19
19	Connect the J 41413-200 to the 5/16-inch auxiliary fuel feed pipe inside of the left fuel tank using the appropriate hose and the J 41413-311 from the J 41413-300 . See Special Tools . Apply nitrogen to the auxiliary fuel feed pipe. Observe the flow meter on the J 41413-200 . Does the flow meter indicate a leak?		Go to Step 26	Go to Step 20
20	Connect the J 41413-200 to the 5/16-inch auxiliary fuel feed pipe inside of the right fuel tank using the appropriate hose and the J 41413-311 from the J 41413-300 . See Special Tools . Apply nitrogen to the auxiliary fuel feed pipe. Observe the flow meter on the J 41413-200 . Does the flow meter indicate a leak?		Go to Step 27	Go to Step 30
21	Relieve the fuel pressure. Refer to Fuel Pressure Relief . Remove the J 37287 , if previously installed. Connect the fuel feed hose to the fuel rail pipe, if previously disconnected. Remove the fuel tank crossover tube/hose. Refer to Fuel Tank Crossover Tube/Hose Replacement . Connect the J 41413-200 to one end of the 5/16-inch auxiliary fuel feed pipe inside of the crossover tube/hose using the appropriate hose and the J 41413-311 from the J 41413-300 . See Special Tools . Apply nitrogen to the auxiliary fuel feed pipe. Cap the other end of the 5/16-inch auxiliary fuel feed pipe inside of the crossover tube/hose using the J 41413-306 from the J 41413-300 . See Special Tools . Observe the flow meter on the J 41413-200 . Does the flow meter indicate a leak?		Go to Step 31	Go to Step 22
22	Connect the J 41413-200 to one end of the 3/8-inch auxiliary fuel return pipe inside of the crossover tube/hose using the appropriate hose and the J 41413-311 from the J 41413-300 . See Special Tools . Apply nitrogen to the auxiliary fuel return pipe. Cap the other end of the 3/8-inch auxiliary fuel return pipe inside of the crossover tube/hose using the J 41413-307 from the J 41413-300 . See Special Tools . Observe the flow meter on the J 41413-200 . Does the flow meter indicate a leak?		Go to Step 31	Go to Step 23
23	Inspect for damaged O-rings at the crossover hose to fuel tank connections. Did you find and correct the condition?		Go to Step 32	Go to Step 24
24	Connect the J 41413-200 to the 5/16-inch auxiliary fuel feed pipe inside of the right fuel tank using the appropriate hose and the J 41413-311 from the J 41413-300 . See Special Tools . Apply nitrogen to the auxiliary fuel feed pipe. Observe the flow meter on the J 41413-200 . Does the flow meter indicate a leak?		Go to Step 27	Go to Step 25
25	Connect the J 41413-200 to the 5/16-inch auxiliary fuel feed pipe inside of the left fuel tank using the appropriate hose and the J 41413-311 from the J 41413-300 . See Special Tools . Apply nitrogen to the auxiliary fuel feed pipe. Observe the flow meter on the J 41413-200 . Does the flow meter indicate a leak?		Go to Step 26	Go to Step 29
26	Remove the left fuel tank module. Refer to Fuel Tank Fuel Pump Module Replacement - Left Side . Inspect the auxiliary fuel feed and return pipes inside of the left fuel tank for damage or restriction. Did you find and correct the condition?		Go to Step 32	Go to Step 29
27	Remove the right fuel tank module. Refer to Fuel Tank Fuel Pump Module Replacement - Right Side . Inspect the auxiliary fuel feed and return pipes inside of the right fuel tank for damage or restriction. Did you find and correct the condition?		Go to Step 32	Go to Step 30
28	Turn OFF the ignition. Raise the fuel rail, with the fuel line connected. Refer to Fuel Injection Fuel Rail Assembly Replacement . Turn ON the ignition, with the engine OFF. Command the fuel pump ON with a scan tool. Locate and replace the leaking fuel injector. Refer to Fuel Injector Replacement . Did you complete the replacement?		Go to Step 32
29	Replace the left fuel tank module. Refer to Fuel Tank Fuel Pump Module Replacement - Left Side . Did you complete the replacement?		Go to Step 32
30	Replace the right fuel tank module. Refer to Fuel Tank Fuel Pump Module Replacement - Right Side . Did you complete the replacement?		Go to Step 32
31	Replace the fuel tank crossover tube/hose. Refer to Fuel Tank Crossover Tube/Hose Replacement . Did you complete the replacement?		Go to Step 32
32	Operate the system in order to verify the repair. Did you correct the condition?		System OK	Go to Step 4

IMPORTANT
Venting of fuel vapors during refueling is done through the fill limiter vent valve (FLVV) located on the right fuel tank. The fuel system may be difficult to fill if the Fuel Level Sensor Right parameter is more than 2.3 volts, indicating that the right fuel tank is full. The addition of fuel may be easier when done at a slow rate with a portable gasoline container.

IMPORTANT
The engine coolant temperature must be below the operating temperature in order to avoid irregular fuel pressure readings due to hot soak fuel boiling.

IMPORTANT
The fuel pump may need to be commanded ON a few times in order to obtain the highest possible fuel pressure.

IMPORTANT
The fuel pressure will decrease when the fuel pump stops operating. After the fuel pump stops operating, the fuel pressure should stabilize and remain constant.

Fuel System Diagnosis

The control module enables the appropriate fuel injector pulse for each cylinder. Ignition voltage is supplied directly to the fuel injectors. The control module controls each fuel injector by grounding the control circuit via a solid state device called a driver. A fuel injector coil winding resistance that is too high or too low will affect engine driveability. A fuel injector control circuit DTC may not set, but a misfire may be apparent. The fuel injector coil windings are affected by temperature. The resistance of the fuel injector coil windings will increase as the temperature of the fuel injector increases.

Excessive resistance in the fuel injector ignition 1 voltage circuit or the fuel injector control circuit may cause the following symptoms: Lean condition Misfire Rough idle
Monitoring the misfire current counters, or misfire graph, may help isolate the fuel injector that is causing the condition.
Operating the vehicle over a wide temperature range may help isolate the fuel injector that is causing the condition.
Perform the fuel injector coil test within the conditions of the customer concern. A fuel injector condition may only be apparent at a certain temperature, or under certain conditions.

Step	Action	Values	Yes	No
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Control Module Connector End Views or Engine Controls Connector End Views
1	Did you perform the Diagnostic System Check - Vehicle?		Go to Step 2	Go to Diagnostic System Check - Vehicle in Vehicle DTC Information
2	Observe the ECT sensor parameter with a scan tool. Is the ECT sensor parameter within the specified range?	10-32°C (50-90°F)	Go to Step 3	Go to Step 4
3	Remove the fuel injector sight shield. Refer to Fuel Injector Sight Shield Replacement in Engine Mechanical - 4.6L (LH2). Measure the resistance of each fuel injector with a DMM. Refer to Testing for Continuity in Wiring Systems. Do any of the fuel injectors display a resistance outside the specified range?	11-14 ohms	Go to Step 6	Go to Diagnostic Aids
4	Remove the fuel injector sight shield. Refer to Fuel Injector Sight Shield Replacement in Engine Mechanical - 4.6L (LH2). Measure the resistance of each fuel injector with a DMM. Refer to Testing for Continuity in Wiring Systems. Record each fuel injector value. Subtract the lowest resistance value from the highest resistance value. Is the difference equal to, or less than, the specified value?	3 ohms	Go to Fuel Injector Balance Test with Special Tool	Go to Step 5
5	Add all of the fuel injector resistance values, to obtain a total resistance value. Divide the total resistance value by the number of fuel injectors, to obtain an average resistance value. Subtract the lowest individual fuel injector resistance value from the average resistance value. Compute the difference between the highest individual fuel injector resistance value and the average resistance value. Replace the fuel injector that displays the greatest resistance difference, above or below the average. Refer to Fuel Injector Replacement . Did you complete the replacement?		Go to Step 8
6	Test for an intermittent and for a poor connection at the fuel injectors. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition?		Go to Step 8	Go to Step 7
7	Replace the fuel injector or fuel injectors that are out of the specified range. Refer to Fuel Injector Replacement . Did you complete the replacement?	11-14 ohms	Go to Step 8
8	Operate the system in order to verify the repair. Did you correct the condition?		System OK	Go to Diagnostic Aids

Fuel Injector Solenoid Coil Test

The scan tool is first used to energize the fuel pump. The fuel injector tester is then used to pulse each injector for a precise amount of time, allowing a measured amount of fuel into the manifold. This causes a drop in system fuel pressure that can be recorded and used to compare each injector.

Cylinder	1	2	3	4
1st Reading	380 kPa (55 psi)	380 kPa (55 psi)	380 kPa (55 psi)	380 kPa (55 psi)
2nd Reading	215 kPa (31 psi)	201 kPa (29 psi)	208 kPa (30 psi)	229 kPa (33 psi)
Amount of Drop	165 kPa (24 psi)	179 kPa (26 psi)	172 kPa (25 psi)	151 kPa (22 psi)
Average Range: 156-176 kPa (22.5-25.5 psi)	Injector OK	Replace fuel injector - too much fuel pressure drop	Injector OK	Replace fuel injector - too little fuel pressure drop

Fuel Injector Balance Test Example (Typical)

Step	Action	Values	Yes	No
1	Did you perform the Diagnostic System Check- Vehicle?		Go to Step 2	Go to Diagnostic System Check - Vehicle in Vehicle DTC Information
2	Did you perform the Fuel Injector Coil Test?		Go to Step 3	Go to Fuel Injector Solenoid Coil Test
3	IMPORTANT: DO NOT perform this test if the ECT is above 94°C (201°F). IMPORTANT: Verify that adequate fuel is in the fuel tank before proceeding with this diagnostic. Install the fuel pressure gage. Refer to Fuel Pressure Gage Installation and Removal . Turn ON the ignition, with the engine OFF. IMPORTANT: The fuel pump may need to be commanded ON a few times, in order to obtain the highest possible fuel pressure. Command the fuel pump ON with a scan tool. Observe the fuel pressure gage, with the fuel pump operating. Is the fuel pressure within the specified range?	380-427 kPa (55-62 psi)	Go to Step 4	Go to Fuel System Diagnosis
4	IMPORTANT: The fuel pressure will decrease when the fuel pump stops operating. After the fuel pump stops operating, the fuel pressure should stabilize and remain constant. Monitor the fuel pressure gage for 5 minutes.Does the fuel pressure decrease to less than the specified value?	350 kPa (51 psi)	Go to Fuel System Diagnosis	Go to Step 5
5	NOTE: Do Not repeat any portion of this test before running the engine in order to prevent the engine from flooding. Connect the J 39021 Fuel Injector Tester to a fuel injector using the J 44602 Injector Test Adapter. Set the amperage supply selector switch on the fuel injector tester to the Balance Test 0.5-2.5 amp position. Command the fuel pump ON and OFF with a scan tool. Record the fuel pressure indicated by the fuel pressure gage after the fuel pressure stabilizes. This is the first pressure reading. IMPORTANT: Record the fuel pressure value immediately after the fuel injector stops pulsing. The fuel pressure may rise after the fuel injector stops pulsing. Do not record the higher fuel pressure value. Energize the fuel injector by depressing the Push to Start Test button on the fuel injector tester. Record the fuel pressure indicated by the fuel pressure gage after the fuel injector has stopped pulsing. This is the second fuel pressure reading. Repeat steps 1 through 6 for each fuel injector. Subtract the second pressure reading from the first pressure reading for one fuel injector. The result is the pressure drop value. Obtain a pressure drop value for each fuel injector. Add all of the individual pressure drop values. This is the total pressure drop. Divide the total pressure drop by the number of fuel injectors. This is the average pressure drop. Is the difference between any individual pressure drop and the average pressure drop more than the specified value?	10 kPa (1.5 psi)	Go to Step 6	Go to Symptoms - Engine Controls
6	Replace the affected fuel injector. Refer to Fuel Injector Replacement . Did you complete the replacement?		Go to Step 7
7	Operate the system in order to verify the repair. Did you correct the condition?		System OK	Go to Symptoms - Engine Controls

IMPORTANT
DO NOT perform this test if the ECT is above 94°C (201°F).

IMPORTANT
Verify that adequate fuel is in the fuel tank before proceeding with this diagnostic.

IMPORTANT
The fuel pump may need to be commanded ON a few times, in order to obtain the highest possible fuel pressure.

IMPORTANT
The fuel pressure will decrease when the fuel pump stops operating. After the fuel pump stops operating, the fuel pressure should stabilize and remain constant.

NOTE
Do Not repeat any portion of this test before running the engine in order to prevent the engine from flooding.

IMPORTANT
Record the fuel pressure value immediately after the fuel injector stops pulsing. The fuel pressure may rise after the fuel injector stops pulsing. Do not record the higher fuel pressure value.

Fuel Injector Balance Test with Special Tool

The engine control module (ECM) enables the appropriate fuel injector pulse for each cylinder. Ignition voltage is supplied to the fuel injectors. The ECM controls each fuel injector by grounding the control circuit via a solid state device called a driver.

The ODD INJ fuse and the EVEN INJ fuse supplies power to the fuel injectors and the ignition coil/modules. If the ODD INJ fuse is open or the EVEN INJ fuse is open and a short to ground cannot be located, refer to «Electronic Ignition (EI) System Diagnosis»(/cadillac/xlr/i-2003-2009/remont/testing-diagnostics/#engine-controls-46l-lh2-troubleshooting) .
Performing the Fuel Injector Coil Test may help isolate an intermittent condition. Refer to «Fuel Injector Solenoid Coil Test»(/cadillac/xlr/i-2003-2009/remont/testing-diagnostics/#engine-controls-46l-lh2-troubleshooting) .
If the condition is intermittent, refer to «Intermittent Conditions»(/cadillac/xlr/i-2003-2009/remont/testing-diagnostics/#engine-controls-46l-lh2-troubleshooting__intermittent-conditions) .

Step	Action	Yes	No
Schematic Reference: Engine Controls Schematics Connect End View Reference: Engine Controls Connector End Views or Engine Control Module Connector End Views
1	Did you perform the Diagnostic System Check-Vehicle?	Go to Step 2	Go to Diagnostic System Check - Vehicle in Vehicle DTC Information
2	Is DTC P0201, P0202, P0203, P0204, P0205, P0206, P0207, P0208, P0261, P0262, P0264, P0265, P0267, P0268, P0270, P0271, P0273, P0274, P0276, P0277, P0279, P0280, P0282, or P0283 set?	Go to DTC P0201, P0202, P0203, P0204, P0205, P0206, P0207, or P0208 or DTC P0261, P0264, P0267, P0270, P0273, P0276, P0279, or P0282 or DTC P0262, P0265, P0268, P0271, P0274, P0277, P0280, or P0283	Go to Step 3
3	Turn OFF the ignition. Remove the fuel injector sight shield. Refer to Fuel Injector Sight Shield Replacement in Engine Mechanical - 4.6L (LH2). Disconnect the fuel injectors for the fuse that is open. Disconnect the ignition coils/modules for the fuse that is open. Probe the ignition 1 voltage circuit of a fuel injector with a test lamp that is connected to battery voltage. Refer to Probing Electrical Connectors in Wiring Systems. Does the test lamp illuminate?	Go to Step 4	Go to Diagnostic Aids
4	Repair the short to ground in the ignition 1 voltage circuit of the fuel injectors. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair?	Go to Step 5
5	Operate the system in order to verify the repair. Did you correct the condition?	System OK	Go to Step 2

Fuel Injector Circuit Diagnosis

Water contamination in the fuel system may cause driveability conditions such as hesitation, stalling, no start, or misfires in one or more cylinders. Water may collect near a single fuel injector at the lowest point in the fuel injection system, and cause a misfire in that cylinder. If the fuel system is contaminated with water, inspect the fuel system components for rust, or deterioration.

Alcohol concentrations of 10 percent or greater in fuel can be detrimental to fuel system components. Alcohol contamination may cause fuel system corrosion, deterioration of rubber components, and subsequent fuel filter restriction. Some types of alcohol are more detrimental to fuel system components than others. Ethanol is commonly used in gasoline, but in concentrations of no more than 10 percent. Some fuels, such as E85, contain a very high percentage of ethanol. Fuel with more than 10 percent ethanol may cause driveability conditions such as hesitation, lack of power, stalling, or no start.

Alcohol in Fuel Testing Procedure

The fuel sample should be drawn from the bottom of the tank so that any water present in the tank will be detected. The sample should be bright and clear. If alcohol contamination is suspected then use the following procedure to test the fuel quality.

Using a 100 ml (3.4 oz) specified cylinder with 1 ml (0.03 oz) graduation marks, fill the cylinder with fuel to the 90 ml (3.04 oz) mark.
Add 10 ml (0.34 oz) of water in order to bring the total fluid volume to 100 ml (3.4 oz) and install a stopper.
Shake the cylinder vigorously for 10-15 seconds.
Carefully loosen the stopper in order to release the pressure.
Re-install the stopper and shake the cylinder vigorously again for 10-15 seconds.
Put the cylinder on a level surface for approximately 5 minutes in order to allow adequate liquid separation.

If alcohol is present in the fuel, the volume of the lower layer, which would now contain both alcohol and water, will be more than 10 ml (0.34 oz). For example, if the volume of the lower layer is increased to 15 ml (0.51 oz), this indicates at least 5 percent alcohol in the fuel. The actual amount of alcohol may be somewhat more because this procedure does not extract all of the alcohol from the fuel.

Particulate Contaminants in Fuel Testing Procedure

The fuel sample should be drawn from the bottom of the tank so that any water present in the tank will be detected. The sample should be bright and clear. If the sample appears cloudy, or contaminated with water, as indicated by a water layer at the bottom of the sample, use the following procedure to diagnose the fuel.

Using an approved fuel container, draw approximately 0.5 liter (0.13 gal) of fuel.
Place the cylinder on a level surface for approximately 5 minutes in order to allow settling of the particulate contamination.

Particulate contamination will show up in various shapes and colors. Sand will typically be identified by a white or light brown crystals. Rubber will appear as black and irregular particles. If particles are found clean the entire fuel system thoroughly. Refer to Fuel System Cleaning .

Ethanol concentrations of greater than 10 percent can cause driveability conditions and fuel system deterioration. Fuel with more than 10 percent ethanol could result in driveability conditions such as hesitation, lack of power, stalling, or no start. Excessive concentrations of ethanol used in vehicles not designed for it may cause fuel system corrosion, deterioration of rubber components, and fuel filter restriction.

Test Procedure

Test the fuel composition using J 44175 Fuel Composition Tester and J44175-3 Instruction Manual.
If water appears in the fuel sample, clean the fuel system. Refer to «Fuel System Cleaning»(/cadillac/xlr/i-2003-2009/remont/testing-diagnostics/#engine-controls-46l-lh2-introduction-2-of-2__fuel-system-cleaning) .
Subtract 50 from the reading on the DMM in order to obtain the percentage of alcohol in the fuel sample. Refer to the examples in the Fuel Composition Test Examples table.
If the fuel sample contains more than 15 percent ethanol, add fresh, regular gasoline to the vehicle's fuel tank.
Test the fuel composition.
If testing shows the ethanol percentage is still more than 15 percent, replace the fuel in the vehicle. Refer to «Fuel System Cleaning»(/cadillac/xlr/i-2003-2009/remont/testing-diagnostics/#engine-controls-46l-lh2-introduction-2-of-2__fuel-system-cleaning) .

	Frequency (Hz)	Subtract 50	Ethanol Percent
Example A	50 Hz	50	0
Example B	65 Hz	50	15
Example C	129 Hz	50	79

Fuel Composition Test Examples

The ignition system utilizes an individual module/coil for each spark plug. The following 4 circuits support each ignition module/coil assembly.

The ignition 1 voltage circuit
The ground circuit
Ignition control (IC) circuit
Low reference circuit

Each ignition module/coil connects directly to its spark plug through a wire spring conductor internal to the spark plug boot. The IC circuits transmits timing pulses from the engine control module (ECM) to each ignition module/coil assembles in the proper sequence for the spark plug firing event. The ECM monitors each IC circuit for improper voltage levels. If an improper voltage level is detected on an IC circuit a DTC will set.

This Electronic Ignition (EI) System Diagnostic table assumes that the battery is fully charged. Refer to «Battery Inspection/Test»(/cadillac/xlr/i-2003-2009/remont/charging-system/#battery-charging-system-and-starting-system) in Engine Electrical.
Other electrical, fuel, or mechanical conditions can cause an engine to crank but does not run, or set a DTC P0300 misfire code.
An ignition coil, boots, or spark plugs may misfire only when moisture is present. Although difficult to test on this engine, selectively wetting down parts of the ignition system and monitoring for a misfire may help in isolating an intermittent condition. Replace any worn or torn spark plug boots or seals.
If the ODD INJ or EVEN INJ fuse opens, this will also result in the loss of ignition 1 voltage to the odd or even fuel injectors.

Step	Action	Values	Yes	No
Schematic Reference: Engine Controls Schematics Connector End View Reference: Engine Control Module Connector End Views or Engine Controls Connector End Views
1	Did you perform the Diagnostic System Check - Vehicle?		Go to Step 2	Go to Diagnostic System Check - Vehicle in Vehicle DTC Information
2	Attempt to start the engine. Does the engine start and run?		Go to Step 37	Go to Step 3
3	Turn OFF the ignition. Remove the underhood fuse block cover. Probe both test points of the EVEN INJ fuse with a test lamp that is connected to a good ground. Refer to Troubleshooting with a Test Lamp in Wiring Systems. Does the test lamp illuminate on either test point of the fuse?		Go to Step 9	Go to Step 4
4	Turn OFF the ignition. Probe both test points of the ODD INJ fuse with a test lamp that is connected to a good ground. Does the test lamp illuminate on either test point of the fuse?		Go to Step 10	Go to Step 5
5	Turn ON the ignition, with the engine OFF. Probe both test points of the EVEN INJ fuse with a test lamp that is connected to a good ground. Does the test lamp illuminate on both test points of the fuse?		Go to Step 7	Go to Step 6
6	Does the test lamp illuminate on one test point of the fuse?		Go to Step 11	Go to Ignition 1 Relay Diagnosis
7	Turn ON the ignition. Probe both test points of the ODD INJ fuse with a test lamp that is connected to a good ground. Does the test lamp illuminate on both test points of the fuse?		Go to Step 19	Go to Step 8
8	Does the test lamp illuminate on one test point of the fuse?		Go to Step 15	Go to Ignition 1 Relay Diagnosis
9	Turn OFF the ignition. Disconnect the 7-way electrical connector at the bank 2 ignition coil bracket. Disconnect the negative battery cable at the battery. Refer to Battery Negative Cable Disconnection and Connection in Engine Electrical. Disconnect the underhood fuse block electrical connector that contains the ignition 1 voltage circuit for the bank 2 coils. Connect the negative battery cable at the battery. Probe the ignition 1 voltage circuit for the bank 2 ignition coils at the underhood fuse block electrical connector with a test lamp that is connected to a good ground. Refer to Probing Electrical Connectors in Wiring Systems. Does the test lamp illuminate?		Go to Step 55	Go to Step 64
10	Turn OFF the ignition. Disconnect the 7-way electrical connector at the bank 1 ignition coil bracket. Disconnect the negative battery cable at the battery. Refer to Battery Negative Cable Disconnection and Connection in Engine Electrical. Disconnect the underhood fuse block electrical connector that contains the ignition 1 voltage circuit for the bank 1 coils. Connect the negative battery cable at the battery. Probe the ignition 1 voltage circuit for the bank 1 ignition coils at the underhood fuse block electrical connector with a test lamp that is connected to a good ground. Refer to Probing Electrical Connectors in Wiring Systems. Does the test lamp illuminate?		Go to Step 55	Go to Step 64
11	Turn OFF the ignition. Replace the EVEN INJ fuse. Disconnect the 7-way electrical connector at the bank 2 ignition module/coil bracket. Monitor the EVEN INJ fuse. Turn ON the ignition, with the engine OFF. Does the EVEN INJ fuse open?		Go to Step 12	Go to Step 13
12	Turn OFF the ignition. Disconnect the negative battery cable. Refer to Battery Negative Cable Disconnection and Connection in Engine Electrical. Disconnect the underhood fuse block electrical connector that contains the ignition 1 voltage circuit to the bank 2 ignition coils. Connect the negative cable at the battery. Replace the EVEN INJ fuse. Monitor the EVEN INJ fuse. Turn ON the ignition, with the engine OFF. Does the EVEN INJ fuse open?		Go to Step 64	Go to Step 56
13	Turn OFF the ignition. Connect the 7-way bank 2 ignition module/coil electrical connector. Disconnect the electrical connectors at the bank 2 ignition module/coil assemblies. Monitor the EVEN INJ fuse. Turn ON the ignition, with the engine OFF. Does the EVEN INJ fuse open?		Go to Step 57	Go to Step 14
14	Turn ON the ignition, with the engine OFF. Monitor the EVEN INJ fuse. Connect one bank 2 ignition module/coil electrical connector at a time. Does the EVEN INJ fuse open while connecting a ignition module/coil connector?		Go to Step 65	Go to Intermittent Conditions
15	Turn OFF the ignition. Replace the ODD INJ fuse. Disconnect the 7-way electrical connector at the bank 1 ignition module/coil bracket. Monitor the ODD INJ fuse. Turn ON the ignition, with the engine OFF. Does the ODD INJ fuse open?		Go to Step 16	Go to Step 17
16	Turn OFF the ignition. Disconnect the negative battery cable. Refer to Battery Negative Cable Disconnection and Connection in Engine Electrical. Disconnect the underhood fuse block electrical connector that contains the ignition 1 voltage circuit to the bank 1 ignition coils. Connect the negative cable at the battery. Replace the ODD INJ fuse. Monitor the ODD INJ fuse. Turn ON the ignition, with the engine OFF. Does the ODD INJ fuse open?		Go to Step 64	Go to Step 56
17	Turn OFF the ignition. Connect the 7-way bank 1 ignition module/coil electrical connector. Disconnect the electrical connectors at the bank 1 ignition module/coil assemblies. Monitor the ODD INJ fuse. Turn ON the ignition, with the engine OFF. Does the ODD INJ fuse open?		Go to Step 57	Go to Step 18
18	Turn ON the ignition, with the engine OFF. Monitor the ODD INJ fuse. Connect one bank 1 ignition module/coil electrical connector at a time. Does the ODD INJ fuse open while connecting a ignition module/coil connector?		Go to Step 65	Go to Intermittent Conditions
19	Turn ON the ignition, with the engine OFF. Disconnect the bank 2 electrical connectors at the ignition module/coils. Probe the ignition 1 voltage circuit for each ignition module/coil with a test lamp that is connected to a good ground. Refer to Troubleshooting with a Test Lamp or Probing Electrical Connectors in Wiring Systems. Does the test lamp illuminate at each ignition module/coil connector?		Go to Step 20	Go to Step 21
20	Turn OFF the ignition. Remove the EVEN INJ fuse from the underhood fuse block. Measure the resistance of the ignition 1 voltage circuit from the underhood fuse block to each ignition module/coil on bank 2 with a DMM. Refer to Troubleshooting with a Digital Multimeter in Wiring Systems. Does the resistance measure greater than the specified value to each ignition module/coil?	2 ohms	Go to Step 23	Go to Step 25
21	Turn ON the ignition with the engine OFF. Disconnect the 7-way electrical connector for the ignition module/coils on bank 2. Probe the ignition 1 voltage circuit that leads from the underhood fuse block, to the 7-way electrical connector with a test lamp that is connected to a good ground. Does the test lamp illuminate?		Go to Step 58	Go to Step 22
22	Turn OFF the ignition. Disconnect the negative battery cable at the battery. Refer to Battery Negative Cable Disconnection and Connection . Disconnect the underhood fuse block electrical connector that contains the ignition 1 voltage circuit for the bank 2 ignition module/coils. Connect the negative battery cable at the battery. Connect a 20-amp fused jumper wire from the battery positive voltage to the ignition 1 voltage circuit terminal at the underhood fuse block electrical connector. Refer to Using Fused Jumper Wires in Wiring Systems. Probe the ignition 1 voltage circuit at the 7-way bank 2 electrical connector that leads from the underhood fuse block, with a test lamp that is connected to a good ground. Does the test lamp illuminate?		Go to Step 24	Go to Step 59
23	Turn OFF the ignition. Disconnect the negative battery cable at the battery. Refer to Battery Negative Cable Disconnection and Connection in Engine Electrical. Disconnect the underhood fuse block electrical connector that contains the ignition 1 voltage circuit for the bank 2 ignition module/coils. Measure the resistance of the ignition 1 voltage circuit from the underhood fuse block electrical connector to each ignition module/coil on bank 2 with a DMM. Does the resistance measure greater than the specified value to each ignition module/coil?	2 ohms	Go to Step 60	Go to Step 24
24	Measure the resistance of the underhood fuse block ignition 1 voltage circuit for the bank 2 ignition module/coil with a DMM. Refer to Troubleshooting with a Digital Multimeter in Wiring Systems. Does the resistance measure more than the specified value?	2 ohms	Go to Step 64	Go to Intermittent Conditions
25	Turn ON the ignition, with the engine OFF. Disconnect the bank 1 electrical connectors at the ignition module/coils. Probe the ignition 1 voltage circuit for each ignition module/coil with a test lamp that is connected to a good ground. Does the test lamp illuminate at each ignition module/coil connector?		Go to Step 26	Go to Step 27
26	Turn OFF the ignition. Remove the ODD INJ fuse from the underhood fuse block. Measure the resistance of the ignition 1 voltage circuit from the underhood fuse block to each ignition module/coil on bank 1 with a DMM. Refer to Troubleshooting with a Digital Multimeter in Wiring Systems. Does the resistance measure greater than the specified value to each ignition module/coil?	2 ohms	Go to Step 29	Go to Step 31
27	Turn ON the ignition, with the engine OFF. Disconnect the 7-way bank 1 ignition module/coil electrical connector. Probe the ignition 1 voltage circuit that leads from the underhood fuse block to the 7-way connector with a test lamp that is connected to a good ground. Does the test lamp illuminate?		Go to Step 58	Go to Step 28
28	Turn OFF the ignition. Disconnect the negative battery cable at the battery. Refer to Battery Negative Cable Disconnection and Connection . Disconnect the underhood fuse block electrical connector that contains the ignition 1 voltage circuit for the bank 1 ignition module/coils. Connect the negative battery cable at the battery. Connect a 20-amp fused jumper wire from battery positive voltage to the ignition 1 voltage circuit at the underhood fuse block. Refer to Using Fused Jumper Wires in Wiring Systems. Probe the ignition 1 voltage circuit at the 7-way bank 1 electrical connector that leads from the underhood fuse block, with a test lamp that is connected to a good ground. Does the test lamp illuminate?		Go to Step 30	Go to Step 59
29	Turn OFF the ignition. Disconnect the negative battery cable at the battery. Refer to Battery Negative Cable Disconnection and Connection in Engine Electrical. Disconnect the underhood fuse block electrical connector that contains the ignition 1 voltage circuit for the bank 1 ignition module/coils. Measure the resistance of the ignition 1 voltage circuit from the underhood fuse block electrical connector to each ignition module/coil on bank 1 with a DMM. Does the resistance measure greater than the specified value to each ignition module/coil?	2 ohms	Go to Step 60	Go to Step 30
30	Measure the resistance of the underhood fuse block ignition 1 voltage circuit for the bank 1 ignition module/coil with a DMM. Refer to Troubleshooting with a Digital Multimeter in Wiring Systems. Does the resistance measure greater than the specified value?	2 ohms	Go to Step 64	Go to Intermittent Conditions
31	Turn OFF the ignition. Disconnect the electrical connectors at the bank 2 ignition module/coils assembly. Probe the ground circuit for each bank 2 ignition module/coil with a test lamp that is connected to battery positive voltage. Does the test lamp illuminate?		Go to Step 32	Go to Step 61
32	Measure the resistance of the ground circuit from each ignition module/coil electrical connector on bank 2 to a good engine ground with a DMM. Refer to Troubleshooting with a Digital Multimeter in Wiring Systems. Does the resistance measure greater than the specified value from each ignition module/coil electrical connector?	2 ohms	Go to Step 61	Go to Step 33
33	Turn OFF the ignition. Disconnect the electrical connectors at the bank 1 ignition module/coils assembly. Probe the ground circuit at each bank 1 ignition module/coil electrical connector with a test lamp that is connected to battery positive voltage. Does the test lamp illuminate?		Go to Step 34	Go to Step 61
34	Measure the resistance of the ground circuit from each ignition module/coil electrical connector on bank 1 to a good engine ground with a DMM. Does the resistance measure greater than the specified value from each ignition module/coil?	2 ohms	Go to Step 61	Go to Step 35
35	Turn OFF the ignition. Disconnect the bank 2 electrical connector at each of the ignition module/coils. Disconnect the electrical connector at the engine control module (ECM) that contains the low reference circuit for bank 2. Measure the resistance of the EST low reference circuit from each ignition module/coil to the ECM with a DMM. Refer to Troubleshooting with a Test Lamp in Wiring Systems. Does the resistance measure greater than the specified value?	2 ohms	Go to Step 62	Go to Step 36
36	Disconnect the bank 1 electrical connector at each ignition module/coil. Measure the resistance of the EST low reference circuit from each ignition module/coil to the ECM with a DMM. Does the resistance measure greater than the specified value?	2 ohms	Go to Step 62	Go to Step 67
37	Observe the misfire current counters with a scan tool. Does a cylinder indicate an increasing misfire count?		Go to Step 38	Go to Intermittent Conditions
38	Turn ON the ignition, with the engine OFF. Remove the underhood fuse block cover. Probe both test points of the fuse for the bank of cylinders that are identified as misfiring with a test lamp that is connected to a good ground. Refer to Troubleshooting with a Test Lamp in Wiring Systems. Does the test lamp illuminate on both test points of the fuse?		Go to Step 44	Go to Step 39
39	Does the test lamp illuminate on one test point of the fuse?		Go to Step 40	Go to Ignition 1 Relay Diagnosis
40	Turn OFF the ignition. Replace the open fuse for the bank of cylinders identified as misfiring. Disconnect the 7-way electrical connector for the bank of cylinders identified as misfiring at the ignition module/coil bracket. Turn ON the ignition with the engine OFF. Does the fuse open?		Go to Step 41	Go to Step 42
41	Turn OFF the ignition. Disconnect the negative battery cable at the battery. Refer to Battery Negative Cable Disconnection and Connection in Engine Electrical. Disconnect the underhood fuse block electrical connector that contains the ignition 1 voltage circuit to the bank of cylinders identified as misfiring. Replace the open fuse. Connect the negative battery cable at the battery. Turn ON the ignition, with the engine OFF. Does the fuse open?		Go to Step 64	Go to Step 56
42	Turn OFF the ignition. Connect the 7-way electrical connector at the ignition module/coil bracket. Disconnect the electrical connectors at the ignition module/coil assemblies on the bank of cylinders identified as misfiring. Turn ON the ignition with the engine OFF. Does the fuse open?		Go to Step 57	Go to Step 43
43	Turn ON the ignition, with the engine OFF. Monitor the fuse for the bank of cylinders identified as misfiring. Connect each ignition module coil electrical connector one at a time. Does the fuse open while connecting an ignition module/coil connector?		Go to Step 65	Go to Intermittent Conditions
44	Turn OFF the ignition. Disconnect the negative battery cable at the battery. Refer to Battery Negative Cable Disconnection and Connection in Engine Electrical. Disconnect the underhood fuse block electrical connector that contains the ignition 1 voltage circuit for the affected cylinder. Measure the resistance of the ignition 1 voltage circuit from the underhood fuse block electrical connector to the affected ignition module/coil with a DMM. Refer to Circuit Testing in Wiring Systems. Does the resistance measure greater than the specified value?	2 ohms	Go to Step 60	Go to Step 45
45	Measure the resistance of the ignition 1 voltage bus bar circuit of the underhood fuse block for a high resistance or an open, with a DMM. Does the resistance measure greater than the specified value?	2 ohms	Go to Step 64	Go to Step 46
46	Measure the resistance of the ground circuit from the ignition module/coil electrical connector of the affected cylinder to a good ground with a DMM. Does the resistance measure greater than the specified value?	2 ohms	Go to Step 61	Go to Step 47
47	Disconnect the ECM electrical connector that contains the ignition coil control circuit for the affected cylinder. Measure the resistance of the ignition coil control circuit between the ignition module/coil electrical connector of the affected cylinder and the ECM electrical connector. Does the resistance measure more than the specified value?	2 ohms	Go to Step 63	Go to Step 48
48	Disconnect the ECM electrical connectors. Measure the resistance of the low reference circuit from the ignition module/coil electrical connector to the ECM electrical connector with a DMM. Does the resistance measure greater than the specified value?	2 ohms	Go to Step 62	Go to Step 49
49	Turn OFF the ignition. Disconnect the ignition module/coil assembly from the spark plugs on the bank of cylinders which indicated a misfire condition. Inspect the ignition module/coil assembly for the following: Any visible cracks, deterioration or other damage. Any carbon tracking or other signs of arcing. Any missing or damage spark plug boot springs. Replace the component if the inspection reveals a condition. Did you find a condition?		Go to Step 67	Go to Step 50
50	Remove the spark plug for the cylinder that was identified as causing a misfire. Refer to Spark Plug Replacement . Does the spark plug indicate oil contamination?		Go to Base Engine Misfire with Excessive Oil Consumption in Engine Mechanical	Go to Step 51
51	Does the spark plug indicate coolant contamination?		Go to Base Engine Misfire with Coolant Consumption in Engine Mechanical	Go to Step 52
52	Exchange the suspected spark plug with a spark plug from a different cylinder on the same bank. Refer to Spark Plug Replacement . Reinstall the ignition module/coil assembly. Monitor the misfire current counters with a scan tool. Start the engine. Does the misfire move with the spark plug exchange?		Go to Step 66	Go to Step 53
53	Turn OFF the ignition. Exchange the ignition module/coil on the cylinder identified as misfiring with a ignition module/coil assembly from a different cylinder on the same bank. Monitor the misfire current counters with a scan tool. Start the engine. Does the misfire move with the ignition module/coil exchange?		Go to Step 65	Go to Step 54
54	Test for an intermittent and for a poor connection at the ignition module/coil electrical connector. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition?		Go to Step 67	Go to Base Engine Misfire without Internal Engine Noises in Engine Mechanical
55	Repair the short to battery positive voltage in the ignition 1 voltage circuit. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair?		Go to Step 67
56	Repair the short to ground in the ignition 1 voltage circuit between the underhood junction block and the 7-way electrical connector. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair?		Go to Step 67
57	Repair the short to ground in the ignition 1 voltage circuit between the 7-way electrical connector and the ignition module/coils. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair?		Go to Step 67
58	Repair the high resistance or an open in the ignition 1 voltage circuit between the 7-way electrical connector and the ignition module/coils. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair?		Go to Step 67
59	Repair the high resistance or an open in the ignition 1 voltage circuit between the underhood fuse block electrical connector and the 7-way electrical connector. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair?		Go to Step 67
60	Repair the high resistance or an open in the ignition 1 voltage circuit between the underhood fuse block electrical connector and the ignition module/coil electrical connectors. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair?		Go to Step 67
61	Repair the high resistance or an open in the ground circuit for the ignition module/coil assembly. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair?		Go to Step 67
62	Repair the high resistance or an open in the low reference circuit for the ignition module/coil assembly. Refer to Wiring Repairs in Wiring Systems. Did you complete the repair?		Go to Step 67
63	Repair the high resistance in the ignition coil control circuit. Did you complete the repair?		Go to Step 67
64	Replace the underhood fuse block. Refer to Underhood Electrical Center or Junction Block Replacement in Wiring Systems. Did you complete the replacement?		Go to Step 67
65	Replace the ignition module/coil assembly. Refer to Ignition Coil Replacement - Bank 1 or Ignition Coil Replacement - Bank 2 . Did you complete the replacement?		Go to Step 67
66	Replace the spark plug. Refer to Spark Plug Replacement . Did you complete the replacement?		Go to Step 67
67	Were you sent to this diagnostic table from the Engine Cranks but Does Not Run diagnostic table?		Go to Step 69	Go to Step 68
68	Were you sent to this diagnostic table from DTC P0300 diagnostic table?		Go to Step 70
69	Replace any open fuses. Attempt to start the engine. Does the engine start and run?		Go to Step 71	Go to Engine Cranks but Does Not Run
70	Replace any open fuses. Clear the DTCs with a scan tool. Turn OFF the ignition for 30 seconds. Operate the vehicle within the conditions for running the DTC P0300. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records. Did the DTC fail this ignition?		Go to DTC P0300	Go to Step 71
71	Observe the Capture Info with a scan tool. Are there any DTCs that have not been diagnosed?		Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information	System OK

Electronic Ignition (EI) System Diagnosis

Several states require that a vehicle pass on-board diagnostic (OBD) system tests and the I/M emission inspection in order to renew license plates. This is accomplished by viewing the I/M System Status display on a scan tool. Using a scan tool, the technician can observe the I/M System Status in order to verify that the vehicle meets the criteria that comply with the local area requirements.

Conditions for Updating the I/M System Status

Each system monitor requires at least one, and sometimes several diagnostic tests. The result of each test is reported by a diagnostic trouble code (DTC). A system monitor is complete when either all of the DTCs comprising the monitor have Run and Passed, or when any one of the DTCs comprising the monitor has illuminated the malfunction indicator lamp (MIL). Once the system monitor is complete, the I/M System Status display will indicate YES in the Completed column.

For example, when the HO2S Heater Status indicates YES, either all of the oxygen sensor heater tests have passed or one of the tests has illuminated the MIL. If the vehicle has four heated oxygen sensors, either all four heater circuit tests have passed or one of the heater circuit tests has illuminated the MIL. The I/M System Status will indicate NO under the Completed column when any of the required tests for that system have not run. The following is a list of conditions that would set the I/M System Status indicator to NO

The vehicle is new from the factory and has not yet been driven through the necessary drive conditions to complete the tests.
The battery has been disconnected or discharged below operating voltage.
The control module power or ground has been interrupted.
The control module has been reprogrammed.
The control module DTCs have been cleared as part of a service procedure.

Monitored Emission Control Systems

The OBD II System monitors all emission control systems that are on-board. Not all vehicles have a full complement of emission control systems. For example, a vehicle may not be equipped with secondary air injection (AIR) or exhaust gas recirculation (EGR). The OBD II regulations require monitoring of the following

The air conditioning system
The catalytic converter efficiency
Comprehensive component monitoring-Emission related inputs and outputs
The evaporative emissions (EVAP) system
The EGR System
The fuel delivery system
Heated catalyst monitoring
Misfire monitoring
The oxygen sensor system (O2S or HO2S)
The oxygen sensor heater system (HO2S heater)
The AIR system

For the specific DTCs required for each system, refer to Inspection/Maintenance (I/M) System DTC Table . Systems such as fuel delivery, misfire, and comprehensive components may not be listed in a system status list. These tests run continuously and do not require an I/M System Status indicator.

Step	Action	Yes	No
1	Perform Diagnostic System Check - Vehicle . IMPORTANT: Many DTC related repairs will instruct the technician to clear the DTC information. This procedure will reset ALL of the I/M System Status indicators to NO, and require performing the I/M Complete System Set Procedure. Repair any DTCs or driveability concerns that would prevent the I/M System Status tests from completing. Did you find and repair a DTC or driveability concern?	Go to Step 3	Go to Step 2
2	Review any service bulletins for software updates that may prevent I/M readiness. Perform any reprogramming or repairs indicated by the service bulletins. Was a reprogramming or repair service required?	Go to Inspection/Maintenance (I/M) Complete System Set Procedure	Go to Step 3
3	Observe the I/M System Status display with a scan tool. Is more than one test indicating a NO status?	Go to Inspection/Maintenance (I/M) Complete System Set Procedure	Go to the I/M System Set Procedure for the indicated system

IMPORTANT
Many DTC related repairs will instruct the technician to clear the DTC information. This procedure will reset ALL of the I/M System Status indicators to NO, and require performing the I/M Complete System Set Procedure.

Inspection/Maintenance (I/M) System Check

The purpose of the Inspection/Maintenance (I/M) Complete System Set Procedure is to satisfy the enable criteria necessary to execute all of the I/M readiness diagnostics, and complete the trips for those particular diagnostics. When all diagnostic tests are completed, the I/M System Status indicators are set to YES. Perform this test when more than one or all of the I/M System Status indicators are set to NO.

Conditions for Running

The barometric pressure (BARO) is more than 74 kPa.
The start-up intake air temperature is between 4-32°C (39-90°F).
The difference between the start-up engine coolant temperature (ECT) and the start-up intake air temperature (IAT) is less than 4.5°C (8°F).
The battery voltage is more than 10.5 volts.
The fuel level is between 15-85 percent.

Rough road conditions may prevent some of the tests from running. Extreme high or low ambient temperatures may prevent tests such as heated oxygen sensor (HO2S) heater and evaporative emission (EVAP) system from initiating. If a step is interrupted before completion, perform the remaining portion of the set procedures. Any portion of the set procedure that requires the engine at operating temperature may be repeated. This allows most of the diagnostics to run and the remaining tests can be performed using the individual System Set Procedures.

The scan tool can be used to monitor each of the I/M System Status indicators during the I/M Complete System Set Procedure. When all of the indicators for a test step have updated to YES, testing can move on to the next step even if the remaining portion of the test is not complete. For example, step 3 is designed to run the EVAP, secondary air injection (AIR), and HO2S tests. The procedure instructs the technician to operate the vehicle in the enable conditions for 6 minutes. If all 3 tests have updated to YES within 4 minutes, it is not necessary to continue with the enable conditions and testing can advance to the next step.

The numbers below refer to the step numbers on the diagnostic table.

2: This step runs the HO2S Heater Tests and initiate the EVAP System Test. Preprogramming the scan tool will reduce the amount of time the oxygen sensor heaters operate while verifying the enable criteria.
3: This step runs the EVAP, AIR, and the oxygen sensor (O2S) tests. The EVAP test begins once the engine coolant reaches a calibrated temperature. The AIR test, if equipped, begins shortly after Closed Loop and the indicated speed is achieved. The oxygen sensor tests begin once the engine is at operating temperature, in Closed Loop fuel control, and a calibrated amount of time has elapsed.
5: The I/M System Status only reports on whether or not a diagnostic has run, not the outcome of the test. If any emission related DTC sets after the tests are complete, the DTC will require diagnosis.

Step	Action	Value(s)	Yes	No
1	Did you perform the Inspection/Maintenance (I/M) System Check?		Go to Step 2	Go to Inspection/Maintenance (I/M) System Check
2	IMPORTANT: Whenever the ignition is turned ON, ignition positive voltage is supplied to the heated oxygen sensor (HO2S) heaters. After verifying the enable criteria, turn OFF the ignition for approximately 5 minutes to allow the sensors to cool before continuing with the test. Once the engine is started, DO NOT turn the engine OFF for the remaining portion of the set procedure. Preprogram the scan tool with the vehicle information before the ignition is turned ON. Ensure that the vehicle is within the Conditions for Running specified in the supporting text. Turn OFF all of the accessories, e.g., A/C, blower fan, etc. Set the vehicle parking brake. Verify the transmission is in Park for automatic transmissions and Neutral for manual transmissions. Start the engine and allow the engine to idle for the specified time Is the action complete?	2 minutes	Go to Step 3
3	CAUTION: Refer to Road Test Caution in Cautions and Notices. In order for the next group of tests to run, the vehicle must operate in the following conditions: Acceleration at part throttle to 90 km/h (55 mph). Continued operation under these conditions for an additional 15 minutes. Is the action complete?		Go to Step 3
4	Observe the I/M System Status display with a scan tool. Did all of the I/M System Status indicators update to YES?		Go to Step 5	Go to the I/M System Set Procedure for the indicated systems.
5	Observe the Emission Related DTC portion of the I/M System Status display with a scan tool. Does the scan tool indicate any Emission Related DTCs set?		Go to Inspection/Maintenance (I/M) System DTC Table	System OK

IMPORTANT
Whenever the ignition is turned ON, ignition positive voltage is supplied to the heated oxygen sensor (HO2S) heaters. After verifying the enable criteria, turn OFF the ignition for approximately 5 minutes to allow the sensors to cool before continuing with the test. Once the engine is started, DO NOT turn the engine OFF for the remaining portion of the set procedure.

CAUTION
Refer to Road Test Caution in Cautions and Notices.

Inspection/Maintenance (I/M) Complete System Set Procedure

Inspection/Maintenance (I/M) System DTC Table

System	DTCs Required to Set System Status to YES
Catalyst	DTC P0420 or P0430
EVAP	DTC P0442 DTC P0446 DTC P0451 DTC P0455 DTC P0496
Oxygen Sensor	DTC P0131 or P0151 DTC P0132 or P0152 DTC P0139 or P0159 DTC P0140 or P0160 DTC P0133 or P0153
Oxygen Sensor Heater	DTC P0135 or P0155 DTC P0141 or P0161

Inspection/Maintenance (I/M) System DTC Table

The purpose of this test is to satisfy the enable criteria necessary to execute inspection/maintenance (I/M) readiness diagnostics for the Catalyst System. The test may be used to set the I/M System Status indicators to YES.

The barometric pressure (BARO) is more than 74 kPa.
The engine coolant temperature (ECT) is more than 63°C (145°F).
The engine is in closed loop fuel control.

The control module runs a maximum of 12 tests per trip until the Catalyst System Status updates to YES. If the status does not update, the test outlined in this procedure can be repeated until the I/M System Status updates to YES.

If there is an impending failure, the system may require more time to run the diagnostic than was allotted in the set procedure. If the test does not run after numerous attempts and no DTC is set, review the appropriate scan tool data list and the service information for an indication of why the test does not complete. Some tests may abort due to changes in the conditions while the test is running. For example, changes in engine load such as a cooling fan or A/C compressor clutch turning ON may cause the test to abort.

Step	Action	Yes	No
1	Did you perform the Inspection/Maintenance (I/M) System Check?	Go to Step 2	Go to Inspection/Maintenance (I/M) System Check
2	Ensure that the vehicle is within the Conditions for Running specified in the supporting text. Turn OFF all of the accessories, e.g., A/C, blower fan, etc. Start and allow the engine to idle for 2 minutes. CAUTION: Refer to Road Test Caution in Cautions and Notices. Accelerate at part throttle to 90 km/h (55 mph) with this speed maintained for 10 minutes. Observe the I/M System Status display with a scan tool. Did the Catalyst System Status update to YES?	Go to Step 5	Go to Step 3
3	Observe the DTC information with a scan tool Does the scan tool indicate any failed DTCs?	Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information	Go to Step 4
4	Refer to the Inspection/Maintenance (I/M) System DTC Table to determine which DTCs are required to run in order to complete this test. Observe the Not Ran Since Code Cleared display with a scan tool. Determine which of the DTCs required for a YES status has not run. Enter the DTC number in the Specific DTC menu of the scan tool. Operate the vehicle within the Conditions for Running the DTC, located in the supporting text for the diagnostic table of the DTC. Repeat numbers 4 and 5 of this step for any additional required DTCs that have not run. Observe the I/M System Status display with a scan tool. Did the Catalyst System Status update to YES?	Go to Step 5	Go to Diagnostic Aids
5	Observe the Emission Related DTC portion of the I/M System Status display with a scan tool. Does the scan tool indicate any Emission Related DTCs set?	Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information	System OK

CAUTION
Refer to Road Test Caution in Cautions and Notices.

Inspection/Maintenance (I/M) Catalyst System Set Procedure

The purpose of this test is to satisfy the enable criteria necessary to execute the inspection/maintenance (I/M) readiness diagnostics for the Evaporative Emission (EVAP) System. The test may be used in order to set the I/M System Status indicators to YES. The I/M System Status Display on the scan tool provides an indication of when the control module has completed the required tests. The I/M System Status does not indicate that the tests have passed or failed. When all of the diagnostics for a specific system have run and passed the I/M System Status will update to YES. If a test for a specific system has failed, the I/M System Status will update to YES, indicating a determination was made, even if all of the other tests for that system have not run. If a small leak is detected, a minimum of 3 drive cycles may be required before the I/M System Status will update to YES. Performing a visual inspection prior to running the EVAP test may prevent having to repeat the test. A failed or aborted test will require the vehicle to cool down in order to meet the enable criteria to run another test.

The barometric pressure (BARO) is more than 74 kPa.
The start-up intake air temperature (IAT) is between 4-32°C (39-90°F).
The difference between the start-up engine coolant temperature (ECT) and the start-up IAT is less than 4.5°C (8°F).
The fuel level is between 15-85 percent.
The battery voltage is more than 10.5 volts.
The engine is in closed loop fuel control.

If there is an impending failure, the system may require more time to run the diagnostic than allotted in the set procedure. If the test does not run after numerous attempts and no DTC is set, review the appropriate scan tool data list and the service information for an indication of why the test does not complete. Some tests may abort due to changes in the conditions while the test is running. For example, changes in engine load such as cooling fan or an A/C compressor clutch turning ON may cause the test to abort.

Step	Action	Yes	No
1	Did you perform the Inspection/Maintenance (I/M) System Check?	Go to Step 2	Go to Inspection/Maintenance (I/M) System Check
2	Ensure the vehicle is within the Conditions for Running specified in the supporting text. Turn OFF all of the accessories, including the A/C and the blower fan. IMPORTANT: Once the engine is started, DO NOT turn the engine OFF for the remainder of the procedure until the test is complete. Start and idle the engine for 2 minutes. CAUTION: Refer to Road Test Caution in Cautions and Notices. IMPORTANT: In order for this test to run, the vehicle must operate in the following conditions: Accelerate at part throttle to 72 km/h (45 mph) with this speed maintained for 13 minutes. Decelerate to 0 km/h (0 mph). Idle the engine for 2 minutes. Turn OFF the ignition for 1 hour. After 1 hour, turn ON the ignition. IMPORTANT: If a small leak is detected, a minimum of 3 drive cycles may be required before the I/M System Status will update to YES. Repeat numbers 1-8 of this step as necessary. Observe the EVAP System Status with a scan tool. Did the EVAP System Status update to YES?	Go to Step 5	Go to Step 3
3	Observe the DTC Information with a scan tool. Does the scan tool indicate any failed DTCs?	Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information	Go to Step 4
4	Refer to Inspection/Maintenance (I/M) System DTC Table to determine which DTCs are required to run in order to complete this test. Observe the Not Ran Since Code Cleared display with a scan tool. Determine which of the DTCs required for a YES status has not run. Enter the DTC number in the Specific DTC menu of the scan tool. Operate the vehicle within the Conditions for Running the DTC, located in the supporting text for the diagnostic table of the DTC. Repeat numbers 4 and 5 of this step for any additional required DTCs that have not run. Observe the I/M System Status display with a scan tool. Did the EVAP System Status update to YES?	Go to Step 5	Go to Diagnostic Aids
5	Observe the Emission Related DTC portion of the I/M System Status display with a scan tool. Does the scan tool indicate any Emission Related DTCs set?	Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information	System OK

IMPORTANT
Once the engine is started, DO NOT turn the engine OFF for the remainder of the procedure until the test is complete.

CAUTION
Refer to Road Test Caution in Cautions and Notices.

IMPORTANT
In order for this test to run, the vehicle must operate in the following conditions

IMPORTANT
If a small leak is detected, a minimum of 3 drive cycles may be required before the I/M System Status will update to YES. Repeat numbers 1-8 of this step as necessary.

Inspection/Maintenance Evaporative Emission System Set

The purpose of this test is to satisfy the enable criteria necessary to execute inspection/maintenance (I/M) readiness diagnostics for the Heated Oxygen Sensor/Oxygen Sensor (HO2S/O2S) System. The test may be used to set the I/M System Status to YES.

The barometric pressure (BARO) is more than 74 kPa.
The engine coolant temperature (ECT) reaches more than 63°C (144°F).
The engine is running in closed loop fuel control.

If the status does not update, the test outlined in this procedure can be repeated until the I/M System Status updates to YES.

Step	Action	Yes	No
1	Did you perform the Inspection/Maintenance (I/M) System Check?	Go to Step 2	Go to Inspection/Maintenance (I/M) System Check
2	Ensure that the vehicle is within the Conditions for Running specified in the supporting text. Turn OFF all of the accessories, e.g., A/C, blower fan, etc. Start and allow the engine to idle for 2 minutes. CAUTION: Refer to Road Test Caution in Cautions and Notices. In order for this test to run, the vehicle must operate in the following conditions: Acceleration at part throttle from 75-90 km/h (45-55 mph) with this speed maintained for 6 minutes. Deceleration to 0 km/h (0 mph) Review the I/M System Status display with a scan tool. Did the HO2S/O2S System Status update to YES?	Go to Step 5	Go to Step 3
3	With a scan tool, observe the DTC Information. Does the scan tool indicate any failed DTCs?	Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information	Go to Step 4
4	Refer to the Inspection/Maintenance (I/M) System DTC Table to determine which DTCs are required to run in order to complete this test. Observe the Not Ran Since Code Cleared display with the scan tool. Determine which of the DTCs required for a YES status has not run. Enter the DTC number in the Specific DTC menu of the scan tool. Operate the vehicle within the Conditions for Running the DTC, located in the supporting text for the diagnostic table of the DTC. Repeat numbers 4 and 5 of this step for any additional required DTCs that have not run. Observe the I/M System Status display with a scan tool. Did the HO2S/O2S System Status update to YES?	Go to Step 5	Go to Diagnostic Aids
5	Observe the Emission Related DTC portion of the I/M System Status display with a scan tool. Does the scan tool indicate any Emission Related DTCs set?	Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information	System OK

CAUTION
Refer to Road Test Caution in Cautions and Notices.

Inspection/Maintenance Heated Oxygen Sensor/Oxygen Sensor System Set

The purpose of this test is to satisfy the enable criteria necessary to execute inspection/maintenance (I/M) readiness diagnostics for the Heated Oxygen Sensor (HO2S) System. The test may be used to set the I/M System Status to YES.

The battery voltage is more than 10 volts.

If there is an impending failure, the system may require more time to run the diagnostic than was allotted in the set procedure. If the test does not run after numerous attempts and no DTC is set, review the appropriate scan tool data list and the service information for an indication of why the test does not complete. Some tests may abort due to changes in the conditions while the test is running. For example, changes in engine load, such as a cooling fan or an A/C compressor clutch turning ON, may cause the test to abort.

Step	Action	Value(s)	Yes	No
1	Did you perform the Inspection/Maintenance (I/M) System Check?		Go to Step 2	Go to Inspection/Maintenance (I/M) System Check
2	IMPORTANT: Whenever the ignition is turned ON, ignition positive voltage is supplied to the HO2S heaters. After verifying the enable criteria, turn OFF the ignition for approximately 5 minutes to allow the sensors to cool before continuing with the test. Preprogram the scan tool with the vehicle information before the ignition is turned ON. Ensure that the vehicle is within the Conditions for Running specified in the supporting text. Set the vehicle parking brake. Verify that the transmission is in Park for automatic transmissions and Neutral for manual transmissions. Turn OFF all of the accessories, e.g., A/C, blower fan, etc. Start the engine and allow the engine to idle for the specified time. CAUTION: Refer to Road Test Caution in Cautions and Notices. Accelerate at part throttle from 75-90 km/h (45-55 mph) with this speed maintained for 4 minutes. Did the HO2S Heater System Status update to YES?	2 minutes	Go to Step 5	Go to Step 3
3	Observe the DTC information with a scan tool. Does the scan tool indicate any failed DTCs?		Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information	Go to Step 4
4	Refer to Inspection/Maintenance (I/M) System DTC Table to determine which DTCs are required to run in order to complete this test. Observe the Not Ran Since Code Cleared display with a scan tool. Determine which of the DTCs required for a YES status has not run. Enter the DTC number in the Specific DTC menu of the scan tool. Operate the vehicle within the Conditions for Running the DTC, located in the supporting text for the diagnostic table of the DTC. Repeat numbers 4 and 5 of this step for any additional required DTCs that have not run. Observe the I/M System Status display with a scan tool. Did the HO2S Heater System Status update to YES?		Go to Step 5	Go to Diagnostic Aids
5	Observe the Emission Related DTC portion of the I/M System Status display with a scan tool. Does the scan tool indicate any Emission Related DTCs set?		Go to Diagnostic Trouble Code (DTC) List - Vehicle in Vehicle DTC Information	System OK

IMPORTANT
Whenever the ignition is turned ON, ignition positive voltage is supplied to the HO2S heaters. After verifying the enable criteria, turn OFF the ignition for approximately 5 minutes to allow the sensors to cool before continuing with the test.

CAUTION
Refer to Road Test Caution in Cautions and Notices.

Inspection/Maintenance Heated Oxygen Sensor Heater System Set

Engine Controls - 4.6l (lh2) - Troubleshooting Cadillac XLR I

Important Preliminary Inspections Before Starting

Intermittent Conditions

Hard Start

Surges/Chuggles

Lack of Power, Sluggishness, or Sponginess

Detonation/Spark Knock

Hesitation, Sag, Stumble

Cuts Out, Misses

Poor Fuel Economy

Poor Fuel Fill Quality

Rough, Unstable, or Incorrect Idle and Stalling

Dieseling, Run-On

Backfire

Circuit Description

MIL Operation

Test Description

Description

Diagnostic Aids

System Description

Alcohol in Fuel Testing Procedure

Particulate Contaminants in Fuel Testing Procedure

Test Procedure

Conditions for Updating the I/M System Status

Monitored Emission Control Systems

Conditions for Running

Inspection/Maintenance (I/M) System DTC Table

More articles — Engine Performance

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