Engine Controls and Fuel - 4.6l - Troubleshooting & Diagnosis Cadillac STS I рестайлинг

Diagnostic Instructions

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/sts/i-2007-2011/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/sts/i-2007-2011/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/sts/i-2007-2011/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Symptoms Description

Symptoms covers conditions that are not covered by DTCs. Certain conditions can cause multiple symptoms. These conditions are listed together under Symptoms Testing. Conditions that may only cause specific symptoms are listed separately under Additional Symptoms Testing. Perform the Symptoms Testing before using the Additional Symptoms Testing.

Symptoms Verification

Before using the Symptom tables, perform the following inspections

1. Ensure that the engine control module (ECM) and malfunction indicator lamp (MIL) are operating correctly.
2. Ensure that there are no diagnostic trouble codes (DTCs) that are stored.
3. Ensure that the scan tool data is within a normal operating range. Refer to «Control Module References»(/cadillac/sts/i-2007-2011/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for scan tool information.
4. Verify the customer concern.
5. Perform the Visual/Physical Inspection in this section. The visual/physical inspection is extremely important, and can lead to correcting a condition without additional testing. It may also help reveal the cause of an intermittent condition.

Identifying Intermittent Conditions

Many intermittent conditions occur with harness or connector movement due to engine torque, rough pavement, vibration or physical movements of a component. Refer to the following for a list of issues that may cause an intermittent condition

1. Moisture and water intrusion in connectors, terminals, and components
2. Incomplete connector mating
3. Poor terminal contact
4. High circuit or component resistance-High resistance can include any resistance, regardless of the amount, which can interrupt the operation of the component.
5. Harness that is too short or tight.
6. Wire insulation that is chaffed or cut.
7. High or low ambient temperature
8. High or low engine coolant temperatures
9. High underhood temperatures
10. Heat build up in component or circuit due to circuit resistance, poor terminal contact, or high electrical load
11. High or low system voltage
12. High vehicle load conditions
13. Rough road surfaces
14. Electro-magnetic interference (EMI)/circuit interference from relays, solenoids or other electrical surge
15. Incorrect installation of aftermarket, add on accessories

Visual/Physical Check

1. Ensure that the control module grounds are clean, tight, and correctly located. Refer to «Component Connector End Views»(/cadillac/sts/i-2007-2011/remont/body-electrical/#wiring-systems-and-power-management-diagnostic-starting-point-connector-end-views) .
2. Ensure that the vacuum hoses are not split, kinked, and improperly connected. Refer to «Evaporative Emissions Hose Routing Diagram»(/cadillac/sts/i-2007-2011/remont/testing-diagnostics/#engine-controls-and-fuel-44l-introduction) .
3. Ensure that the air filter is clean and free from restrictions.
4. Ensure that there is no water intrusion in connectors terminals and components.
5. Inspect the air intake ducts for the following conditions: Collapsed Damaged areas Looseness Incorrect installation Leaking
6. Inspect for air leaks at the throttle body mounting area, the mass air flow (MAF) sensor and intake manifold sealing surfaces.
7. Inspect the wiring harness for the following conditions: Poor connections Pinches Cuts
8. Inspect for loose, damaged, unseated, or missing sensors/components.
9. Inspect the terminals for corrosion and correct contact.

Symptoms Testing

Backfire, Cuts Out/Misses, Detonation/Spark Knock, Dieseling/Run-On, Hard Start, Hesitation/Sag/Stumble, Lack of Power/Sluggishness/Sponginess, Poor Fuel Economy, Rough, Unstable, or Incorrect Idle and Stalling, or Surges/Chuggles

1. Test the fuel system for the following: The fuel system for correct operation volume and pressure-Refer «Fuel System Diagnosis»(/cadillac/sts/i-2007-2011/remont/testing-diagnostics/#engine-controls-and-fuel-46l-troubleshooting-diagnosis) . The fuel injectors for proper operation-Refer to «Fuel Injector Diagnosis (W/CH47976)»(/cadillac/sts/i-2007-2011/remont/testing-diagnostics/#engine-controls-and-fuel-46l-troubleshooting-diagnosis) or «Fuel Injector Diagnosis (W/J39021 or Tech 2)»(/cadillac/sts/i-2007-2011/remont/testing-diagnostics/#engine-controls-and-fuel-46l-troubleshooting-diagnosis) . The fuel quality condition-Refer to «Alcohol/Contaminants-in-Fuel Diagnosis»(/cadillac/sts/i-2007-2011/remont/testing-diagnostics/#engine-controls-and-fuel-44l-troubleshooting-diagnosis) .
2. Test ignition system for the following: Proper ignition system operation-Refer to «Electronic Ignition (EI) System Diagnosis»(/cadillac/sts/i-2007-2011/remont/testing-diagnostics/#engine-controls-and-fuel-46l-troubleshooting-diagnosis) . Spark plugs-Refer to «Spark Plug Inspection»(/cadillac/sts/i-2007-2011/remont/testing-diagnostics/#engine-controls-and-fuel-44l-introduction) . Spark plugs for correct application-Refer to «Ignition System Specifications»(/cadillac/sts/i-2007-2011/remont/testing-diagnostics/#engine-controls-and-fuel-46l-introduction__ignition-system-specifications) .
3. Inspect for the following conditions: The proper operation of the transmission torque converter clutch (TCC)-The scan tool should indicate an engine speed drop when the TCC is commanded ON. The proper operation of the A/C compressor. Items that can cause an engine to run lean or rich- Refer to «DTC P0171, P0172, P0174, or P0175»(/cadillac/sts/i-2007-2011/remont/testing-diagnostics/#engine-controls-and-fuel-46l-dtc-p0010-to-dtc-p0333) . The crankshaft position (CKP) sensor for proper operation. The proper operation of the knock sensor (KS) system Inspect the exhaust system. Refer to «Symptoms - Engine Exhaust»(/cadillac/sts/i-2007-2011/remont/exhaust/#engine-exhaust-system__symptoms-engine-exhaust) . Electromagnetic interference (EMI) on the reference circuit can cause a misfire condition. You can usually detect EMI with a scan tool by monitoring the engine speed parameter. A sudden increase in the engine speed parameter with little change in actual engine speed indicates that EMI is present. Inspect the high voltage components near the ignition control circuit if a condition exists. The crankcase ventilation valve for proper operation. Inspect for a clean throttle body. Coking on the throttle body can cause a symptom. Refer to «Throttle Body Inspection and Cleaning»(/cadillac/sts/i-2007-2011/remont/testing-diagnostics/#engine-controls-and-fuel-46l-introduction__throttle-body-inspection-and-cleaning) . The proper operation of the evaporative emission (EVAP) canister purge solenoid. The proper operation of the engine cooling system-Refer to «Symptoms - Engine Cooling»(/cadillac/sts/i-2007-2011/remont/cooling-system-mechanical/#engine-cooling-system__symptoms-engine-cooling) .
4. Inspect the engine for the following mechanical failures: Refer to «Symptoms - Engine Mechanical»(/cadillac/sts/i-2007-2011/remont/mechanical/#engine-mechanical-46l-1-of-6) . Excessive oil in the combustion chamber or leaking valve seals Oil Consumption Incorrect cylinder compression Sticking or leaking valves Worn camshaft lobes Incorrect valve timing Worn rocker arms Broken valve springs Excessive carbon buildup in the combustion chambers-Clean the chambers with top engine cleaner. Follow the instructions on the can. Incorrect engine parts
5. If the above conditions do not address the symptom, refer to the additional symptoms tests.

Additional Symptoms Tests

Hard Start

1. Verify that the engine coolant temperature (ECT) has not shifted in value. Refer to «Temperature Versus Resistance»(/cadillac/sts/i-2007-2011/remont/testing-diagnostics/#engine-controls-and-fuel-44l-introduction__temperature-versus-resistance) .
2. Verify the engine electrical system for correct operation. Refer to «Symptoms - Engine Electrical»(/cadillac/sts/i-2007-2011/remont/charging-system/#battery-charging-system-and-starting-system__symptoms-engine-electrical) .
3. Verify that the driver is using the correct starting procedure as described in the owners manual.
4. Verify that there is adequate fuel.
5. 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»(/cadillac/sts/i-2007-2011/remont/mechanical/#engine-mechanical-46l-4-of-6) .

Hesitation, Sag, Stumble

1. Inspect the mass air flow (MAF) sensor for obstruction, contamination, and damage.
2. Test the generator. Refer to «Symptoms - Engine Electrical»(/cadillac/sts/i-2007-2011/remont/charging-system/#battery-charging-system-and-starting-system__symptoms-engine-electrical) . Repair the charging system if the generator output voltage is less than 9 volts or more than 16 volts.
3. 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»(/cadillac/sts/i-2007-2011/remont/mechanical/#engine-mechanical-46l-4-of-6) .

Poor Fuel Economy

1. Heavy loads being carried or towed
2. Acceleration rate too much or too often
3. Inspect the brake system for brake drag.
4. Inspect for incorrect operation of the speedometer.
5. Verify that the engine coolant temperature (ECT) has not shifted in value. Refer to «Temperature Versus Resistance»(/cadillac/sts/i-2007-2011/remont/testing-diagnostics/#engine-controls-and-fuel-44l-introduction__temperature-versus-resistance) .
6. Inspect the mass air flow (MAF) sensor for obstruction, contamination, and damage.
7. Inspect for foreign material accumulation in the throttle bore, and for carbon deposits on the throttle plate and shaft. Also inspect for throttle body tampering. Refer to «Throttle Body Inspection and Cleaning»(/cadillac/sts/i-2007-2011/remont/testing-diagnostics/#engine-controls-and-fuel-46l-introduction__throttle-body-inspection-and-cleaning) .

Detonaton/Spark Knock

1. Test for an engine overheating condition. Refer to «Symptoms - Engine Cooling»(/cadillac/sts/i-2007-2011/remont/cooling-system-mechanical/#engine-cooling-system__symptoms-engine-cooling) .
2. Verify that the engine coolant temperature (ECT) has not shifted in value. Refer to «Temperature Versus Resistance»(/cadillac/sts/i-2007-2011/remont/testing-diagnostics/#engine-controls-and-fuel-44l-introduction__temperature-versus-resistance) .
3. If there are no engine mechanical faults, fill the fuel tank with a known high quality fuel that meets the vehicle minimum octane requirements.

Lack of Power, Hesitation, or Cut Out

1. Inspect the engine electrical system for correct operation. Refer to «Symptoms - Engine Electrical»(/cadillac/sts/i-2007-2011/remont/charging-system/#battery-charging-system-and-starting-system__symptoms-engine-electrical) .
2. Verify that each injector harness is connected to the correct injector.
3. Inspect the mass air flow (MAF) sensor for obstruction, contamination, and damage.

Rough, Unstable, or Incorrect Idle and Stalling

1. Inspect the mass air flow (MAF) sensor for obstruction, contamination, and damage.
2. Inspect the engine mounts.
3. Inspect the intake and exhaust manifolds for casting flash.

Surges/Chuggles

1. Inspect the mass air flow (MAF) sensor for obstruction, contamination, and damage.
2. Test the heated oxygen sensors (HO2S). The HO2S should respond quickly to a change in throttle position. If the HO2S do not respond to different throttle positions, inspect for contamination from fuel, silicon, or the incorrect use of RTV sealant. The sensors may have a white powdery coating and result in a high, but false, signal voltage, which gives a rich exhaust indication. The ECM reduces the amount of fuel delivered to the engine, causing a driveability condition.
3. Verify that each injector harness is connected to the correct injector.

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/sts/i-2007-2011/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/sts/i-2007-2011/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/sts/i-2007-2011/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Circuit/System Description

The malfunction indicator lamp (MIL) is located on the instrument panel cluster (IPC). The MIL informs the driver that an emission system fault has occurred and that the engine control system requires service. The engine control module (ECM) monitors the MIL control circuit for conditions that are incorrect for the commanded states of the MIL. For example, a failure condition exists if the ECM detects low voltage when the MIL is commanded OFF, or high voltage when the MIL is commanded ON.

Diagnostic Aids

If the condition is intermittent, move the related harnesses and connectors with the engine operating. Monitor the scan tool Circuit Test Status parameters for the component. The Circuit Test Status parameter will change from OK or Not Run to Fault if there is a condition with the circuit or a connection.

Reference Information

Schematic Reference

1. «Engine Controls Schematics»(/cadillac/sts/i-2007-2011/remont/testing-diagnostics/#engine-controls-and-fuel-46l-introduction)
2. «Instrument Cluster Schematics»(/cadillac/sts/i-2007-2011/remont/gauges-instrument-panels/#instrument-panel-system-displays-gauges)

Connector End View Reference

Component Connector End Views

Electrical Information Reference

1. «Circuit Testing»(/cadillac/sts/i-2007-2011/remont/body-electrical/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/cadillac/sts/i-2007-2011/remont/body-electrical/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/sts/i-2007-2011/remont/body-electrical/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/cadillac/sts/i-2007-2011/remont/body-electrical/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Circuit/System Verification

1. Ignition ON, command the MIL ON and OFF with a scan tool. The MIL should turn ON and OFF as commanded.
2. Command the MIL ON and OFF with a scan tool while observing the following control circuit status parameters: MIL Ckt. Short Gnd Test Status MIL Ckt. Open Test Status MIL Ckt. Short Volts Test Status Each parameter should change between OK to Not run or from Not Run to OK.

Circuit/System Testing

1. Ignition ON, verify that the IPC warning indicators are illuminated. If the IPC warning indicators are not illuminated, test the IPC ignition circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition circuit fuse is open, replace the IPC.
2. Ignition OFF, disconnect the ECM X1 harness connector. Ignition ON, the MIL should not illuminate. If the MIL is illuminated, test the MIL control circuit terminal X1-12 for a short to ground. If the circuit tests normal, replace the IPC.
3. Ignition ON, connect a 3A fused jumper wire between the MIL control circuit terminal X1-12 and ground. The MIL should illuminate. If the MIL does not illuminate, test the MIL control circuit for a short to voltage, or an open/high resistance. If the circuit tests normal, replace the IPC/bulb.
4. If all circuits/connections test normal, replace the ECM.

Repair Procedures

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Instrument Cluster Replacement»(/cadillac/sts/i-2007-2011/remont/gauges-instrument-panels/#instrument-panel-system-displays-gauges)
2. «Control Module References»(/cadillac/sts/i-2007-2011/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for ECM or IPC replacement, setup, and programming

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/sts/i-2007-2011/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/sts/i-2007-2011/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/sts/i-2007-2011/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

This Engine Cranks but Does Not Run is an organized approach to identify a condition which causes the engine to crank but does not continue to run. This diagnostic directs the technician to the appropriate system diagnosis.

This diagnostic assumes the system voltage levels are adequate for starter motor operation. Refer to Battery Inspection/Test , and Engine Cranks Slowly . Fuel level and fuel quality should be determined for correct diagnosis.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

1. «Circuit Testing»(/cadillac/sts/i-2007-2011/remont/body-electrical/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/cadillac/sts/i-2007-2011/remont/body-electrical/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/sts/i-2007-2011/remont/body-electrical/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/cadillac/sts/i-2007-2011/remont/body-electrical/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)
5. «Starting System Description and Operation»(/cadillac/sts/i-2007-2011/remont/charging-system/#battery-charging-system-and-starting-system__starting-system-description-and-operation)

Scan Tool Reference

Control Module References for scan tool information

Special Tools

1. CH-48027 Digital Fuel Pressure Gage
2. J 26792 HEI Spark Tester

Attempt to start the engine. The engine should start and run.

1. Crank the engine for up to 15 seconds.
2. Observe the Engine DTC information with a scan tool. If DTCs P0033, P0102, P0171, P0201-P0208, P0230, P0335, P0336, P0340, P0403, P0404, P0443, P0601, P0602, P0603, P0604, P0606, P0607, P060D, P062F, P0641, P0651, P0685, P0689, P0690, P1516, P1682, P2610 are set, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/cadillac/sts/i-2007-2011/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2__diagnostic-trouble-code-dtc-list) to diagnose those DTCs.
3. Ignition OFF for 90 seconds, determine the current vehicle testing altitude. Ignition ON, observe the scan tool MAP Sensor parameter. Compare the parameter to the «Altitude Versus Barometric Pressure»(/cadillac/sts/i-2007-2011/remont/testing-diagnostics/#engine-controls-and-fuel-36l-introduction__altitude-versus-barometric-pressure) table. The MAP sensor pressure parameter should be within the specified range indicated in the table. If the reading is not correct for your altitude, diagnose the MAP sensor. Refer to «DTC P0106»(/cadillac/sts/i-2007-2011/remont/testing-diagnostics/#engine-controls-and-fuel-46l-dtc-p0010-to-dtc-p0333) .
4. Install a J 26792 .
5. Crank the engine for 15 seconds. Spark should be observed from the J 26792 . If spark is not observed refer to «Electronic Ignition (EI) System Diagnosis»(/cadillac/sts/i-2007-2011/remont/testing-diagnostics/#engine-controls-and-fuel-46l-troubleshooting-diagnosis) .
6. Command the fuel pump ON and OFF. Fuel pump should energize when commanded ON and De-energize when commanded OFF. If the fuel pump does not respond refer to «Fuel System Diagnosis»(/cadillac/sts/i-2007-2011/remont/testing-diagnostics/#engine-controls-and-fuel-46l-troubleshooting-diagnosis) .
7. Turn OFF the ignition.
8. Install the CH-48027 . Turn ON the ignition and command the fuel pump ON while observing the CH-48027 . Refer to «Fuel Pressure Gage Installation and Removal»(/cadillac/sts/i-2007-2011/remont/testing-diagnostics/#engine-controls-and-fuel-46l-introduction) . The fuel pressure should be between 384-425 kPa (55-61 psi). If the fuel pressure is not within 384-425 kPa (55-61 psi), refer to «Fuel System Diagnosis»(/cadillac/sts/i-2007-2011/remont/testing-diagnostics/#engine-controls-and-fuel-46l-troubleshooting-diagnosis) .
9. Inspect for the following conditions: Compare the actual engine coolant temperature to the ECT parameter. Air filter and air intake system for restrictions and obstructions Test the fuel for contamination. Refer to «Alcohol/Contaminants-in-Fuel Diagnosis»(/cadillac/sts/i-2007-2011/remont/testing-diagnostics/#engine-controls-and-fuel-44l-troubleshooting-diagnosis) . Inspect the spark plugs. Refer to «Spark Plug Inspection»(/cadillac/sts/i-2007-2011/remont/testing-diagnostics/#engine-controls-and-fuel-44l-introduction) . Test the exhaust system for restrictions. Refer to «Restricted Exhaust»(/cadillac/sts/i-2007-2011/remont/exhaust/#engine-exhaust-system) . Engine mechanical conditions such as worn timing chain gears, low compression, etc.-Refer to «Engine Compression Test»(/cadillac/sts/i-2007-2011/remont/mechanical/#engine-mechanical-44l-1-of-6) .

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Poor Fuel Fill Quality

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/sts/i-2007-2011/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/sts/i-2007-2011/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/sts/i-2007-2011/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Diagnostic Fault Information

The control module enables the fuel pump relay when the ignition switch is turned ON. The control module will disable the fuel pump relay within 2 seconds unless the control module detects ignition reference pulses. The control module continues to enable the fuel pump relay as long as ignition reference pulses are detected. The control module disables the fuel pump relay within 2 seconds if ignition reference pulses cease to be detected and the ignition remains ON.

The following conditions may cause the fuel pump fuse to open

1. The fuse is faulty.
2. There is an intermittent short to ground in the supply voltage circuit of the fuel pump.
3. The fuel pump has an intermittent internal condition.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

1. «Circuit Testing»(/cadillac/sts/i-2007-2011/remont/body-electrical/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/cadillac/sts/i-2007-2011/remont/body-electrical/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/sts/i-2007-2011/remont/body-electrical/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/cadillac/sts/i-2007-2011/remont/body-electrical/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Note. An open or a short to voltage in the control circuit will cause both the Ckt. Open Test Status and the Ckt. Short Volts Test Status parameters to display Fault.

Ignition ON, command the fuel pump relay ON and OFF with a scan tool while observing the following control circuit status parameters

1. Fuel Pump Relay Ckt. Short Gnd Test Status
2. Fuel Pump Relay Ckt. Open Test Status
3. Fuel Pump Relay Ckt. Short Volts Test Status

Each parameter should toggle between OK and Not Run or Not Run and OK.

1. With the ignition OFF, remove the fuel pump relay from the rear electrical center.
2. Test for less than 5 ohms of resistance between the ground circuit and ground. If greater than the specified range, test the ground circuit for an open/high resistance.
3. Connect a test lamp between the fuel pump relay control circuit and the ground circuit. Command the fuel pump relay ON and OFF with a scan tool. The test lamp should turn ON and OFF when changing between the commanded states. If the test lamp is always ON, test the control circuit for a short to voltage. If the circuit tests normal, replace the ECM. If the test lamp is always OFF, test the control circuit for a short to voltage. If the circuit tests normal, replace the ECM.
4. Inspect the fuel pump fuse. If the fuel pump fuse is open, test for the following conditions: A short to ground in the relay switch B+ circuit A short to ground in the supply voltage circuit of the fuel pump If the above circuits test normal, replace the fuel sender.
5. Verify that a test light illuminates between the B+ circuit and ground. If the test lamp does not illuminate, test the B+ circuit for an open/high resistance.
6. Connect a 15A fused jumper wire between the B+ circuit and the supply voltage circuit of the fuel pump. Verify the fuel pump is activated. If the fuel pump does not activate, test for the following conditions: An open/high resistance in the supply voltage circuit of the fuel pump An open/high resistance in the ground circuit of the fuel pump If the above circuits test normal, replace the fuel sender.
7. If all circuits test normal, test or replace the fuel pump relay.

Component Testing

1. Measure for 70-100 ohms of resistance between terminals 85 and 86 of the fuel pump relay. If the resistance is not within the specified range, replace the fuel pump relay.
2. Measure for infinite resistance between the following terminals of the fuel pump relay: 30 and 86 30 and 87 30 and 85 85 and 87 If continuity is detected, replace the fuel pump relay.
3. Connect a 15A fused jumper wire from the positive terminal of the battery to relay terminal 85. Connect a jumper wire from the negative terminal of the battery to relay terminal 86. Measure for less than 2 ohms between terminals 30 and 87 of the relay. If the resistance measures more than 2 ohms, replace the fuel pump relay.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Primary Fuel Tank Module Replacement»(/cadillac/sts/i-2007-2011/remont/testing-diagnostics/#engine-controls-and-fuel-46l-introduction)
2. «Control Module References»(/cadillac/sts/i-2007-2011/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for ECM replacement, setup, and programming

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/sts/i-2007-2011/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/sts/i-2007-2011/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/sts/i-2007-2011/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The control module enables the fuel pump relay when the ignition switch is turned ON. The control module will disable the fuel pump relay within 2 seconds unless the control module detects ignition reference pulses. The control module continues to enable the fuel pump relay as long as ignition reference pulses are detected. The control module disables the fuel pump relay within 2 seconds if ignition reference pulses cease to be detected and the ignition remains ON.

The fuel system is a semi-returnless design. The fuel pressure regulator is a part of the fuel sender assembly, eliminating the need for a return pipe from the engine. A semi-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.

The fuel tank stores the fuel supply. The fuel pump is an electric pump that is attached to the primary fuel tank module assembly. The fuel pump also supplies fuel to the siphon jet pump, also attached to the primary fuel tank module. The siphon jet pump draws fuel from the secondary side of the fuel tank to the primary side of the fuel tank. The fuel pump is designed to provide fuel at a pressure above the pressure that is needed by the fuel injectors. A fuel pressure regulator which is also located in the fuel tank, is attached to the primary fuel tank module. The fuel pressure regulator keeps the fuel available to the fuel injectors at a regulated pressure. Unused fuel is returned from the fuel filter to the fuel tank by a separate fuel return pipe.

Electrical Information Reference

1. «Circuit Testing»(/cadillac/sts/i-2007-2011/remont/body-electrical/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/cadillac/sts/i-2007-2011/remont/body-electrical/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/sts/i-2007-2011/remont/body-electrical/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/cadillac/sts/i-2007-2011/remont/body-electrical/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Special Tools

1. CH 48027: Digital Pressure Gage
2. J 37287: Fuel Line Shut-off Adapter

Note. Inspect the fuel system for damage or external leaks before proceeding. Verify that adequate fuel is in the fuel tank before proceeding. The fuel pump relay may need to be commanded ON a few times in order to obtain the highest possible fuel pressure. Before proceeding with this test, review the User Manual CH 48027-5 for Safety Information and Instructions.

1. Ignition ON, engine OFF, command the fuel pump relay ON with a scan tool. You should hear the fuel pump turn ON and OFF. If the fuel pump does not operate, refer to «Fuel Pump Electrical Circuit Diagnosis»(/cadillac/sts/i-2007-2011/remont/testing-diagnostics/#engine-controls-and-fuel-46l-troubleshooting-diagnosis) .
2. Ignition OFF, all accessories OFF, install a CH 48027: Gage. Refer to «Fuel Pressure Gage Installation and Removal»(/cadillac/sts/i-2007-2011/remont/testing-diagnostics/#engine-controls-and-fuel-46l-introduction) .
3. Ignition ON, engine OFF, command the fuel pump relay ON with a scan tool. Verify the fuel pressure is between 384-425 kPa (55-62 psi) and does not decrease more than 34 kPa (5 psi) in 1 minute.

1. Ignition ON, engine OFF, command the fuel pump relay ON with a scan tool and observe the fuel pressure gage while the fuel pump is operating. Verify the fuel pressure is between 384-425 kPa (55-62 psi). If the fuel pressure is greater than the specified range, replace the fuel pump module. If the fuel pressure is less than the specified range, test, inspect, and repair the items listed below. If all items test normal, replace the fuel pump module. Restricted fuel feed pipe Restricted or plugged strainer Inspect the harness connectors and the ground circuits of the fuel pump for poor connections.
2. Verify that the fuel pressure does not decrease more than 34 kPa (5 psi) in 1 minute. If the fuel pressure decreases more than the specified value, perform the following procedure: Ignition OFF, relieve the fuel pressure. Refer to «Fuel Pressure Relief (With CH 48027)»(/cadillac/sts/i-2007-2011/remont/testing-diagnostics/#engine-controls-and-fuel-46l-introduction) or «Fuel Pressure Relief (Without CH 48027)»(/cadillac/sts/i-2007-2011/remont/testing-diagnostics/#engine-controls-and-fuel-46l-introduction__fuel-pressure-relief-without-ch-48027) . Install the J 37287: Adapter between the fuel feed pipe and the fuel rail. Open the valve on the J 37287: Adapter Ignition ON, command the fuel pump relay ON with a scan tool and bleed the air from the CH 48027: Gage. Command the fuel pump relay ON and then OFF with a scan tool. Close the valve on the J 37287: Adapter. Monitor the fuel pressure for 1 minute. If the fuel pressure decreases more than 34 kPa (5 psi) within the specified time, locate and replace the leaking fuel injector(s). If the fuel pressure does not decrease more than 34 kPa (5 psi) within the specified time, replace the fuel pump module.
3. Relieve the fuel pressure to 69 kPa (10 psi). Verify that the fuel pressure does not decrease more than 14 kPa (2 psi) in 5 minutes. If the fuel pressure decreases more than the specified value, replace the primary fuel pump module.
4. Remove the J 37287: Adapter and CH 48027: Gage. Refer to «Fuel Pressure Gage Installation and Removal»(/cadillac/sts/i-2007-2011/remont/testing-diagnostics/#engine-controls-and-fuel-46l-introduction) .
5. Operate the vehicle within the conditions of the customer concern while monitoring the fuel pressure with the CH 48027: Gage. The fuel pressure should not drop off during acceleration, cruise or hard cornering. If the fuel pressure drops off, test, inspect, and repair the items listed below. If all items test normal, replace the primary fuel pump module. Restricted fuel feed pipe Restricted or plugged strainer Inspect the harness connectors and the ground circuits of the fuel pump for poor connections
6. If the fuel system tests normal, refer to «Symptoms - Engine Controls»(/cadillac/sts/i-2007-2011/remont/testing-diagnostics/#engine-controls-and-fuel-46l-troubleshooting-diagnosis) .

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Fuel Injector and Fuel Rail Replacement»(/cadillac/sts/i-2007-2011/remont/testing-diagnostics/#engine-controls-and-fuel-46l-introduction)
2. «Primary Fuel Level Sensor Replacement»(/cadillac/sts/i-2007-2011/remont/testing-diagnostics/#engine-controls-and-fuel-46l-introduction)

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/sts/i-2007-2011/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/sts/i-2007-2011/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/sts/i-2007-2011/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The control module enables the appropriate fuel injector pulse for each cylinder. The 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 the 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.

The Active Fuel Injector Tester (AFIT), CH 47976, is used to test the fuel pump, fuel system leak down, and the fuel injectors. Following the User Guide, CH 47976-11, and the on screen prompts or selections, will indicate the steps required to perform each of the available tests. The tester will perform all of the tests automatically and display results of the test. The results can also be down loaded for storage and printing.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

1. «Circuit Testing»(/cadillac/sts/i-2007-2011/remont/body-electrical/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/cadillac/sts/i-2007-2011/remont/body-electrical/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/sts/i-2007-2011/remont/body-electrical/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/cadillac/sts/i-2007-2011/remont/body-electrical/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Special Tools

CH 47976: Active Fuel Injector Tester (AFIT)

Fuel Injector Coil Test

Verify the resistance of each fuel injector with one of the following methods

1. If the engine coolant temperature (ECT) sensor is between 10-32°C (50-90°F), the resistance of each fuel injector should be 11-14 ohms. If the injectors measure OK, perform the «AFIT Test Procedure»(/cadillac/sts/i-2007-2011/remont/testing-diagnostics/#engine-controls-and-fuel-46l-troubleshooting-diagnosis__afit-test-procedure) . If not within the specified range, replace the fuel injector.
2. If the ECT sensor is not between 10-32°C (50-90°F), measure and record the resistance of each fuel injector with a DMM. Subtract the lowest resistance value from the highest resistance value. The difference between the lowest value and the highest value should be equal to or less than 3 ohms. If the difference is equal to or less than 3 ohms, perform the «AFIT Test Procedure»(/cadillac/sts/i-2007-2011/remont/testing-diagnostics/#engine-controls-and-fuel-46l-troubleshooting-diagnosis__afit-test-procedure) . If the difference is more than 3 ohms, 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.

Note. DO NOT perform this test if the engine coolant temperature (ECT) is above 94°C (201°F). Irregular fuel pressure readings may result due to hot soak fuel boiling. Verify that adequate fuel is in the fuel tank before proceeding with this diagnostic.

AFIT Test Procedure

1. Turn OFF all accessories.
2. Turn OFF the ignition.
3. Install the CH 47976: AFIT. Refer to the AFIT User Guide.
4. Turn ON the AFIT and select the vehicle.
5. Turn ON the ignition and perform the Injector Test. If the AFIT aborts testing due to fuel pressure or fuel leak down, refer to «Fuel System Diagnosis»(/cadillac/sts/i-2007-2011/remont/testing-diagnostics/#engine-controls-and-fuel-46l-troubleshooting-diagnosis) .
6. View the test results. If any injector exceeds the recommended tolerance, replace the injector(s).

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Fuel Injector and Fuel Rail Replacement

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/sts/i-2007-2011/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/sts/i-2007-2011/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/sts/i-2007-2011/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The control module enables the appropriate fuel injector pulse for each cylinder. The 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 the 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.

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

1. Monitoring the misfire current counters, or misfire graph, may help to isolate the fuel injector that is causing the condition.
2. Operating the vehicle over a wide temperature range may help isolate the fuel injector that is causing the condition.
3. Perform the fuel injector coil test within the conditions of the customer's concern. A fuel injector condition may only be apparent at a certain temperature, or under certain conditions.

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

1. «Circuit Testing»(/cadillac/sts/i-2007-2011/remont/body-electrical/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/cadillac/sts/i-2007-2011/remont/body-electrical/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/sts/i-2007-2011/remont/body-electrical/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/cadillac/sts/i-2007-2011/remont/body-electrical/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Special Tools

1. CH 48027: Digital Pressure Gage
2. J 39021: Fuel Injector Coil and Balance Tester
3. J 44602: Injector Test Adapter

Verify the resistance of each fuel injector with one of the following methods

1. If the engine coolant temperature (ECT) sensor is between 10-32°C (50-90°F), the resistance of each fuel injector should be 11-14 ohms. If the resistance of any fuel injector is not 11-14 ohms, replace the fuel injector.
2. If the ECT sensor is not between 10-32°C (50-90°F), measure and record the resistance of each fuel injector with a DMM. Subtract the lowest resistance value from the highest resistance value. The difference between the lowest value and the highest value should be equal to or less than 3 ohms. If the difference is equal to or less than 3 ohms, refer to «Fuel Injector Balance Test-Fuel Pressure Test»(/cadillac/sts/i-2007-2011/remont/testing-diagnostics/#engine-controls-and-fuel-46l-troubleshooting-diagnosis__fuel-injector-balance-test-fuel-pressure-test) for further diagnosis of the fuel injectors. If the difference is more than 3 ohms, 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 and the highest individual fuel injector resistance values from the average resistance value. Replace the fuel injector that displays the greatest resistance difference above or below the average.

Note. DO NOT perform this test if the engine coolant temperature (ECT) is above 94°C (201°F). Irregular fuel pressure readings may result due to hot soak fuel boiling. Verify that adequate fuel is in the fuel tank before proceeding with this diagnostic. Before proceeding with this test review the User Manual CH 48027-5 for Safety Information and Instructions.

Fuel Injector Balance Test-Fuel Pressure Test

1. Install a CH 48027: Gage. Refer to «Fuel Pressure Gage Installation and Removal»(/cadillac/sts/i-2007-2011/remont/testing-diagnostics/#engine-controls-and-fuel-46l-introduction) .
2. Turn ON the ignition, with the engine OFF.
3. Command the fuel pump relay ON with a scan tool.
4. Observe the fuel pressure gage with the fuel pump commanded ON. The fuel pressure should be 384-425 kPa (55-62 psi). If the fuel pressure is not 384-425 kPa (55-62 psi), refer to «Fuel System Diagnosis»(/cadillac/sts/i-2007-2011/remont/testing-diagnostics/#engine-controls-and-fuel-46l-troubleshooting-diagnosis) .
5. Monitor the fuel pressure gage for one minute. The fuel pressure should not decrease more than 34 kPa (5 psi). If the fuel pressure decreases more than 34 kPa (5 psi), refer to «Fuel System Diagnosis»(/cadillac/sts/i-2007-2011/remont/testing-diagnostics/#engine-controls-and-fuel-46l-troubleshooting-diagnosis) .
6. Perform the «Fuel Injector Balance Test with Special Tool»(/cadillac/sts/i-2007-2011/remont/testing-diagnostics/#engine-controls-and-fuel-46l-troubleshooting-diagnosis__fuel-injector-balance-test-with-special) or the «Fuel Injector Balance Test with Tech 2»(/cadillac/sts/i-2007-2011/remont/testing-diagnostics/#engine-controls-and-fuel-46l-troubleshooting-diagnosis__fuel-injector-balance-test-with-tech) .

Fuel Injector Balance Test with Special Tool

1. Set the amperage supply selector switch on the fuel injector tester to the Balance Test 0.5-2.5 amp position.
2. Connect the J 39021: Tester to a fuel injector with a J 44602: Adapter.
3. Command the fuel pump relay ON and then OFF 3 times with a scan tool. On the last command, as the fuel pressure begins to slowly degrade and stabilize, select a fuel pressure within 34 kPa (5 psi) of the maximum pump pressure. Record this fuel pressure. This is the starting pressure at which you will pulse each injector.
4. Command the fuel pump relay ON one more time and energize the fuel injector by depressing the Push to Start Test button on the J 39021: Tester at the previously selected pressure.
5. After the injector stops pulsing, select Min from the Display Mode and record the Min pressure.
6. Clear the Min/Max results.
7. Select Normal from the Display Mode.
8. Repeat steps 2 and 4 through 7 for each fuel injector.
9. Perform the «Pressure Drop Calculation»(/cadillac/sts/i-2007-2011/remont/testing-diagnostics/#engine-controls-and-fuel-46l-troubleshooting-diagnosis__pressure-drop-calculation) .

Fuel Injector Balance Test with Tech 2

1. Command the fuel pump relay ON and then OFF three times with a scan tool. On the last command, as the fuel pressure begins to slowly degrade and stabilize, select a fuel pressure within 34 kPa (5 psi) of the maximum pump pressure. Record this fuel pressure. This is the starting pressure at which you will pulse each injector.
2. With a scan tool, select the Fuel Injector Balance Test function within the Special Functions menu.
3. Select an injector to be tested.
4. Press Enter to prime the fuel system.
5. Energize the fuel injector by depressing the Pulse Injector button on the scan tool at the previously selected pressure.
6. After the injector stops pulsing, select Min from the Display Mode on the CH 48027: Gage and record the Min pressure.
7. Clear the Min/Max results on the CH 48027: Gage.
8. Select Normal from the Display Mode on the CH 48027: Gage.
9. Press Enter on the scan tool to bring you back to the Select Injector screen.
10. Repeat steps 3 through 9 for each fuel injector.
11. Perform the Pressure Drop Calculation down below.

Pressure Drop Calculation

1. Subtract the minimum pressure from the starting pressure for one fuel injector. The result is the pressure drop value.
2. Obtain a pressure drop value for each fuel injector.
3. Add all of the individual pressure drop values except for the injector suspected of being faulty. This is the total pressure drop.
4. Divide the total pressure drop by the number of fuel injectors that were added together. This is the average pressure drop. The difference between any individual pressure drop and the average pressure drop should not be more than 20 kPa (3 psi). If the difference between any individual pressure drop and the average pressure drop is more than 20 kPa (3 psi), replace the fuel injector.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Fuel Injector and Fuel Rail Replacement

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/sts/i-2007-2011/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/sts/i-2007-2011/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/sts/i-2007-2011/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Test Description

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.

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.

Special Tools Required

J 44175: Fuel Composition Tester

System Verification

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.

1. If the sample appears cloudy, or contaminated with water, as indicated by a water layer at the bottom of the sample, perform the «Particulate Contaminants in Fuel Testing Procedure»(/cadillac/sts/i-2007-2011/remont/testing-diagnostics/#engine-controls-and-fuel-46l-troubleshooting-diagnosis__particulate-contaminants-in-fuel-testing-procedure) .
2. If alcohol contamination is suspected, perform the «Alcohol in Fuel Testing with Special Tool»(/cadillac/sts/i-2007-2011/remont/testing-diagnostics/#engine-controls-and-fuel-46l-troubleshooting-diagnosis__alcohol-in-fuel-testing-with-special) .

Alcohol in Fuel Testing with Special Tool

1. Test the fuel composition using J 44175: Tester and Instruction Manual.
2. If water appears in the fuel sample, clean the fuel system.
3. Subtract 50 from the reading on the DMM in order to obtain the percentage of alcohol in the fuel sample.
4. If the fuel sample contains more than 15 percent ethanol, add fresh, regular gasoline to the vehicle's fuel tank.
5. Test the fuel composition.
6. If testing shows the ethanol percentage is still more than 15 percent, replace the fuel in the vehicle.

Alcohol in Fuel Testing without Special Tool

1. Using a 100 ml (3.38 oz) specified cylinder with 1 ml (0.034 oz) graduation marks, fill the cylinder with fuel to the 90 ml (3.04 oz) mark.
2. Add 10 ml (0.34 oz) of water in order to bring the total fluid volume to 100 ml (3.38 oz) and install a stopper.
3. Shake the cylinder vigorously for 10-15 seconds.
4. Carefully loosen the stopper in order to release the pressure.
5. Re-install the stopper and shake the cylinder vigorously again for 10-15 seconds.
6. 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

1. Using an approved fuel container, draw approximately 0.5 liter (0.53 qt) of fuel.
2. Place the container 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 any physical contaminants or water are present, clean the fuel system.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Alcohol/Contaminants-in-Fuel Diagnosis

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/sts/i-2007-2011/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/sts/i-2007-2011/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/sts/i-2007-2011/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The ignition system uses individual ignition coil/module assemblies for each cylinder. The engine control module (ECM) controls the individual coils by transmitting timing pulses on the ignition control (IC) circuit of each ignition coil/module to enable a spark event. Each ignition coil/module has the following circuits

1. An ignition voltage circuit
2. A ground circuit
3. An IC control circuit
4. A low reference circuit

Schematic Reference

Engine Controls Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

1. «Circuit Testing»(/cadillac/sts/i-2007-2011/remont/body-electrical/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__circuit-testing)
2. «Connector Repairs»(/cadillac/sts/i-2007-2011/remont/body-electrical/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__connector-repairs)
3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/sts/i-2007-2011/remont/body-electrical/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__testing-for-intermittent-conditions-and-poor)
4. «Wiring Repairs»(/cadillac/sts/i-2007-2011/remont/body-electrical/#wiring-systems-and-power-management-service-troubleshooting-diagnosis__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Special Tools

J 26792 HEI Spark Tester

Observe the Engine Controls Schematic for the ignition coils/modules, and review the Ignition System Specifications to verify the following

1. The ignition coil/modules are correctly connected
2. The proper firing order
3. The proper spark plug type
4. The proper spark plug gap and torque-Refer to «Ignition System Specifications»(/cadillac/sts/i-2007-2011/remont/testing-diagnostics/#engine-controls-and-fuel-46l-introduction__ignition-system-specifications) .

1. Turn OFF the ignition.
2. Inspect the fuse that supplies voltage to the ignition coil/modules. If the fuse is open, then test the spliced circuits and the individual ignition coil/modules for a short to ground.
3. Disconnect the affected ignition coil/module.
4. Connect a test lamp between the ignition coil/module ignition 1 voltage circuit terminal A and a good ground.
5. Turn ON the ignition.
6. With the test lamp still connected, measure for battery voltage between the ignition 1 voltage circuit and a good ground. If the voltage is not within 1 volt of battery voltage, repair the high resistance or the open in the ignition 1 voltage circuit.
7. Turn OFF the ignition, and all electrical accessories. Allow sufficient time for all of the control modules to power down before taking a resistance measurement.
8. Measure for a proper value of less than 5 ohms between the ground circuit terminal D of the affected ignition coil/module and a good ground. If the resistance is more than 5 ohms, repair the high resistance or the open in the ground circuit.
9. Exchange the affected ignition coil/module with the ignition coil/module of a good cylinder.
10. Start the engine and observe the scan tool. If the misfire transfers with the suspect ignition coil/module, replace as needed. If the misfire does not transfer with the suspect ignition coil/module, observe the component testing procedures below, and replace the spark plug if needed.

1. Use the Spark Plug Inspection procedure to verify the integrity of the spark plugs. Refer to «Spark Plug Inspection»(/cadillac/sts/i-2007-2011/remont/testing-diagnostics/#engine-controls-and-fuel-44l-introduction) .
2. Use the J 26792 to verify the output of each ignition coil/module.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

1. «Ignition Coil Replacement - Bank 1»(/cadillac/sts/i-2007-2011/remont/testing-diagnostics/#engine-controls-and-fuel-46l-introduction)
2. «Ignition Coil Replacement - Bank 2»(/cadillac/sts/i-2007-2011/remont/testing-diagnostics/#engine-controls-and-fuel-46l-introduction)
3. «Spark Plug Replacement»(/cadillac/sts/i-2007-2011/remont/testing-diagnostics/#engine-controls-and-fuel-46l-introduction)

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/sts/i-2007-2011/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/sts/i-2007-2011/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/sts/i-2007-2011/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Description

Several states require that a vehicle pass on-board diagnostic (OBD) system tests and the inspection/maintenance (I/M) emission inspection in order to renew vehicle registration. 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 composing 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

1. The vehicle is new from the factory and has not yet been driven through the necessary drive conditions to complete the tests.
2. The battery has been disconnected or discharged below operating voltage.
3. The control module power or ground has been interrupted.
4. The control module has been reprogrammed.
5. The control module DTCs have been cleared.

Monitored Emission Control Systems

The OBD II System monitors all emission control systems that are on-board. The OBD II regulations require monitoring of the following

1. The air conditioning system
2. The catalytic converter efficiency
3. Comprehensive component monitoring-Emission related inputs and outputs
4. The evaporative emission (EVAP) system
5. The fuel delivery system
6. Heated catalyst monitoring
7. Misfire monitoring
8. The oxygen sensor system (O2S or HO2S)
9. The oxygen sensor heater system (HO2S heater)
10. 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.

Review the I/M System Status indicators. All I/M System Status indicators should report YES.

1. Observe the Engine DTC information with a scan tool. If a DTC is set that would prevent the I/M System Status tests from completing, diagnose that DTC before continuing. Refer to «Inspection/Maintenance (I/M) System DTC Table»(/cadillac/sts/i-2007-2011/remont/testing-diagnostics/#engine-controls-and-fuel-46l-troubleshooting-diagnosis) .
2. Review applicable service bulletins for software updates that would prevent the I/M System Status tests from completing. If a control module re-program or other repair is required, perform the «Inspection/Maintenance (I/M) Complete System Set Procedure»(/cadillac/sts/i-2007-2011/remont/testing-diagnostics/#engine-controls-and-fuel-46l-troubleshooting-diagnosis) .
3. Observe the I/M System Status indicators. If any I/M System Status indicators report NO, perform the «Inspection/Maintenance (I/M) Complete System Set Procedure»(/cadillac/sts/i-2007-2011/remont/testing-diagnostics/#engine-controls-and-fuel-46l-troubleshooting-diagnosis) .

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/sts/i-2007-2011/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/sts/i-2007-2011/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/sts/i-2007-2011/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

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 I/M monitored diagnostic tests are completed, the I/M system status indicators are set to YES. Perform the I/M complete system set procedure if any I/M system status indicators are set to NO.

Conditions for Meeting a Cold Start

1. The ignition voltage between 11-18 volts.
2. The barometric pressure (BARO) is more than 75 kPa.
3. The start-up engine coolant temperature (ECT) is between 4-30°C (39-86°F).
4. The start-up intake air temperature (IAT) is between 4-30°C (39-86°F).
5. The difference between the IAT and the ECT is 6°C (10.8°F).
6. The ambient air temperature is between 4-30°C (39-86°F).
7. Fuel level is between 15-85 percent.
8. Vehicle has NOT been refueled since the last cold start ignition cycle

Review the Inspection/Maintenance (I/M) System Status indicators. All I/M System Status indicators should report YES.

Inspection/Maintenance (I/M) System Set Procedure

1. Ensure that the vehicle meets the conditions for a cold start listed above. If the EVAP I/M System Status indicator displays NO, perform the EVAP Service bay test if applicable. If the EVAP Service bay test is NOT available, it may take up to 6 drive cycles, with 17 hours between drive cycles for the EVAP I/M System Status Indicator to transition to YES. The EVAP I/M System Status indicator requires several drive and 17 hour key OFF cycles to complete before the indicator will transition. If the O2S Heater System Status indicator displays NO, ensure that the ignition has been turned OFF for at least 10 hours.
2. Turn OFF all accessories; HVAC system, other electrical loads, including aftermarket/add-on equipment, etc., and open the hood.
3. Set the vehicle parking brake and ensure the vehicle is in park for automatic transmission or neutral for manual transmission.
4. Turn the ignition ON with the engine OFF for 1 minute.
5. Start and idle the engine for 2 minutes and until 65°C (149°F) is achieved.
6. Run the engine for 6.5 minutes within the following conditions: MAF parameter between 4-30 g/s Engine speed steady between 1,000-3,000 RPM
7. Return the engine to idle for 1 minute.
8. Apply and hold brake pedal, and shift to Drive for automatic, or apply clutch pedal for manual and operate the vehicle within the following conditions for 2 minutes: Depress the accelerator pedal until TP Sensor angle is more than 2 percent. MAF signal between 15-30 g/s RPM steady between 1,200-2,000 RPM
9. Release the accelerator pedal and shift the vehicle to Park for automatic, or Neutral and release clutch pedal for manual, and allow the engine to idle for 2 minutes.
10. Quickly depress the accelerator pedal until TP Sensor Angle is more than 8 percent and return to idle, repeat 3 times.
11. Allow engine to idle for at least 2 minutes.
12. Close the hood, release the parking brake and drive vehicle at 24 km/h (15 mph) or slower for 2 minutes.
13. Continue to drive the vehicle for at least 5.5 miles between 45-112 km/h (28-70 mph) with the vehicle reaching at least 80 km/h (50 mph).
14. Release the accelerator pedal for at least 3 seconds. This will allow the vehicle to enter the decel fuel cut off. Repeat 4 more times.
15. Depress the accelerator pedal until the TP Sensor angle is between 3-20 percent and maintain for 1 minute.
16. Safely stop the vehicle, with the engine in drive for automatic or neutral with the clutch pedal depressed and parking brake applied for manual. Allow the vehicle to idle for 2 minutes.
17. Shift the vehicle to park for automatic and neutral for manual. Turn OFF the ignition and exit the vehicle. Do NOT disturb the vehicle for 45 minutes.
18. Observe the Inspection/Maintenance (I/M) System Status with a scan tool. All of the I/M System Status indicators should display YES. If the EVAP I/M System Status indicator displays NO turn OFF the ignition for 17 hours, ensure that the vehicle meets the conditions for a cold start, and repeat steps 13-18 three more times, or until the EVAP I/M System Status indicator transitions to YES. If the indicator continues to display NO, refer to the «Inspection/Maintenance (I/M) System DTC Table»(/cadillac/sts/i-2007-2011/remont/testing-diagnostics/#engine-controls-and-fuel-46l-troubleshooting-diagnosis) to identify the DTCs that did not run.

1. If any of the I/M System Status indicators display NO, refer to the «Inspection/Maintenance (I/M) System DTC Table»(/cadillac/sts/i-2007-2011/remont/testing-diagnostics/#engine-controls-and-fuel-46l-troubleshooting-diagnosis) for the indicator which did not display YES. The I/M System DTC Table identifies the DTCs associated with each I/M System Status Indicator.

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/sts/i-2007-2011/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/sts/i-2007-2011/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/sts/i-2007-2011/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/sts/i-2007-2011/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2) prior to using this diagnostic procedure.
2. Review «Strategy Based Diagnosis»(/cadillac/sts/i-2007-2011/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2__strategy-based-diagnosis) for an overview of the diagnostic approach.
3. «Diagnostic Procedure Instructions»(/cadillac/sts/i-2007-2011/remont/oem-general-information/#vehicle-diagnostic-information-2-of-2__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The purpose of the evaporative emission (EVAP) Service Bay Test is to aid in resetting the EVAP inspection/maintenance (I/M) system status. For this vehicle that is equipped with the engine off natural vacuum (EONV) diagnostic, the Service Bay Test uses the scan tool to initiate the engine control module (ECM) regular sequence of EVAP system DTC tests, but with different enable criteria. By using the Service Bay Test the I/M indicator can be set without the need for multiple cold soaks.

The scan tool displays for the Service Bay Test are based on the events that occur within the following three categories

1. The engine running portion of the tests-The vehicle must remain at rest, in Park, or in Neutral, during this portion of the test. This test inspects for large leaks, a leaking purge valve and/or vent system restrictions. The scan tool will display test progress or the reason for an abort or failure.
2. Drive cycle-The scan tool will display time and distance needed to warm the fuel.
3. Ignition OFF-During this portion of the test, the engine controller will remain active for up to 45 minutes when the ignition is turned OFF to allow control of the EVAP vent valve and run the EONV test. The engine controller inspects for small leaks during this period by monitoring fuel tank pressure or vacuum. If the system is sealed, there will be a pressure or vacuum change. Pressure or vacuum changes that are less than the calibrated values indicate a leak.

When the EVAP diagnostics are initiated by the Service Bay Test, the scan tool will indicate if the enable conditions listed below are not met, or will display a specific reason if the test aborts. When complete, the display will indicate that the tests passed or failed.

Conditions for Running the Test

The following conditions must be met in order to enable the Service Bay Test

1. The battery voltage is between 11-18 volts.
2. The engine coolant temperature (ECT) is less than 70°C (158°F) at start-up.
3. The EVAP I/M system status indicator is set to NO.
4. The fuel level is 15-85 percent capacity and cannot be refueled during the tests.
5. There are no DTCs displayed.
6. The vehicle must be driven for the time and distance specified on the scan tool.
7. The ambient air temperature is between 0-40°C (32-104°F).
8. The ignition must remain OFF during the engine OFF portion of the test, and the vehicle must remain at rest.

Test Procedure

Note. If the Service Bay Test aborts or fails a DTC will NOT be set.

1. Install a scan tool.
2. Select the Service Bay Test with the scan tool.
3. Follow the instructions on the scan tool. If the test aborts, correct the condition for running the test and then retest. If the test fails, repair the vehicle for the condition indicated by the failure message on the scan tool.
4. Verify that the EVAP I/M system status is set to YES.

See also:
• Diagnostic System Check - Vehicle
• Strategy Based Diagnosis
• Diagnostic Procedure Instructions
• Control Module References
• Component Connector End Views
• Evaporative Emissions Hose Routing Diagram
• Alcohol/Contaminants-in-Fuel Diagnosis
• Ignition System Specifications
• DTC P0171, P0172, P0174, or P0175
• Symptoms - Engine Exhaust
• Throttle Body Inspection and Cleaning
• Symptoms - Engine Cooling
• Symptoms - Engine Mechanical
• Temperature Versus Resistance
• Symptoms - Engine Electrical
• Crankshaft and Bearing Cleaning and Inspection
• Engine Controls Schematics
• Instrument Cluster Schematics
• Circuit Testing
• Connector Repairs
• Testing for Intermittent Conditions and Poor Connections
• Wiring Repairs
• Diagnostic Repair Verification
• Battery Inspection/Test
• Engine Cranks Slowly
• Starting System Description and Operation
• Diagnostic Trouble Code (DTC) List - Vehicle
• Altitude Versus Barometric Pressure
• Restricted Exhaust
• Engine Compression Test
• Fuel Pressure Relief (Without CH 48027)
• Road Test Warning
• DTC P0420 or P0430
• Fuel System Diagnosis
• AFIT Test Procedure
• Fuel Injector Balance Test-Fuel Pressure Test
• Fuel Injector Balance Test with Special Tool
• Fuel Injector Balance Test with Tech 2
• Pressure Drop Calculation
• Particulate Contaminants in Fuel Testing Procedure
• Alcohol in Fuel Testing with Special Tool