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Engine Control System & Fuel System - Hybrid (hp2) 6.0l (lz1) - Troubleshooting & Diagnosis Cadillac Escalade GMT900

Testing & Diagnostics ~10321 words

Diagnostic Instructions

  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provide an overview of each diagnostic category.

Symptoms Description

Symptoms cover conditions that are not covered DTCs. Certain conditions can cause multiple symptoms. These conditions are listed together under Symptoms Testing. Conditions that may only cause certain symptoms are listed separately under Additional Symptoms Test. Perform the Symptoms Testing before using the Additional Symptoms Tests. Poor Fuel Fill Quality test may be performed separately from the Symptoms Testing and Additional Symptoms Tests procedures.

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 DTCs that are stored.
  3. Ensure that the scan tool data is within a normal operating range.
  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 «Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs) .
  2. Ensure that the vacuum hoses are not split, kinked, and properly connected, as shown on the Vehicle Emission Control Information label.
  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 for the following conditions: The fuel system for the following: Correct fuel pressure-Refer to «Fuel System Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-hybrid-hp2-60l-lz1-troubleshooting-diagnosis) . Fuel injectors that are leaking or improper operation-Refer to «Fuel Injector Diagnosis (CH 47976)»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-hybrid-hp2-60l-lz1-troubleshooting-diagnosis) or «Fuel Injector Diagnosis (J 39021 or Tech 2)»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-hybrid-hp2-60l-lz1-troubleshooting-diagnosis) . Contaminated or a poor fuel quality condition-Refer to «Alcohol/Contaminants-in-Fuel Diagnosis (Without Special Tool)»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-53l-60l-62l-troubleshooting-diagnosis) or «Alcohol/Contaminants-in-Fuel Diagnosis (Special Tool)»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-53l-60l-62l-troubleshooting-diagnosis) . The ignition system for the following: Spark plugs for incorrect heat range or an abnormal condition-Refer to «Spark Plug Inspection»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-53l-60l-62l-repair-instructions__spark-plug-inspection) . For diagnosis of coolant or oil fouled spark plugs, refer to «Loss of Coolant»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system__loss-of-coolant) or «Symptoms - Engine Mechanical»(/cadillac/escalade/gmt900-2006-2014/remont/mechanical/#engine-mechanical-hybrid-hp2-60l-lz1) . Wet down the secondary ignition system with water from a spray bottle. Wetting down the secondary ignition system may help locate damaged or deteriorated components. Look/listen for arcing or misfiring as the water is applied. Weak spark using the J 26792 Spark Tester-Refer to «Electronic Ignition System Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-hybrid-hp2-60l-lz1-troubleshooting-diagnosis) . The operation of the transmission torque converter clutch (TCC)-The scan tool should indicate an engine speed drop when the TCC is commanded ON. The operation of the A/C compressor Items that can cause an engine to run rich or lean. Inspect the heated oxygen sensors (HO2S). The HO2S should respond quickly to different throttle positions. CAUTION: Refer to «Heated Oxygen and Oxygen Sensor Caution»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#dangers-warnings-and-cautions__heated-oxygen-and-oxygen-sensor-caution) . Water intrusion in the HO2S connector The cylinder deactivation system. Refer to «Cylinder Deactivation (Active Fuel Management) System Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-hybrid-hp2-60l-lz1-troubleshooting-diagnosis) . NOTE: The embossed arrows on the MAF sensor indicate the direction of the intake air flow. The arrows must point toward the engine. Inspect the MAF sensor installation. A MAF sensor that is incorrectly installed may cause a hard start. Install the MAF in the proper direction. Refer to «Mass Airflow Sensor with Intake Air Temperature Sensor Replacement»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-53l-60l-62l-repair-instructions) . Inspect the MAF sensor connections. Engine oil contaminated by fuel The engine for the following mechanical failures-Refer to «Symptoms - Engine Mechanical»(/cadillac/escalade/gmt900-2006-2014/remont/mechanical/#engine-mechanical-hybrid-hp2-60l-lz1) : Excessive oil in the combustion chamber or leaking valve seals 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 Vacuum hoses for splits or kinks-Verify that the routing and connections are as shown on the Vehicle Emission Control Information label. Knock sensor (KS) system for excessive spark retard activity-Refer to «DTC P0324, P0325, P0326, P0327, P0328, P0330, P0332, or P0333»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-hybrid-hp2-60l-lz1-dtc-p0315-to-dtc-p1255p064a) . The exhaust system components for the following: Physical damage or possible internal failure The three-way catalytic converters for a restriction For more information, refer to «Symptoms - Engine Exhaust»(/cadillac/escalade/gmt900-2006-2014/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-Refer to «Crankcase Ventilation System Inspection/Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/mechanical/#engine-mechanical-53l-60l-62l-diagnostic-information-and-procedures__crankcase-ventilation-system-inspectiondiagnosis) . Evaporative emission (EVAP) canister purge solenoid that is stuck open The engine cooling system for the following conditions: The thermostat is the correct heat range. Refer to «Thermostat Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system) . Proper engine coolant level-Refer to «Cooling System Draining and Filling (Static Fill)»(/cadillac/escalade/gmt900-2006-2014/remont/cooling-system-mechanical/#engine-cooling-system__cooling-system-draining-and-filling-static) .
  2. If the above conditions do not address the symptom, refer to the additional symptoms tests.

Additional Symptoms Tests

Hard Start

  1. Hood position switch is open
  2. Test the engine coolant temperature (ECT) sensor. Compare the ECT sensor value to the intake air temperature (IAT) sensor value on a cold engine. The ECT and IAT sensor values should be within ± 3°C (5°F). If the ECT sensor is out of range with the IAT sensor, test the resistance of the ECT sensor. Refer to «Temperature Versus Resistance»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-53l-60l-62l-specifications__temperature-versus-resistance) for resistance specifications. Replace the ECT sensor if the resistance is not within specification. Refer to «Engine Coolant Temperature Sensor Replacement»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-hybrid-hp2-60l-lz1-repair-instructions) . If the sensor is within the specification, test the ECT circuits for a high resistance.
  3. Test the idle air control (IAC) system.
  4. Test the fuel system operation. The fuel pump should turn ON for 2 seconds when the ignition is turned ON and have the correct fuel pressure. Refer to «Fuel System Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-hybrid-hp2-60l-lz1-troubleshooting-diagnosis) .

Hesitation, Sag, Stumble

  1. Test the manifold absolute pressure (MAP) sensor. Refer to «DTC P0106»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-hybrid-hp2-60l-lz1-dtc-p0010-to-dtc-p0308) .
  2. Test the generator. Refer to «Symptoms - Engine Electrical»(/cadillac/escalade/gmt900-2006-2014/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.

Poor Fuel Economy

  1. Heavy loads being carried or towed.
  2. Acceleration rate too much or too often.
  3. 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.

Poor Fuel Fill Quality

Test for the following conditions that is applicable to the current symptom.

Difficult to Fill

  1. Restricted vent lines
  2. The evaporative emission (EVAP) vent valve is stuck closed
  3. High fuel temperature
  4. A condition with the internal components of the fuel tank assembly. For more information, refer to
  5. «Fuel System Description»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-hybrid-hp2-60l-lz1-description-and-operation)
  6. «Evaporative Emission Control System Description»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-53l-60l-62l-description-and-operation)

Fuel Odor

  1. Saturated EVAP canister-Refer to «Evaporative Emission Control System Description»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-53l-60l-62l-description-and-operation) .
  2. A condition with the internal components of the fuel tank assembly-Refer to «Fuel System Description»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-hybrid-hp2-60l-lz1-description-and-operation) .
  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Circuit/System Description

Ignition voltage is supplied to the malfunction indicator lamp (MIL). The engine control module (ECM) turns the MIL ON by grounding the MIL control circuit.

Reference Information

Schematic Reference

  1. «Instrument Cluster Schematics»(/cadillac/escalade/gmt900-2006-2014/remont/gauges-instrument-panels/#instrument-panel-system-displays-gauges)
  2. «Engine Controls Schematics»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-hybrid-hp2-60l-lz1-wiring-schematic-and-emission-hose-routing-diagrams)

Connector End View Reference

Electrical Information Reference

  1. «Circuit Testing»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__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.
  2. Engine idling, command the MIL ON and OFF with a scan tool while observing the following control circuit status parameters: MIL Circuit Short to Gnd Test Status MIL Circuit Open Test Status MIL Circuit Short to Voltage Test Status Each parameter should toggle between OK and Not Run or Not Run and OK.

Circuit/System Testing

  1. Ignition OFF, open the hood to disable the Auto-Stop function. Refer to «Hybrid Modes of Operation Description»(/cadillac/escalade/gmt900-2006-2014/remont/engine-control-systems/#hybrid-engine-controls-description-and-operation__hybrid-modes-of-operation-description) .
  2. Ignition ON, verify the scan tool hood position parameter displays Open. If the hood position does not display Open, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) for DTC P254F.
  3. Ignition ON, verify that the instrument panel cluster (IPC) warning indicators are illuminated. If the IPC warning indicators are not illuminated, test the 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.
  4. Ignition OFF, disconnect harness connector X1 at the ECM.
  5. Ignition ON, verify the MIL is not illuminated. If the MIL is illuminated, test the MIL control circuit for a short to ground. If the circuit tests normal, replace the IPC.
  6. Connect a 3 A fused jumper wire between the MIL control circuit terminal 12-X1 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.
  7. If all circuits test normal, replace the ECM.

Repair Procedures

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Instrument Cluster Replacement (Except Cadillac)»(/cadillac/escalade/gmt900-2006-2014/remont/gauges-instrument-panels/#instrument-panel-system-displays-gauges) or «Instrument Cluster Replacement (Cadillac)»(/cadillac/escalade/gmt900-2006-2014/remont/gauges-instrument-panels/#instrument-panel-system-displays-gauges)
  2. «Control Module References»(/cadillac/escalade/gmt900-2006-2014/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/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

This Engine Cranks but Does Not Run diagnostic is an organized approach to identify a condition which causes the engine to crank but does not continue to run. This diagnostic directs the service technician to the appropriate system diagnosis. This diagnostic assumes the vehicle system voltage levels are adequate for starter motor operation. Refer to Battery Inspection/Test and Engine Cranks Slowly . The fuel level supply must be adequate, and the fuel quality must be able to sustain the combustion process.

Diagnostic Aids

  1. When disconnecting electrical connectors or removing fuses and relays from a fuse block, always inspect both mating electrical terminals for corrosion and terminal tightness.
  2. Use the J 35616 Connector Test Adapter Kit for any test that requires probing the underhood fuse block terminals, component wire harness terminals, or the ECM wire harness terminals. See «Special Tools»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-hybrid-hp2-60l-lz1-special-tools-equipment) .

Schematic Reference

Connector End View Reference

Electrical Information Reference

  1. «Circuit Testing»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

DTC Type Reference

Scan Tool Reference

Control Module References for scan tool information

Special Tools

  1. J 34730-1A Fuel Pressure Gauge. See «Special Tools»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-hybrid-hp2-60l-lz1-special-tools-equipment) .
  2. J 35616-A/BT-8637 Connector Test Adapter Kit
  3. J 43244 Relay Puller Pliers

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

  1. If the vehicle passes the Circuit/System Verification test, refer to «Testing for Intermittent Conditions and Poor Connections»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor) .
  1. Ignition OFF, open the hood to disable the Auto Stop function. Refer to «Hybrid Modes of Operation Description»(/cadillac/escalade/gmt900-2006-2014/remont/engine-control-systems/#hybrid-engine-controls-description-and-operation__hybrid-modes-of-operation-description) .
  2. Ignition ON, verify the scan tool hood position parameter displays Open.
  3. Crank the engine while observing the scan tool Vehicle DTC Information. If any of the following DTCs are set, diagnose these DTCs first: DTC P0117, P0118, P0122, P0123, P0201-P0208, P0222, P0223, P0335, P0336, P0351-P0358, P0562, P0563, P0601-P0604, P0606, P0607, P062F, P0633, P0685, P0690, P1631, P1682, P16F3, or P2610. Refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) .
  4. With the ignition ON and the engine OFF, test the fuses that are supplied ignition 1 voltage by the powertrain relay. The test lamp should illuminate ON for each test point of the fuses. If the test lamp does not illuminate ON for at least one test point of each fuse, refer to «DTC P0685 or P0690»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-hybrid-hp2-60l-lz1-dtc-p0315-to-dtc-p1255p064a) .
  5. Crank the engine while observing the scan tool engine speed parameter. If engine RPM is not indicated, refer to «DTC P0335»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-hybrid-hp2-60l-lz1-dtc-p0315-to-dtc-p1255p064a) .
  6. Install a spark plug tester onto one ignition module/coil assembly on each bank of the engine.
  7. Crank the engine while observing both spark plug testers. Both spark plug testers should spark. If spark is not observed, is inconsistent, or weak on either spark plug tester, refer to «Electronic Ignition System Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-hybrid-hp2-60l-lz1-troubleshooting-diagnosis) .
  8. With the ignition ON and the engine OFF, command the fuel pump ON and OFF with the scan tool. The fuel pump should energize when commanded ON, and de-energize when commanded OFF. If the fuel pump does not turn ON and OFF, refer to «Fuel System Diagnosis (w/o FPCM)»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-53l-60l-62l-troubleshooting-diagnosis) or «Fuel System Diagnosis (FPCM)»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-53l-60l-62l-troubleshooting-diagnosis) .
  9. Turn OFF the ignition.
  10. Install the J 34730-1A Fuel Pressure Gauge. See «Special Tools»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-hybrid-hp2-60l-lz1-special-tools-equipment) . With the ignition ON and the engine OFF, command the fuel pump ON several times with the scan tool. Refer to «Fuel System Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-hybrid-hp2-60l-lz1-troubleshooting-diagnosis) for the fuel pressure specification.
  11. Inspect for the following conditions: Compare the actual engine coolant temperature to the ECT parameter. Filter and air intake system for restrictions and obstructions Test the fuel for contamination-Refer to «Alcohol/Contaminants-in-Fuel Diagnosis (Without Special Tool)»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-53l-60l-62l-troubleshooting-diagnosis) or «Alcohol/Contaminants-in-Fuel Diagnosis (Special Tool)»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-53l-60l-62l-troubleshooting-diagnosis) . Inspect the spark plugs-Refer to «Spark Plug Inspection»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-53l-60l-62l-repair-instructions__spark-plug-inspection) . Test the exhaust system for restrictions-Refer to «Restricted Exhaust»(/cadillac/escalade/gmt900-2006-2014/remont/exhaust/#engine-exhaust-system) . Engine mechanical conditions, such as worn timing chain, sprocket gears, low compression, etc.-Refer to «Symptoms - Engine Mechanical»(/cadillac/escalade/gmt900-2006-2014/remont/mechanical/#engine-mechanical-hybrid-hp2-60l-lz1) .

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

ProblemCauses
DEFINITION: During the fueling process a continual, occasional or no fuel nozzle shut-off condition has occurred.
Difficult to fillFuel fill limiter vent valve stuck closed Evaporative emission (EVAP) canister restricted EVAP vent valve stuck closed Hose between canister and canister vent solenoid twisted or kinked if applicable High fuel temperature Fuel filler hose is kinked Faulty dispensing nozzle Ignition switch ON, vent valve closed
Over fillFill limiter vent valve stuck open or leaking Fuel inlet check valve stuck open
Pre-mature shut-off of the fuel dispensing nozzle occurs immediately after engaging dispensing nozzle, tank emptyRestricted vapor lines or fuel fill pipe High fuel temperature Inlet check valve at tank stuck closed, fill pipe full of fuel Fuel tank full, gauge not accurate
Pre-mature shut-off of the fuel dispensing nozzle, more than 1/8 of tank capacity dispensedKinked, pinched or plugged lines in fuel tank vent system EVAP vent valve stuck closed or restricted EVAP canister restricted Fuel limiting vent valve stuck closed or obstruction at top of fuel tank
Fuel SpitbackRestricted EVAP canister High fuel temperature Ignition switch ON, EVAP vent valve closed
  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provide 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 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

Connector End View Reference

Electrical Information Reference

  1. «Circuit Testing»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Special Tools

CH-47976 Active Fuel Injector Tester

Component Testing

Fuel Injector Coil Test

  1. Ignition OFF, open the hood to disable the Auto-Stop function. Refer to «Hybrid Modes of Operation Description»(/cadillac/escalade/gmt900-2006-2014/remont/engine-control-systems/#hybrid-engine-controls-description-and-operation__hybrid-modes-of-operation-description) .
  2. Ignition ON, verify the scan tool hood position parameter displays Open. If the hood position does not display Open, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) for DTC P254F.
  3. Verify the resistance of each fuel injector with one of the following methods: 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 Active Fuel Injector Tester (AFIT) Test Procedure. If not within the specified range, replace the fuel injector.
  4. 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.
  1. If the difference is equal to or less than 3 ohms, refer to AFIT Test Procedure.
  2. 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 difference above or below the average.
IMPORTANTDO 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. Ignition OFF, open the hood to disable the Auto-Stop function. Refer to «Hybrid Modes of Operation Description»(/cadillac/escalade/gmt900-2006-2014/remont/engine-control-systems/#hybrid-engine-controls-description-and-operation__hybrid-modes-of-operation-description) .
  2. Ignition ON, verify the scan tool hood position parameter displays OPEN If the hood position does not display OPEN, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) for DTC P254F.
  3. Turn OFF all accessories.
  4. Turn OFF the ignition.
  5. Install the AFIT. Refer to the AFIT User Guide.
  6. Turn ON the AFIT and select the vehicle.
  7. 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 Injector Diagnosis (CH 47976)»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-hybrid-hp2-60l-lz1-troubleshooting-diagnosis) or «Fuel Injector Diagnosis (J 39021 or Tech 2)»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-hybrid-hp2-60l-lz1-troubleshooting-diagnosis) .
  8. View the test results. If any injector exceeds the recommended tolerance, replace the injector(s), E-85 only. All other engine, refer to «Fuel Injector Cleaning»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-53l-60l-62l-repair-instructions__fuel-injector-cleaning) .

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provide 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

Connector End View Reference

Electrical Information Reference

  1. «Circuit Testing»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

DTC Type Reference

Scan Tool Reference

Control Module References for scan tool information

Special Tools

  1. CH-48027 Digital Pressure Gauge
  2. J 39021 Fuel Injector Coil and Balance Tester. See «Special Tools»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-hybrid-hp2-60l-lz1-special-tools-equipment) .
  3. J 44602 Injector Test Adapter

Fuel Injector Coil Test

  1. Ignition OFF, open the hood to disable the Auto-Stop function. Refer to «Hybrid Modes of Operation Description»(/cadillac/escalade/gmt900-2006-2014/remont/engine-control-systems/#hybrid-engine-controls-description-and-operation__hybrid-modes-of-operation-description) .
  2. Ignition ON, verify the scan tool hood position parameter displays Open. If the hood position does not display Open, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) for DTC P254F.
  3. Verify the resistance of each fuel injector with one of the following methods: 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 Fuel Injector Balance Test - Fuel Pressure Test. If not within the specified range, replace the fuel injector.
  4. 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.
  1. If the difference is equal to or less than 3 ohms, refer to Fuel Injector Balance Test - Fuel Pressure Test for further diagnosis of the fuel injectors.
  2. If the difference is greater 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 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. Ignition OFF, install a CH-48027 fuel pressure gauge. Refer to «Fuel Pressure Gauge Installation and Removal»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-hybrid-hp2-60l-lz1-repair-instructions) .
  2. Ignition ON, command the fuel pump Enable ON with a scan tool. Verify the fuel pressure is within 365-414 kPa (53-60 psi). If not within the specified range, refer to «Fuel System Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-hybrid-hp2-60l-lz1-troubleshooting-diagnosis) for further diagnosis of the fuel system.
  3. Monitor the CH-48027 for one minute. The fuel pressure should not decrease greater than 34 kPa (5 psi). If the fuel pressure decreases greater than 34 kPa (5 psi), refer to «Fuel System Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-hybrid-hp2-60l-lz1-troubleshooting-diagnosis) .
  4. Perform the Fuel Injector Balance Test with Special Tool or the Fuel Injector Balance Test with Tech 2.

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 to a fuel injector with a J 44602 . See «Special Tools»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-hybrid-hp2-60l-lz1-special-tools-equipment) .
  3. Command the fuel pump Enable 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.
  4. Command the fuel pump Enable ON one more time and energize the fuel injector by depressing the Push to Start Test button on the J 39021 at the previously selected pressure. See «Special Tools»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-hybrid-hp2-60l-lz1-special-tools-equipment) .
  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.

Fuel Injector Balance Test with Tech 2

  1. Command the fuel pump Enable 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 and record the Min pressure.
  7. Clear the Min/Max results on the CH-48027 .
  8. Select Normal from the Display Mode on the CH-48027 .
  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.

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 greater 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, E-85 only. All other engine, refer to «Fuel Injector Cleaning»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-53l-60l-62l-repair-instructions__fuel-injector-cleaning) .

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

The engine control module (ECM) supplies a high voltage signal to the fuel pump control module (FPCM) when the ECM detects that the ignition is on. The high voltage signal from the ECM to the FPCM remains active for 2 seconds, unless the engine is in crank or run. While this signal is being received, the FPCM closes the ground switch of the fuel pump and also supplies a varying voltage to the fuel tank pump module in order to maintain the desired fuel rail pressure.

Electrical Information Reference

  1. «Circuit Testing»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Special Tools

  1. CH-48027 Fuel Pressure Gauge
  2. J 37287 Fuel Line Shut-Off Adapters
  1. Ignition OFF, open the hood to disable the Auto-Stop function. Refer to «Hybrid Modes of Operation Description»(/cadillac/escalade/gmt900-2006-2014/remont/engine-control-systems/#hybrid-engine-controls-description-and-operation__hybrid-modes-of-operation-description) .
  2. Ignition ON, verify the scan tool hood position parameter displays OPEN If the hood position does not display OPEN, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) for DTC P254F.
  3. Ignition OFF, all accessories OFF, install the CH-48027 . Refer to «Fuel Pressure Gauge Installation and Removal»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-hybrid-hp2-60l-lz1-repair-instructions) .
  4. Ignition ON, command the fuel pump Enable ON with a scan tool. Verify the fuel pressure is between 345-414 kPa (50-75 psi) and remains steady for 5 minutes.
  1. Ignition ON, command the fuel pump Enable ON with a scan tool and observe the fuel pressure gauge while the fuel pump is operating. Verify the fuel pressure is between 345-414 kPa (50-75 psi). If the fuel pressure is less than the specified range, remove the fuel tank and test, inspect, and repair the items listed below. If all items test normal, replace the fuel pump. Restricted fuel feed pipe 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 (Without CH 48027)»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-hybrid-hp2-60l-lz1-repair-instructions__fuel-pressure-relief-without-ch-48027) . Install the J 37287 between the fuel feed pipe and the fuel rail. Open the valve on the J 37287 . Ignition ON, command the fuel pump relay ON with a scan tool and bleed the air from the fuel pressure gauge. Close the valve on the J 37287 . Verify that the fuel pressure does not decrease more than 34 kPa (5 psi) in 1 minute. If the fuel pressure drops, locate and replace the leaking fuel injector. If the fuel system test normal, replace the fuel pump.
  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 fuel pump.
  4. Operate the vehicle within the conditions of the customer's concern while monitoring the fuel pressure with the CH-48027 . The fuel pressure should not drop off during accelerations, 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 fuel pump module.
  5. If the fuel system components test normal, refer to «Symptoms - Engine Controls»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-53l-60l-62l-troubleshooting-diagnosis) .

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Fuel Injector Replacement»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-hybrid-hp2-60l-lz1-repair-instructions)
  2. «Fuel Tank Fuel Pump Module Replacement»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-hybrid-hp2-60l-lz1-repair-instructions)

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.

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

IMPORTANTDo not perform this diagnostic procedure unless directed to do so by another diagnostic.

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.

  1. 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.
  2. 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.
  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

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.

  1. Using an approved fuel container, draw approximately 0.5 liter (0.13 gal) of fuel.
  2. 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.

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.

Test Procedure

IMPORTANTDo not perform this diagnostic procedure unless directed to do so by another diagnostic.
  1. Test the fuel composition using J 44175 Fuel Composition Tester and J44175-3 Instruction Manual.
  2. 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.
  3. If the fuel sample contains more than 15 percent ethanol, add fresh, regular gasoline to the vehicle's fuel tank.
  4. Test the fuel composition.
  5. If testing shows the ethanol percentage is still more than 15 percent, replace the fuel in the vehicle.
Frequency (Hz)Subtract 50Ethanol Percent
Example A50 Hz500
Example B65 Hz5015
Example C129 Hz5079

Fuel Composition Test Examples

  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

This ignition system uses individual ignition module/coil assemblies for each cylinder. The engine control module (ECM) controls the spark events by transmitting the timing pulses on the ignition control (IC) circuits to the individual ignition module/coil assemblies in firing order sequence.

Schematic Reference

Connector End View Reference

Electrical Information Reference

  1. «Circuit Testing»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

Control Module References for scan tool information

Special Tools

J 26792 Spark Plug Tester

  1. Ignition OFF, open the hood to disable the Auto-Stop function. Refer to «Hybrid Modes of Operation Description»(/cadillac/escalade/gmt900-2006-2014/remont/engine-control-systems/#hybrid-engine-controls-description-and-operation__hybrid-modes-of-operation-description) .
  2. Ignition ON, verify the scan tool hood position parameter displays Open. If the hood position does not display Open, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) for DTC P254F.
  1. Ignition OFF, open the hood to disable the Auto-Stop function. Refer to «Hybrid Modes of Operation Description»(/cadillac/escalade/gmt900-2006-2014/remont/engine-control-systems/#hybrid-engine-controls-description-and-operation__hybrid-modes-of-operation-description) .
  2. Ignition ON, verify the scan tool hood position parameter displays Open. If the hood position does not display Open, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) for DTC P254F.
  3. Ignition OFF for 1 minute, disconnect the harness connector at the ignition coil.
  4. Ignition OFF, all vehicle systems OFF, this may take up to 2 minutes, test for less than 5 ohms between the ground circuit terminal B and ground. If greater than the specified range, repair the ground circuit for an open/high resistance.
  5. Test for less than 5 ohms between the low reference circuit terminal C and ground. If greater than the specified range, test the circuit for an open/high resistance. If the circuit tests normal, replace the ECM.
  6. Test for less than 2 between the ignition voltage circuit terminal A and the fuse. If greater than the specified range, repair the ignition voltage circuit for high resistance.
  7. Ignition ON, verify that a test lamp illuminates between the ignition voltage circuit terminal A and ground. If the test lamp does not illuminate, test the ignition voltage circuit for a short to ground or an open/high resistance. If the circuit tests normal and the ignition voltage circuit fuse is open, test all components connected to the ignition voltage circuit and replace as necessary.
  8. If all circuits test normal, test or replace the ignition coil assembly.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. «Ignition Coil Replacement»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-hybrid-hp2-60l-lz1-repair-instructions)
  2. «Control Module References»(/cadillac/escalade/gmt900-2006-2014/remont/communication-devices/#programming-and-setup-all-systems__control-module-references) for ECM replacement, setup, and programming

Operating Instructions for the Evaporative Emission System Tester (EEST)

Vehicle Setup

  1. Engine OFF, open the hood. Position a large fan to blow air under the vehicle onto the fuel tank area.
  2. Connect the red battery clip from the tester to the positive battery terminal.
  3. Connect the black battery clip from the tester to chassis ground.

Flowmeter Test - Leak Detection

  1. Open the Nitrogen tank valve and turn the NITROGEN/SMOKE valve on the front control panel to NITROGEN.
  2. Connect the hose to the correct test orifice on the bottom front of the tester. For orifice size, refer to the GM Service manual for the vehicle being tested. The vehicle specific information can be found in service procedures for DTCs that relate to evaporative emission (EVAP) system leaks.
  3. Press and release the remote switch to activate the tester.
  4. Position the sliding red flag on the flowmeter to align with the floating indicator. When the red flag is set, press and release the remote switch to deactivate the tester.
  5. Remove the hose from the test orifice and install the hose onto the vehicle. For proper connection location, and the special tool numbers for any adapters that may be required, refer to the service procedures for DTCs that relate to EVAP system leaks.
  6. Ignition ON, seal the EVAP system per instructions in the service procedures for DTCs that relate to EVAP system leaks. Most systems can be sealed using a scan tool output control for the EVAP canister vent solenoid valve, other systems require that the vent system be plugged.
  7. Press and release the remote switch to activate the nitrogen flow and fill the system.
  8. Compare the stable floating indicator position to the red flag. ABOVE the red flag, the result is UNACCEPTABLE, FAIL-Go to «Smoke Procedure - Locate the Leak»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-hybrid-hp2-60l-lz1-troubleshooting-diagnosis__smoke-procedure-locate-the-leak) BELOW the red flag, the result is ACCEPTABLE, PASS-Test complete
  9. Press and release the remote switch to deactivate the tester.

Smoke Procedure - Locate the Leak

  1. Turn OFF any fans that may cause air movement around or near the vehicle.
  2. Connect the nitrogen/smoke hose to the vehicle as directed in the service procedures. Some vehicles require that the nitrogen/smoke hose be connected at the front of the EVAP system at the EVAP service port. An adapter may be necessary. Other vehicles require the connection be made at the rear of the system using an adapter at the fuel fill cap. Consult the service procedures for DTCs that relate to evaporative emission (EVAP) system leaks for vehicle specific instructions regarding connection location and adapters.
  3. Open the nitrogen tank valve and turn the NITROGEN/SMOKE valve on the control panel to SMOKE.
  4. Press and release the remote switch to activate the tester and inject smoke into the EVAP system.
  5. Verify smoke has filled the EVAP system by opening the system opposite the end where smoke is injected. When injecting smoke at the service port, remove the fuel fill cap, or temporarily leave the EVAP canister vent valve open, until smoke is observed. Then close the system and continue testing. If using a special tool fuel fill cap adapter at the filler neck, vent the system at the service port until smoke is observed then close the system to continue with the test.
  6. Press and release the remote switch to deactivate the tester.
  7. Introduce smoke into the system for an additional 60 seconds. Continue introducing smoke at 15-second intervals, as necessary.
  8. Using the a high-intensity white light, inspect the entire EVAP system path, and look for the source of the leak indicated by the exiting smoke. Introduce smoke at 15-second intervals, as needed, until leak source is identified.

The Concern

Ideal circumstances for conducting the EVAP Flowmeter Test require equal temperatures between the nitrogen gas and the vehicle EVAP system. Significant differences in temperature between them can result in a flow or pressure change during testing, causing misleading results. Typically, the Evaporative Emissions System Tester is stored indoors, approximately 21°C (70°F). Vehicles brought in for diagnosis may have an EVAP system at significantly different temperatures -40 to +43°C (-40 to +110°F).

For Example

Note. With no temperature difference between the nitrogen gas and EVAP system, the resulting vehicle EVAP system pressure will remain stable at 13 inches H2O once pressurized, providing no leaks are present.

When the EVAP Flowmeter Tests are performed with significant differences in temperature between the nitrogen gas and the vehicle EVAP system, the following results can occur

  1. An increase in flow during the flowmeter test can be caused by a vehicle's warm EVAP system cooling down.
  2. A decrease in flow during the flowmeter test can be caused by a vehicle's cool EVAP system warming up.

The Solution

When working on a vehicle with significant temperature differences between the vehicle EVAP system and the nitrogen gas, allow the vehicle EVAP system temperature to stabilize as close as possible to the temperature of the nitrogen gas before conducting the Flowmeter Test.

  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

Circuit Description

To provide maximum fuel economy under light load driving conditions, the engine control module (ECM) will command the valve lifter oil manifold (VLOM) solenoids ON, to deactivate engine cylinders 1 and 7 on the left bank, and cylinders 4 and 6 on the right bank. The VLOM consists of 4 electrically operated normally closed solenoids, which directs pressurized engine oil to 8 deactivating valve lifters. All 4 VLOM solenoids are connected in parallel to a fused ignition circuit supplied by the powertrain relay. The control circuit for each solenoid is connected to an individual low side driver internal to the ECM. When enabling conditions for V4 mode are met, the ECM will command each low side driver to turn ON, in engine firing order sequence.

The VLOM solenoids are assigned to the following engine cylinders

  1. Solenoid #1-Cylinder #1
  2. Solenoid #2-Cylinder #4
  3. Solenoid #3-Cylinder #6
  4. Solenoid #4-Cylinder #7

Schematic Reference

Connector End View Reference

Description and Operation

Electrical Information Reference

  1. «Circuit Testing»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__circuit-testing)
  2. «Connector Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__connector-repairs)
  3. «Testing for Intermittent Conditions and Poor Connections»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__testing-for-intermittent-conditions-and-poor)
  4. «Wiring Repairs»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__wiring-repairs)

Scan Tool Reference

  1. If any DTCs are set, then repair those DTC first. Refer to «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) .
  2. Start and idle the engine.
  3. Allow the engine to reach normal engine operating temperature. The engine should idle smoothly without any misfires. If the engine misfires, refer to «DTC P0300-P0308»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-hybrid-hp2-60l-lz1-dtc-p0010-to-dtc-p0308) .
  4. Monitor the cylinder deactivation system data parameters with a scan tool.
  5. Road test the vehicle under light throttle and load conditions that will allow the ECM to command V4 mode. If all enabling conditions are met for cylinder deactivation, and if no internal engine hydraulic/mechanical fault conditions are present, the ECM will continue operation in V4 mode. If the vehicle passes the Circuit/System Verification test, then review the active fuel management driving information in the Features and Controls section of the owners manual with the vehicle operator, or instruct the vehicle operator in the proper driving techniques to obtain V4 mode. If the vehicle does not pass the Circuit/System Verification test, then review the cylinder deactivation inhibit reasons listed on the scan tool.

Electrical System Testing

  1. Ignition OFF, open the hood to disable the Auto-Stop function. Refer to «Hybrid Modes of Operation Description»(/cadillac/escalade/gmt900-2006-2014/remont/engine-control-systems/#hybrid-engine-controls-description-and-operation__hybrid-modes-of-operation-description) .
  2. Ignition ON, verify the scan tool hood position parameter displays Open. If the hood position does not display Open, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) for DTC P254F.
  3. Ignition ON and the engine OFF, command each VLOM solenoid ON and OFF using the scan tool. Standing next to the engine compartment, you should be able to hear the solenoid energize and de-energize with each command.
  1. If you cannot hear each solenoid energize and de-energize, then refer to «DTC P3401, P3425, P3441, or P3449»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-hybrid-hp2-60l-lz1-dtc-p1380-to-dtc-p3449) .

Mechanical System Testing

  1. Ignition OFF, open the hood to disable the Auto-Stop function. Refer to «Hybrid Modes of Operation Description»(/cadillac/escalade/gmt900-2006-2014/remont/engine-control-systems/#hybrid-engine-controls-description-and-operation__hybrid-modes-of-operation-description) .
  2. Ignition ON, verify the scan tool hood position parameter displays Open. If the hood position does not display Open, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) for DTC P254F.
  3. Connect a vacuum gauge to the EVAP vacuum tube fitting on the electronic throttle body. DO NOT use a compound pressure and vacuum gauge. The vacuum gauge on a hand held vacuum pump will work fine for this test.
  4. Start the engine. Allow the engine to reach normal operation temperature.
  5. With a scan tool, command each VLOM solenoid ON, one at a time. Each time a solenoid is command ON, you should observe a fluctuating drop of intake manifold vacuum, and a misfire on the cylinder that was deactivated. If there is no fluctuating drop in engine vacuum, or the engine does not misfire, then refer to «Cylinder Deactivation (Active Fuel Management) System Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-hybrid-hp2-60l-lz1-troubleshooting-diagnosis) .

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-procedure-instructions) provides an overview of each diagnostic category.

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 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 complies with the local area requirements. While testing in the I/M System Status mode, some DTCs may occur that are called I/M Test DTCs. An I/M Test DTC is defined as a fault code that is currently commanding the MIL ON, and is stored in non-volatile memory. The intended use of this data is to prevent vehicles from passing I/M inspection without proper repair to the vehicle. These fault codes are not erasable from any scan tool command or erasable by disconnecting power to the controller. The I/M Test DTCs will be supported by all emissions related ECUs such as ECMs, TCMs, FPCMs, etc. An I/M Test DTC will not be stored or erased from the ECU except at the end of trip processing which occurs 5 s after ignition OFF.

Conditions for Updating the I/M System Status

Each system requires at least one, and sometimes several, diagnostic tests. The results of these tests are 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 any one of the DTCs comprising the monitor have illuminated the malfunction indicator lamp (MIL). Once all of the tests are completed, 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 as part of a service procedure.

Conditions for Clearing I/M Test DTCs

  1. Only the OBD II System can erase the I/M Test DTC. The OBD II system must determine that the malfunction that caused the I/M Test DTC to be stored is no longer present and is not commanding the MIL. Each of the following represents ways to clear an I/M Test DTC: If the MIL goes out due to 3 passing drive cycles, scan tool code clear is not used, the I/M Test DTC is erased at power down of the last drive cycle. If a scan tool code clear is used to turn OFF the MIL, the I/M Test DTC is not erased, the DTC must PASS and not FAIL. The I/M Test DTC is erased at power down of the drive cycle. If the controller is reflashed/reprogrammed, all I/M Test DTCs are erased.
  2. For the OBD II System to run a single drive cycle for clearing an I/M Test DTC, all of the following conditions must occur: Cumulative time of engine run time is greater than 600 s. Cumulative vehicle operation above 41 kPa (25 mph) for over 300 s. Continuous vehicle idle for greater than 30 s. Turn ignition OFF for 5 s and allow the code to clear.

Monitored Emission Control Systems

The OBD II system monitors all emission control systems that are on-board. Not all vehicles need every possible emission control system. 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; if equipped

  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)

For the specific DTCs required for each system, refer to Inspection/Maintenance System DTC Table . Systems such as 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.

The I/M System Status display provides an indication of when the control module has completed the required tests. This does not necessarily mean that the test has passed, only that a decision was made. If the diagnostic fails, a DTC will indicate the failure. If a failure indication is present for a DTC associated with one of the I/M regulated systems, it may prevent other required tests from running. For example, a DTC for the control circuit of the EVAP purge solenoid may not be listed in the Inspection/Maintenance System DTC Table because it is a continuous test. If this DTC is set, the Active Tests for the EVAP system may not run.

The I/M System Status information may be useful for a technician to determine if diagnostics have run when verifying repairs.

Review the I/M System Status indicators. All I/M System Status indicators should report YES, and no I/M Test DTCs should be present.

  1. Observe the Engine DTC information with a scan tool. Verify no DTCs are present. If a DTC is set that would prevent the I/M System Status tests from completing, diagnose that DTC before continuing. Refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) .
  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/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-hybrid-hp2-60l-lz1-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/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-hybrid-hp2-60l-lz1-troubleshooting-diagnosis) .
  4. Observe the I/M Test DTC information with a scan tool. Verify there are no I/M Test DTCs present. If an I/M Test DTC is set and all of the I/M System Status indicators are Yes, there is no need to perform the Complete System Set Procedure. Diagnose the DTC using the «Diagnostic Trouble Code (DTC) List - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) and refer to Conditions for Clearing the I/M Test DTCs. If an I/M Test DTC is set and the I/M System Status indicators are NO, diagnosis the DTC and perform the «Inspection/Maintenance (I/M) Complete System Set Procedure»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-hybrid-hp2-60l-lz1-troubleshooting-diagnosis) .
  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__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 Inspection/Maintenance (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 is between 10-15 V.
  2. The barometric pressure (BARO) is more than 75 kPa.
  3. The engine coolant temperature (ECT) at start-up is less than 42°C (108°F).
  4. The intake air temperature (IAT) is between 2-32°C (36-90°F).
  5. The engine is OFF for greater than 6 h or the following conditions must be met: The start-up IAT minus start-up ECT are within 12°C (22°F). The start-up ECT minus start-up IAT are within 50°C (90°F).
  6. Fuel level is between 25-75 %.

Review the Inspection/Maintenance (I/M) System Status indicators. All I/M System Status indicators should report YES, and no I/M Test DTCs should be present.

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.
  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. Start and idle the engine for 2 min.
  5. Close the hood, release the parking brake and Accelerate at part throttle to 72-80 km/h (45-50 mph) with this speed maintained until the engine reaches operating temperature, 8-10 min.
  6. Continue operation under these conditions for an additional 6 min.
  7. Accelerate at part throttle to 90 km/h (55 mph) with this speed maintained for 2 min.
  8. Release the accelerator pedal for at least 10 s. This will allow the vehicle to enter the decel fuel cut off.
  9. 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 min.
  10. 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 min.
  11. 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, ensure that the vehicle meets the conditions for a cold start, and repeat steps 6-11 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 System DTC Table»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-hybrid-hp2-60l-lz1-troubleshooting-diagnosis__inspectionmaintenance-system-dtc-table) to identify the DTCs that did not run. If any of the I/M System Status indicators display NO, refer to the «Inspection/Maintenance System DTC Table»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-hybrid-hp2-60l-lz1-troubleshooting-diagnosis__inspectionmaintenance-system-dtc-table) 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.
  12. Observe the I/M Test DTC information with a scan tool. Verify there are no I/M Test DTCs present. If an I/M Test DTC is set, diagnose the DTC using the «Diagnostic Trouble Code (DTC) List - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) and refer to «Inspection/Maintenance System Check»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-hybrid-hp2-60l-lz1-troubleshooting-diagnosis) .
  13. Observe the engine DTC information with a scan tool. Verify no DTCs are present. If a DTC is set, diagnose using the «Diagnostic Trouble Code (DTC) List - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) . After repairs, perform the «Inspection/Maintenance (I/M) Complete System Set Procedure»(/cadillac/escalade/gmt900-2006-2014/remont/testing-diagnostics/#engine-control-system-fuel-system-hybrid-hp2-60l-lz1-troubleshooting-diagnosis) to verify no further DTCs are set.

Inspection/Maintenance System DTC Table

SystemDTCs Required to Set System Status to YES
If an I/M System Status indicator did NOT update to YES during the Inspection/Maintenance (I/M) Complete System Set Procedure , review each indicator and reference this table to determine each DTC associated with the I/M System Status Indicator. Each DTC listed below has specific conditions that must be met for the diagnostic to run. Included within the conditions are additional DTCs which, if set, may inhibit the DTCs listed below from running. Reviewing and operating the vehicle within the Conditions for Running for each DTC listed below will allow the I/M System Status Indicators to transition to YES.
CatalystDTC P0420 or P0430
EVAPDTC P0442 DTC P0446 DTC P0451-P0454 DTC P0455
Oxygen SensorDTC P0496 DTC P0133, P013A-P013F, P014A, P014B, P0153, P1133, or P1153 DTC P0134, P0140, P0154, or P0160 DTC P2270 or P2272 DTC P2271 or P2273
Oxygen Sensor HeaterDTC P0030, P0036, P0050, P0053, P0054, P0056, P0059, P0060, P0135, P0141, P0155, or P0161
Camshaft SystemDTC P0011
  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) prior to using this diagnostic procedure.
  2. Review «Strategy Based Diagnosis»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__strategy-based-diagnosis) for an overview of the diagnostic approach.
  3. «Diagnostic Procedure Instructions»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__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.

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

  1. Ignition OFF, open the hood to disable the Auto-Stop function. Refer to «Hybrid Modes of Operation Description»(/cadillac/escalade/gmt900-2006-2014/remont/engine-control-systems/#hybrid-engine-controls-description-and-operation__hybrid-modes-of-operation-description) .
  2. Ignition ON, verify the scan tool hood position parameter displays Open. If the hood position does not display Open, refer to «Diagnostic Trouble Code (DTC) List - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures__diagnostic-trouble-code-dtc-list) for DTC P254F.
  3. Select the Service Bay Test with the scan tool.
  4. 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.
  5. Verify that the EVAP I/M system status is set to YES.

See also:
• Diagnostic System Check - Vehicle
• Strategy Based Diagnosis
• Diagnostic Procedure Instructions
• Wiring Repairs
• Alcohol/Contaminants-in-Fuel Diagnosis (Without Special Tool)
• Spark Plug Inspection
• Loss of Coolant
• Symptoms - Engine Mechanical
• Heated Oxygen and Oxygen Sensor Caution
• Mass Airflow Sensor with Intake Air Temperature Sensor Replacement
• DTC P0324, P0325, P0326, P0327, P0328, P0330, P0332, or P0333
• Symptoms - Engine Exhaust
• Crankcase Ventilation System Inspection/Diagnosis
• Thermostat Diagnosis
• Cooling System Draining and Filling (Static Fill)
• Temperature Versus Resistance
• Engine Coolant Temperature Sensor Replacement
• DTC P0106
• Symptoms - Engine Electrical
• Fuel System Description
• Evaporative Emission Control System Description
• Instrument Cluster Schematics
• Engine Controls Schematics
• Component Connector End Views
• Circuit Testing
• Connector Repairs
• Testing for Intermittent Conditions and Poor Connections
• Control Module References
• Hybrid Modes of Operation Description
• Diagnostic Trouble Code (DTC) List - Vehicle
• Diagnostic Repair Verification
• Battery Inspection/Test
• Engine Cranks Slowly
• Special Tools
• Restricted Exhaust
• Fuel Injector Cleaning
• Fuel Pressure Relief (Without CH 48027)
• Engine Control Module Scan Tool Information (V8 Gasoline)
• DTC P3401, P3425, P3441, or P3449
• Road Test Warning
• Fuel System Diagnosis
• Smoke Procedure - Locate the Leak
• Inspection/Maintenance System DTC Table

More articles — Engine Performance