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Hybrid Engine Controls - Symptom Troubleshooting & Diagnosis Cadillac Escalade GMT900

Engine Control Systems ~3651 words

Symptoms - Hybrid Controls

IMPORTANTThe following steps must be completed before using the symptom tables.
  1. Perform the «Diagnostic System Check - Vehicle»(/cadillac/escalade/gmt900-2006-2014/remont/oem-general-information/#vehicle-diagnostic-information-diagnostic-information-and-procedures) before using the symptom tables in order to verify that all of the following are true: There are no DTCs set. The control modules can communicate via the serial data link.
  2. Review the system operation in order to familiarize yourself with the system functions. Refer to the following procedures: «Drive Motor Generator Control Module Description and Operation»(/cadillac/escalade/gmt900-2006-2014/remont/engine-control-systems/#hybrid-engine-controls-description-and-operation) «High Voltage Monitoring Systems Description»(/cadillac/escalade/gmt900-2006-2014/remont/engine-control-systems/#hybrid-engine-controls-description-and-operation__high-voltage-monitoring-systems-description) «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) «Drive Motor Battery System Description»(/cadillac/escalade/gmt900-2006-2014/remont/charging-system/#hybrid-energy-storage-system) «Transmission General Description»(/cadillac/escalade/gmt900-2006-2014/remont/automatic-trans/#automatic-transmission-2ml70-description-and-operation__transmission-general-description)

Visual/Physical Inspection

  1. Inspect for aftermarket devices which could affect the operation of the Hybrid System. Refer to «Checking Aftermarket Accessories»(/cadillac/escalade/gmt900-2006-2014/remont/ignition-switchsteering-lock/#wiring-systems-and-power-management-diagnostic-information-and-procedures__checking-aftermarket-accessories) .
  2. Inspect the easily accessible or visible system components for obvious damage or conditions which could cause the symptom.

Intermittent

Faulty electrical connections or wiring may be the cause of intermittent conditions. Refer to Testing for Intermittent Conditions and Poor Connections .

Symptom List

Refer to a symptom diagnostic procedure from the following list in order to diagnose the symptom

  1. «Engine Will Not Crank»(/cadillac/escalade/gmt900-2006-2014/remont/engine-control-systems/#hybrid-engine-controls-symptom-troubleshooting-diagnosis)
  2. «Engine Does Not AutoStop»(/cadillac/escalade/gmt900-2006-2014/remont/engine-control-systems/#hybrid-engine-controls-symptom-troubleshooting-diagnosis)

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) provides an overview of each diagnostic category.

Circuit/System Description

This vehicle does not use a 12V starter motor to crank the internal combustion engine (ICE). A much more powerful 300V motor generator located within the transmission is utilized to crank the engine. The 300V motor generator can rotate the engine to operating speed, 800 RPM, within just a few hundred milliseconds. The 300V motor generator allows near-instant starting of the engine.

The body control module (BCM) monitors the position of the ignition switch. When the ignition switch is placed in the Crank position, the BCM sends out a Crank-Request message over GMLAN. The hybrid powertrain control module (HPCM) responds to this GMLAN message by applying torque to drive motor generator 1 located within the transmission. Drive motor generator 1 is mechanically linked to the engine crankshaft.

The HPCM will not respond to the BCM Crank-Request GMLAN message if certain vehicle conditions exist such as the transmission gear selector position does not equal Park or Neutral or certain DTCs are set.

Circuit/System Verification

  1. Ensure the range selector lever is in Park or Neutral.
  2. Turn the ignition key to crank.
  3. The engine should instantly crank and run. If the engine starts and runs, the system is operating normally.

Circuit/System Testing

  1. Verify no HPCM or engine control module (ECM) DTCs are set that would disable high voltage or that identify a gear selector switch concern. If the specified DTCs are set, repair them first. 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. Observe the BECM Contactor System Status parameter. You should observe contactor status as Closed. If the parameter displays Precharge Inhibit, the BECM is operating in the precharge resistor protection mode and high voltage has been disabled for 35 minutes. Observe the BECM Precharge Wait Time parameter to determine the amount of disable time remaining. Turn the ignition OFF and wait the applicable amount of time before attempting to crank the engine.
  3. Observe the HPCM IMS Range parameter display with a scan tool. The display should indicate Park or Neutral. If the display does not indicate Park or Neutral, adjust the range selector lever cable. Refer to «Range Selector Lever Cable Adjustment»(/cadillac/escalade/gmt900-2006-2014/remont/automatic-trans/#automatic-transmission-2ml70-repair-instructions-on-vehicle__range-selector-lever-cable-adjustment) .
  4. Verify that serial data gateway module (SDGM) DTC B009F is not set. If B009F is set, refer to «DTC B009F»(/cadillac/escalade/gmt900-2006-2014/remont/engine-control-systems/#hybrid-engine-controls-dtc-b008a-to-dtc-p0af7) .
  5. Observe the SDGM Hybrid Crash Status parameter. If the vehicle has not been involved in a collision the parameter should display No Crash. If the parameter displays Crash Detected and/or the vehicle has been involved in a collision the high voltage system should be inspected for damage before the high voltage system is re-enabled. Refer to «High Voltage System Inspection»(/cadillac/escalade/gmt900-2006-2014/remont/engine-control-systems/#hybrid-engine-controls-repair-instructions) .
  6. Verify the vehicle has not been in a collision that resulted in supplemental inflatable restrain (SIR) deployment. If SIR deployment has occurred the high voltage system should be inspected for damage before the high voltage system is re-enabled. Refer to «High Voltage System Inspection»(/cadillac/escalade/gmt900-2006-2014/remont/engine-control-systems/#hybrid-engine-controls-repair-instructions) .
  7. Observe the BECM Hybrid Battery Pack Calculated voltage parameter with a scan tool. You should observe greater than 305 volts. If the hybrid battery voltage is less than the specified value, attempt to charge the Hybrid Battery. Refer to «Jump Assist»(/cadillac/escalade/gmt900-2006-2014/remont/charging-system/#hybrid-energy-storage-system) .
  8. Observe the BECM Hybrid Battery SOC parameter with a scan tool. You should observe greater than 20 % hybrid battery state of charge. If the hybrid battery SOC is the same or less than the specified value, attempt to charge the Hybrid Battery. Refer to «Jump Assist»(/cadillac/escalade/gmt900-2006-2014/remont/charging-system/#hybrid-energy-storage-system) .
  9. Turn the ignition to Crank. The engine should instantly start and run. If the engine does not crank but audible transmission noise is observed while cranking, inspect the transmission for internal component failure. A seized engine or accessory drive could cause transmission damage during engine crank. If the engine does not crank and no audible transmission noise is observed, continue with diagnosis.
  10. Perform the HPCM scan tool Clear 300V Impact Detection DTC output control. Turn the ignition OFF for 60 seconds.
  11. Turn the ignition to Crank. The engine should instantly start and run. If the engine cranks, the DTC Information for SDGM DTC B009F had been previously cleared without performing the scan tool output control. Ensure DTC B009F runs and passes. If the engine does not crank, continue with diagnosis.
  12. Perform the HPCM scan tool Clear 300V Present DTC output control. Turn the ignition OFF for 5 minutes.
  13. Turn the ignition to Crank. The engine should instantly start and run. If the engine cranks, the DTC Information for DTC P0C76 had been previously cleared without performing the scan tool output control. Ensure DTC P0C76 runs and passes. If the engine does not crank, replace the drive motor generator power inverter module (PIM).

Repair Procedures

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for PIM 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.

Typical Scan Tool Data

Parameter DisplayAutostop Inhibit or Autostart Reason
4WD LowTransfer case selector is in 4 wheel drive Low Range
Autostart/stop OverrideScan tool Output Control active
Aux. Trans. Pump With ECM Ambient Air Temperature less than 10°C (50°F) 1DTC P0C2B or P2797 set OR ECM Ambient Air Temperature less than 10°C (50°F) 1
Aux. Trans. Pump With ECM Ambient Air Temperature 10°C (50°F) - 15°C (59°F) 1DTC P0C2B or P2797 set OR TFT less than 35°C (95°F) or greater than 95°C (203°F)
Aux. Trans. Pump With ECM Ambient Air Temperature 15°C (59°F) - 20° (68°F) 1DTC P0C2B or P2797 set OR TFT less than 25°C (77°F) or greater than 95°C (203°F)
Aux. Trans. Pump With ECM Ambient Air Temperature greater than 20° (68°F) 1DTC P0C2B or P2797 set TFT less than 20°C (68°F) or greater than 95°C (203°F)
Battery Pack TempHybrid Batt Min Cell Temp is less than 10°C (50°F) OR Hybrid Batt Max Cell Temp is Greater than 47°C (116°F)
Drvr Axle Torque RequestDepression of the accelerator pedal has exceeded the torque capability for electric-only or EV Mode propulsion
ECM RequestECM DTC testing in progress or ECM DTCs present
ECT - High LimitECT 110°C (230°F) or greater Autostop if cools down to 90°C (194°F) once high temperature limit has been reached.
ECT - Low Limit With ECM Ambient Air Temperature 10°C (50°F) - 20°C (68°F) 1ECT less than 68°C (154°F) Autostart if cools down to 60°C (140°F) once high temperature limit has been reached
ECT - Low Limit With ECM Ambient Air Temperature greater than 20°C (68°F) 1ECT less than 49°C (120°F) Autostart if cools down to 44°C (111°F)
Hood PositionOpen or faulted
Hybrid Batt. Pack Voltage250V or less When Autostop limit has been achieved, Autostart if voltage drops to 200V
Hybrid Batt. Pack Power15kW or less Power is dependent upon battery temperature. Observe Hybrid Battery Temperature parameters when Hybrid Batt. Pack Power inhibits Autostop. When Autostop limit has been achieved, Autostart if power drops to 12kW
Hybrid Battery SOC50% or less When Autostop limit has been achieved, Autostart if SOC drops to 46%
ICE Run Time With ECM Ambient Air Temperature 10°C (50°F) - 15°C (59°F) 1Less than 20 seconds since ignition crank
ICE Run Time With ECM Ambient Air Temperature greater than 15°C (59°F) 1Less than 5 seconds since ignition crank
Ignition CrankIgnition key not in RUN - engine remote started
IMS RangeGear Selector in Reverse or Manual
Invalid SignalThe HPCM has monitored invalid data and has stored a DTC
Inverter TemperatureGreater than 65°C (149°F) When Autostop limit has been achieved, Autostart at 70°C (158°F)
Min. Hybrid Batt. Module VoltageThe minimum hybrid battery module pair voltage is less than 14 volts. When Autostop limit has been achieved, Autostart if voltage drops to 12V.
Motor TemperatureGreater than 165°C (329°F) When Autostop limit has been achieved, Autostart at 170°C (338°F)
Operating ConditionsThe current driving conditions inhibit autostop operation. This parameter should be displayed along with other inhibit reasons such as Drvr Axle Torque Request
Reduced Engine PowerThe ECM is limiting engine torque output and has stored a DTC
Remote Start RequestThe vehicle has been started by remote transmitter
Reverse Inhibit CommandThe transmission gear selector has been placed in the Reverse position
Run/Crank ModeSDGM Power mode is not in RUN
System Voltage12V system voltage is out of range as monitored by the HPCM
Vehicle SpeedVehicle speed is greater than allowed
1 The HPCM monitors the ECM Ambient Air Temperature parameter to determine outside temperature. the ECM will default to 0°C (32°F) ambient air temperature if an IAT sensor DTC is present.

Autostop Inhibit Reasons

This vehicle does not use a 12V starter motor to crank the internal combustion engine (ICE). A much more powerful 300V motor/generator located within the transmission is utilized to crank the engine. The 300V motor/generator can rotate the engine to operating speed, 800 RPM, within just a few hundred milliseconds. The 300V motor/generator allows near-instant starting of the engine. Once started, engine operation may cycle between Autostop, engine off, and Autostart, engine running, for the duration of the drive trip.

Autostop/Autostart

The Two-Mode Hybrid vehicle does not require ICE operation at all times. After a successful engine start, the hybrid powertrain control module (HPCM) may turn off the engine, or Autostop, when not required for the current vehicle conditions. The engine will remain off while in Autostop mode, until such time that vehicle conditions require the engine to run. The near-instant starting of the engine from Autostop mode is called Autostart.

Autostop Conditions

Numerous conditions must all be within acceptable limits in order for the HPCM to allow the Autostop hybrid mode. The Typical Scan Tool Data information lists the vehicle conditions required for Autostop operation.

Diagnostic Aids

A chime will sound if the drivers door is opened while in Autostop as a reminder that the engine is not in the OFF mode.

Engine OFF and AUTO STOP modes are indicated on the tachometer display.

  1. When the tachometer needle indicates OFF, the engine is not running and will remain Off until the ignition key is placed in the Crank position or a remote vehicle start request is received from the keyless entry transmitter. Autostop is not allowed with a remote vehicle start.
  2. When the tachometer needle indicates AUTO STOP, the engine is not running but may Autostart at any time without notice.

Reference Information

DTC Type Reference

  1. Hood closed, start the engine with the ignition key and allow to idle.
  2. Monitor engine operation and the tachometer display for 5 minutes.
  3. The vehicle should enter the Autostop hybrid mode. If the vehicle operates in the Autostop hybrid mode, the system is operating normally. If the vehicle cycles rapidly in and out of the Autostop hybrid mode, test the auxiliary transmission fluid pump pressure. Refer to «Line Pressure Check»(/cadillac/escalade/gmt900-2006-2014/remont/automatic-trans/#automatic-transmission-2ml70-symptom-troubleshooting-diagnosis__line-pressure-check) . If the vehicle does not operate in the Autostop hybrid mode, continue to Circuit/System Testing.
  1. Verify no HPCM or ECM DTCs are set. Repair any HPCM or ECM DTCs prior to performing this diagnostic procedure.
  2. Engine at idle, observe the HPCM Autostop Inhibit Reasons scan tool parameter.
  3. Compare the parameter display to the Typical Scan Tool Data information.
  4. Identify which Autostop inhibit conditions have prohibited Autostop operation. An Inhibit condition will display YES on the scan tool.
  5. Determine if the Autostop inhibit conditions are the result of normal operating conditions or the result of a fault condition. Repair the conditions that are the result of a fault condition. For example, a hood switch that indicates hood status as open when the hood is actually closed. Advise the vehicle operator of the normal operating and environmental conditions that will inhibit Autostop. For example, advise that Autostop is disabled when hybrid Battery Pack temperature is less than 10°C (50°F).

Special Tools

EL-48458 Pre-Charge Tester. See Special Tools .

Description and Operation

The EL-48458 pre-charge tester is a device designed to assist in the diagnosis of fault conditions that may be difficult to differentiate between in the drive motor generator battery and the power inverter module (PIM). See Special Tools . The internal workings of the pre-charge tester include high voltage bulk capacitors to simulate the capacitance of the PIM. In addition, there are electronic components designed to mimic the redundant contactor pulse width modulated (PWM) command circuit in order to facilitate the closing and opening of the drive motor generator battery contactors without a PIM. The pre-charge tester also incorporates High Voltage Circuit LED indicators to alert the operator of the presence of high voltage to encourage safe operation.

The EL-48458 may be connected to the vehicle at either the PIM high voltage connection or at the drive motor generator battery high voltage terminal connection depending upon service information procedures. See Special Tools .

Installation Procedure When Testing at the PIM

  1. Ignition OFF, perform the «High Voltage Disabling»(/cadillac/escalade/gmt900-2006-2014/remont/charging-system/#hybrid-energy-storage-system__high-voltage-disabling) procedure for servicing at the drive motor generator control module assembly.
  2. Disconnect and remove the ACCM high voltage cables from the high voltage distribution box.
  3. Disconnect and remove the drive motor generator battery high voltage cables from the high voltage distribution box. Remove and retain the cable mounting block O-ring. Re-install the O-ring after testing is complete.
  4. Connect the drive motor generator battery high voltage cable assembly to the EL-48458 . See «Special Tools»(/cadillac/escalade/gmt900-2006-2014/remont/engine-control-systems/#hybrid-engine-controls-special-tools-equipment) . Ensure that the high voltage terminal cover on the EL-48458 is closed after connecting the high voltage cable assembly. See «Special Tools»(/cadillac/escalade/gmt900-2006-2014/remont/engine-control-systems/#hybrid-engine-controls-special-tools-equipment) .
  5. Place the EL-48458 contactor duty cycle switch in the Open Position. See «Special Tools»(/cadillac/escalade/gmt900-2006-2014/remont/engine-control-systems/#hybrid-engine-controls-special-tools-equipment) .
  6. Remove the drive motor generator control module sight shield HVIC connector from the PIM mounting block.
  7. Disconnect the 56-way connector from the PIM and connect the vehicle harness side connector to the EL-48458 . See «Special Tools»(/cadillac/escalade/gmt900-2006-2014/remont/engine-control-systems/#hybrid-engine-controls-special-tools-equipment) .
  8. Connect the EL-48458 HVIC connector to the drive motor generator control module sight shield HVIC connector. See «Special Tools»(/cadillac/escalade/gmt900-2006-2014/remont/engine-control-systems/#hybrid-engine-controls-special-tools-equipment) .
  9. Connect the alligator clip on the EL-48458 to a 12-volt vehicle chassis ground point. See «Special Tools»(/cadillac/escalade/gmt900-2006-2014/remont/engine-control-systems/#hybrid-engine-controls-special-tools-equipment) .
  10. Install the high voltage manual disconnect lever.
  11. Connect the 12-volt battery.
  12. Turn the Ignition Key to RUN. The Ignition ON LED on the EL-48458 should illuminate. See «Special Tools»(/cadillac/escalade/gmt900-2006-2014/remont/engine-control-systems/#hybrid-engine-controls-special-tools-equipment) . If the Ignition ON LED does not illuminate, verify the alligator clip connection to ground, then remove the 56-way connector and confirm with a DMM that the 12 volt ignition circuit is supplying the proper voltage to PIM connector X1 terminal 9 when the ignition key is in RUN. If 12 V battery voltage is measured at PIM connector X1 terminal 9 then the EL-48458 is not functioning and must be replaced. See «Special Tools»(/cadillac/escalade/gmt900-2006-2014/remont/engine-control-systems/#hybrid-engine-controls-special-tools-equipment) .
  13. Perform any tests and/or diagnostics as needed.

Removal Procedure When Testing at the PIM

  1. Move the EL-48458 High Voltage Contactor Relay switch to the Open Position. See «Special Tools»(/cadillac/escalade/gmt900-2006-2014/remont/engine-control-systems/#hybrid-engine-controls-special-tools-equipment) .
  2. The high voltage stored within the EL-48458 internal capacitors should begin to discharge. See «Special Tools»(/cadillac/escalade/gmt900-2006-2014/remont/engine-control-systems/#hybrid-engine-controls-special-tools-equipment) . After about 20 seconds. the HI VOLTAGE CIRCUIT indicator LEDs should operate in the following manner: The Greater Than 60 Volts When Lit LED should turn OFF. The Less Than 60 Volts When Lit LED should briefly illuminate. The Less Than 60 Volts When Lit LED should turn OFF.
  3. Turn the Ignition Key to OFF.
  4. Disconnect the 56-Way connector from the EL-48458 and the alligator clip from the ground connection. See «Special Tools»(/cadillac/escalade/gmt900-2006-2014/remont/engine-control-systems/#hybrid-engine-controls-special-tools-equipment) . Leave the high voltage terminal cover closed.
  5. Disconnect the EL-48458 high voltage interlock circuit (HVIC) connector from the drive motor generator control module sight shield HVIC connector. See «Special Tools»(/cadillac/escalade/gmt900-2006-2014/remont/engine-control-systems/#hybrid-engine-controls-special-tools-equipment) .
  6. Wait 5 minutes.
  7. Perform the high voltage disabling procedure. Refer to «High Voltage Disabling»(/cadillac/escalade/gmt900-2006-2014/remont/charging-system/#hybrid-energy-storage-system__high-voltage-disabling) .
  8. While still wearing your personal protection equipment, open the EL-48458 high voltage terminal cover and measure the high voltage terminal connections with a DMM using the following procedure: See «Special Tools»(/cadillac/escalade/gmt900-2006-2014/remont/engine-control-systems/#hybrid-engine-controls-special-tools-equipment) . Set the voltmeter to DC mode. Verify the voltmeter works by measuring the voltage of the 12-volt battery. Using the voltmeter, verify the voltage measures less than 3 volts across the HVDC (+) positive and HVDC (-) negative terminals. If the test result was more than 3 volts, the EL-48458 internal capacitors are still charged. See «Special Tools»(/cadillac/escalade/gmt900-2006-2014/remont/engine-control-systems/#hybrid-engine-controls-special-tools-equipment) . Keep the isolation gloves on and install the high voltage terminal cover. Wait 5 minutes and then remove the cover and return to the beginning of this step.
  9. When voltage is no longer present, disconnect the high voltage cables from the EL-48458 and remove the tool from the vehicle. See «Special Tools»(/cadillac/escalade/gmt900-2006-2014/remont/engine-control-systems/#hybrid-engine-controls-special-tools-equipment) .
  10. Re-assemble the vehicle as instructed in the diagnostic procedure.

Installation Procedure When Testing at the Drive Motor Generator Battery Assembly

  1. Ignition OFF, perform the «High Voltage Disabling»(/cadillac/escalade/gmt900-2006-2014/remont/charging-system/#hybrid-energy-storage-system__high-voltage-disabling) procedure for servicing at the drive motor generator battery assembly or 300V DC cables.
  2. Remove the 300V DC cables from the drive motor generator battery assembly.
  3. Attach the EL-48458 high voltage jumper to the drive motor generator battery high voltage terminals. See «Special Tools»(/cadillac/escalade/gmt900-2006-2014/remont/engine-control-systems/#hybrid-engine-controls-special-tools-equipment) . Ensure proper polarity connection by connecting the orange and black stripe wire to the negative terminal.
  4. Install the terminal extension cover assembly with the fasteners. Tighten the fasteners finger-tight.
  5. Insert the high voltage jumper connector into the EL-48458 . See «Special Tools»(/cadillac/escalade/gmt900-2006-2014/remont/engine-control-systems/#hybrid-engine-controls-special-tools-equipment) . Ensure that the high voltage terminal cover on the EL-48458 remains closed. See «Special Tools»(/cadillac/escalade/gmt900-2006-2014/remont/engine-control-systems/#hybrid-engine-controls-special-tools-equipment) .
  6. Place the EL-48458 contactor duty cycle switch in the Open Position. See «Special Tools»(/cadillac/escalade/gmt900-2006-2014/remont/engine-control-systems/#hybrid-engine-controls-special-tools-equipment) .
  7. Remove the 56-way connector from the PIM and connect the vehicle harness side connector to the EL-48458 . See «Special Tools»(/cadillac/escalade/gmt900-2006-2014/remont/engine-control-systems/#hybrid-engine-controls-special-tools-equipment) .
  8. Remove the drive motor generator control module sight shield HVIC connector from the PIM mounting block.
  9. Connect the EL-48458 HVIC connector to the drive motor generator control module sight shield HVIC connector. See «Special Tools»(/cadillac/escalade/gmt900-2006-2014/remont/engine-control-systems/#hybrid-engine-controls-special-tools-equipment) .
  10. Connect the alligator clip on the EL-48458 to a 12-volt vehicle chassis ground point. See «Special Tools»(/cadillac/escalade/gmt900-2006-2014/remont/engine-control-systems/#hybrid-engine-controls-special-tools-equipment) .
  11. Install the high voltage manual disconnect lever.
  12. Connect the 12-volt battery.
  13. Turn the Ignition Key to RUN. The Ignition ON LED on the EL-48458 should illuminate. See «Special Tools»(/cadillac/escalade/gmt900-2006-2014/remont/engine-control-systems/#hybrid-engine-controls-special-tools-equipment) . If the Ignition ON LED does not illuminate, verify the alligator clip connection to ground, then remove the 56-way connector and confirm with a DMM that the 12 volt ignition circuit is supplying the proper voltage to PIM connector X1 terminal 9 when the ignition key is in RUN. If 12 V battery voltage is measured at PIM connector X1 terminal 9 then the EL-48458 is not functioning and must be replaced. See «Special Tools»(/cadillac/escalade/gmt900-2006-2014/remont/engine-control-systems/#hybrid-engine-controls-special-tools-equipment) .
  14. Perform any tests and/or diagnostics as identified by the service information procedure.

Removal Procedure When Testing at the Drive Motor Generator Battery Assembly

  1. Move the EL-48458 High Voltage Contactor Relay switch to the Open Position. See «Special Tools»(/cadillac/escalade/gmt900-2006-2014/remont/engine-control-systems/#hybrid-engine-controls-special-tools-equipment) .
  2. The high voltage stored within the EL-48458 internal capacitors should begin to discharge. See «Special Tools»(/cadillac/escalade/gmt900-2006-2014/remont/engine-control-systems/#hybrid-engine-controls-special-tools-equipment) . After about 20 seconds. the HI VOLTAGE CIRCUIT indicator LEDs should operate in the following manner: The Greater Than 60 Volts When Lit LED should turn OFF. The Less Than 60 Volts When Lit LED should briefly illuminate. The Less Than 60 Volts When Lit LED should turn OFF.
  3. Turn the Ignition Key to OFF.
  4. Disconnect the 56-Way connector from the EL-48458 and the alligator clip from the ground connection. See «Special Tools»(/cadillac/escalade/gmt900-2006-2014/remont/engine-control-systems/#hybrid-engine-controls-special-tools-equipment) . Leave the high voltage terminal cover closed.
  5. Disconnect the EL-48458 high voltage interlock circuit (HVIC) connector from the drive motor generator control module sight shield HVIC connector. See «Special Tools»(/cadillac/escalade/gmt900-2006-2014/remont/engine-control-systems/#hybrid-engine-controls-special-tools-equipment) .
  6. Wait 5 minutes.
  7. Perform the high voltage disabling procedure. Refer to «High Voltage Disabling»(/cadillac/escalade/gmt900-2006-2014/remont/charging-system/#hybrid-energy-storage-system__high-voltage-disabling) .
  8. While still wearing your personal protection equipment, open the EL-48458 high voltage terminal cover and measure the high voltage terminal connections with a DMM using the following procedure: See «Special Tools»(/cadillac/escalade/gmt900-2006-2014/remont/engine-control-systems/#hybrid-engine-controls-special-tools-equipment) . Set the voltmeter to DC mode. Verify the voltmeter works by measuring the voltage of the 12-volt battery. Using the voltmeter, verify the voltage measures less than 3 volts across the HVDC (+) positive and HVDC (-) negative terminals. If the test result was more than 3 volts, the EL-48458 internal capacitors are still charged. See «Special Tools»(/cadillac/escalade/gmt900-2006-2014/remont/engine-control-systems/#hybrid-engine-controls-special-tools-equipment) . Keep the isolation gloves on and install the high voltage terminal cover. Wait 5 minutes and then remove the cover and return to the beginning of this step.
  9. When voltage is no longer present, disconnect the high voltage cables from the EL-48458 and remove the tool from the vehicle. See «Special Tools»(/cadillac/escalade/gmt900-2006-2014/remont/engine-control-systems/#hybrid-engine-controls-special-tools-equipment) .
  10. Remove the terminal extension cover and the EL-48458 high voltage jumper from the drive motor generator battery assembly. See «Special Tools»(/cadillac/escalade/gmt900-2006-2014/remont/engine-control-systems/#hybrid-engine-controls-special-tools-equipment) .
  11. Re-assemble the vehicle as instructed in 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 accessory power module (APM) supplies the energy that flows between the high voltage (300 volt) direct current (DC) and low voltage (14 volt) DC to charge the 12 volt battery and power accessories. The APM receives a wake-up signal on a discrete line from the serial data gateway module (SDGM) when the key is turned to RUN. After a successful engine start, the APM receives an enable command from the hybrid powertrain control module (HPCM) over the high speed hybrid GMLAN communication circuit to begin power conversion.

A poor connection at the B+ terminal of the APM or blown 200 Amp Mega-Fuse in the hybrid BEC will prevent the APM from powering up and all values in the APM data list will read zero on the scan tool.

A poor connection on the APM wake-up signal X1 Terminal 3 from the SDGM will also prevent the APM from powering up and all data values in the APM data list will read zero on the scan tool.

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. «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)

DTC Type Reference

Engine ON, observe the charge indicator on the instrument panel cluster (IPC) or message in the driver information center (DIC). The charge indicator on the IPC should be turned OFF and the DIC should not display charging system message.

  1. If the charge indicator is not on the IPC or a charging system message is not displayed on the DIC, 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) .
  2. If the charge indicator is on the IPC or a charging system message is displayed on the DIC, refer to «Circuit/System Testing»(/cadillac/escalade/gmt900-2006-2014/remont/engine-control-systems/#hybrid-engine-controls-symptom-troubleshooting-diagnosis) .
  1. Ignition ON, verify that no generator or battery current sensor DTCs are set that would cause a charging system concern. If DTCs are set, 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. Ignition OFF, measure the voltage across the battery terminals. The voltage should read 12.0 volts or greater at room temperature. If not within specified value, refer to «Battery Inspection/Test»(/cadillac/escalade/gmt900-2006-2014/remont/charging-system/#hybrid-engine-electrical-system-hp2) .
  3. Connect a carbon pile tester to the battery.
  4. Start the engine and turn all accessories off. Observe the voltage reading on the tester. The voltage should read between 12.6-15.5 volts.
  5. Adjust the carbon pile tester so that the 12 volt current on the APM data list is reading 175 amps. If not within specified value, replace the APM.

Perform the Diagnostic Repair Verification after completing the diagnostic procedure.

Control Module References for APM replacement, setup and programming.

See also:
• Diagnostic System Check - Vehicle
• Drive Motor Generator Control Module Description and Operation
• High Voltage Monitoring Systems Description
• Hybrid Modes of Operation Description
• Drive Motor Battery System Description
• Transmission General Description
• Checking Aftermarket Accessories
• Testing for Intermittent Conditions and Poor Connections
• Strategy Based Diagnosis
• Diagnostic Procedure Instructions
• Diagnostic Trouble Code (DTC) List - Vehicle
• Range Selector Lever Cable Adjustment
• DTC B009F
• High Voltage System Inspection
• Diagnostic Repair Verification
• Control Module References
• Line Pressure Check
• Special Tools
• High Voltage Disabling
• Hybrid Controls Schematics
• Component Connector End Views
• Circuit Testing
• Battery Inspection/Test
• Engine Will Not Crank

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