Test Description
The numbers below refer to the step numbers on the diagnostic table.
- 2: Listen for an audible click when the starter relay operates. Press the ignition switch back and forth from the ON to START positions. Repeat this as necessary.
- 3: This step tests for voltage at the coil side of the starter relay. The STARTER RLY fuse supplies power to the coil side of the starter relay.
- 4: This step verifies that the ECM is providing ground to the starter relay.
- 5: This step tests if ground is constantly being applied to the starter relay.
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Starting and Charging Schematics Connector End View Reference: Power and Grounding Connector End Views in Wiring Systems | |||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
| 2 | Install a scan tool. Turn ON the ignition, with the engine OFF. Press the ignition back and forth from the ON to START positions. Does the starter relay click with each command? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 |
| 3 | Turn OFF the ignition. Disconnect the starter relay. Turn ON the ignition, with the engine OFF. Probe the starter relay coil supply voltage circuit of the starter relay with a test lamp that is connected to a good ground. Does the test lamp illuminate? | Go to Step 4 | Go to Step 8 |
| 4 | Connect a test lamp between the starter relay control circuit and the starter relay coil supply voltage circuit of the starter relay. Turn the ignition back and forth from the ON to START positions. Does the test lamp turn ON and OFF with each command? | Go to Step 6 | Go to Step 5 |
| 5 | Test the control circuit of the starter relay for a short to voltage or an open. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 11 | Go to Step 7 |
| 6 | Inspect for poor connections at the starter relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 11 | Go to Step 9 |
| 7 | Inspect for poor connections at the engine control module (ECM). Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 11 | Go to Step 10 |
| 8 | Repair the battery positive voltage circuit of the starter relay. Refer to Connector Repairs in Wiring Systems. Did you complete the repair? | Go to Step 11 | |
| 9 | Replace the starter relay. Did you complete the replacement? | Go to Step 11 | |
| 10 | Replace the ECM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | Go to Step 11 | |
| 11 | Review and record the scan tool Failure Records data. Clear the DTCs. Operate the vehicle within the Failure Records conditions as noted. Using a scan tool, monitor the Specific DTC Information for DTC P0615. Does the scan tool indicate DTC P0615 failed this ignition? | Go to Step 2 | System OK |
DTC P0615
The number below refers to the step number on the diagnostic table.
- 5: A starter motor that remains engaged after engine start up can be cause by a starter relay that hangs up or a low current short to B+ on the starter solenoid crank voltage circuit. Verify the integrity of the starter solenoid crank voltage circuit before replacing the starter motor.
| Step | Action | Yes | No |
|---|---|---|---|
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
| 2 | Start the engine. Does the starter operate normally? | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3 |
| 3 | Start the engine while listening to the starter motor turn. Is there a loud "whoop", that may sound like a siren if the engine is revved while the starter is engaged, after the engine starts, but while the starter is still held in the engaged position? | Go to Step 6 | Go to Step 4 |
| 4 | Do you hear a "rumble", a "growl", or, in some cases, a "knock" as the starter is coasting down to a stop after starting the engine? | Go to Step 7 | Go to Step 5 |
| 5 | IMPORTANT: This is often diagnosed as a starter drive gear hang-in or a weak solenoid. When the engine is cranked, do you hear a high-pitched whine after the engine cranks and starts normally? | Go to Step 8 | Go to Step 7 |
| 6 | Inspect the flywheel ring gear for the following: Chipped gear teeth Missing gear teeth Milled teeth Is the flywheel bent, or does it have damaged teeth? | Go to Step 8 | Go to Step 7 |
| 7 | Remove the starter motor. Refer to Starter Motor Replacement (LY7) or Starter Motor Replacement (LH2) . Inspect the starter motor bushings and clutch gear. Does the clutch gear have chipped or milled teeth or worn bushings? | Go to Step 9 | Go to Step 10 |
| 8 | Replace the flywheel. Refer to Engine Flywheel Replacement in Engine Mechanical - 3.6L (LY7) or Engine Flywheel Replacement in Engine Mechanical - 4.6L (LH2). Did you complete the replacement? | Go to Step 10 | |
| 9 | Replace the starter motor. Refer to Starter Motor Replacement (LY7) or Starter Motor Replacement (LH2) . Did you complete the replacement? | Go to Step 10 | |
| 10 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 3 |
| IMPORTANT |
|---|
| This is often diagnosed as a starter drive gear hang-in or a weak solenoid. |
Starter Motor Noise Diagnosis
The numbers below refer to the step numbers on the diagnostic table.
- 1: The Diagnostic System Check - Vehicle must be performed or misdiagnosis will occur.
- 3: The remote start enable procedure is contained in the Starting System Description and Operation.
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Starting and Charging Schematics Connector End View Reference: Engine Electrical Connector End Views DEFINITION: The remote vehicle start function does not operate. | |||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle in Vehicle DTC Information |
| 2 | Press the lock button on the remote keyless entry fob. Do the vehicle doors lock? | Go to Step 3 | Go to Keyless Entry System Inoperative (Active) or Keyless Entry System Inoperative (Passive) in Keyless Entry |
| 3 | Turn ON the ignition, with the engine OFF. Enter the driver information center (DIC). Scroll the menu button until Remote Start appears on the display. Observe the DIC display. Does the DIC display ON? | Go to Starting System Description and Operation | Go to Step 4 |
| 4 | Install a scan tool. Observe the Remote Start Disable parameter in the instrument panel module (IPM), Remote Start Disable History Data list. Does the scan tool indicate that Ext. Crank is displayed? | Go to Engine Cranks but Does Not Run in Engine Controls - 3.6L or Engine Cranks but Does Not Run in Engine Controls - 4.6L | Go to Step 5 |
| 5 | Observe the Remote Start Disable in the IPM Remote Start Disable History Data list. Does the scan tool indicate that Battery Voltage is displayed? | Go to Battery Inspection/Test | Go to Step 6 |
| 6 | Observe the Remote Start Disable parameter. Does the scan tool indicate that Power Mode is displayed? | Go to Diagnostic Starting Point - Computer/Integrating Systems in Compute/Integrating Systems | Go to Step 7 |
| 7 | Inspect for poor connections at the harness connector of the IPM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 9 | Go to Step 8 |
| 8 | Replace the IPM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup, and programming. Did you complete the replacement? | Go to Step 9 | |
| 9 | Operate the system in order to verify the repair. Did you correct the condition? | System OK | Go to Step 4 |
Remote Start Does Not Work
Electrical Power Management (EPM) Overview
The electrical power management (EPM) system is designed to monitor and control the charging system and send diagnostic messages to alert the driver of possible problems with the battery and generator. This EPM system primarily utilizes existing on-board computer capability to maximize the effectiveness of the generator, to manage the load, improve battery state-of-charge and life, and minimize the system's impact on fuel economy. The EPM system performs 3 functions
- It monitors the battery voltage and estimates the battery condition.
- It takes corrective actions by boosting idle speeds, managing the loads, and adjusting the regulated voltage.
- It performs diagnostics and driver notification.
The battery condition is estimated during ignition-off and during ignition-on. During ignition-off the state-of-charge (SOC) of the battery is determined by measuring the open-circuit voltage. The SOC is a function of the acid concentration and the internal resistance of the battery, and is estimated by reading the battery open circuit voltage when the battery has been at rest for several hours.
The SOC can be used as a diagnostic tool to tell the customer or the dealer the condition of the battery. Throughout ignition-on, the algorithm continuously estimates SOC based on adjusted net amp hours, battery capacity, initial SOC, and temperature.
While running, the battery degree of discharge is primarily determined by a battery current sensor, which is integrated to obtain net amp hours.
In addition, the EPM function is designed to perform regulated voltage control (RVC) to improve battery SOC, battery life, and fuel economy. This is accomplished by using knowledge of the battery SOC and temperature to set the charging voltage to an optimum battery voltage level for recharging without detriment to battery life.
The Charging System Description and Operation is divided into 3 sections. The first section describes the charging system components and their integration into the EPM. The second section describes charging system operation. The third section describes the instrument panel cluster (IPC) operation of the charge indicator, driver information center (DIC) messages, and voltmeter operation.
Charging System Operation
The purpose of the charging system is to maintain the battery charge and vehicle loads. There are 2 modes of operation and they include
- Charge Mode
- Voltage Reduction Mode
The engine control module (ECM) controls the generator through the generator field control circuit. It monitors the generator performance though the generator field duty cycle signal circuit. The ECM controls the generator through the generator field control circuit. The signal is a 10-volt pulse width modulation (PWM) signal of 128 Hz with a duty cycle of 0-100 percent. Normal duty cycle is between 5-95 percent. Between 0-5 percent and 95-100 percent are for diagnostic purposes. The following table shows the commanded duty cycle and output voltage of the generator
| Commanded Duty Cycle | Generator Output Voltage |
|---|---|
| 10% | 11 V |
| 20% | 11.56 V |
| 30% | 12.12 V |
| 40% | 12.68 V |
| 50% | 13.25 V |
| 60% | 13.81 V |
| 70% | 14.37 V |
| 80% | 14.94 V |
| 90% | 15.5 V |
Charging System Description and Operation
The generator provides a feedback signal of the generator voltage output through the generator field duty cycle signal circuit to the ECM. This information is sent to the instrument panel module (IPM). The signal is a 5-volt PWM signal of 128 Hz with a duty cycle of 0-100 percent. Normal duty cycle is between 5-99 percent. Between 0-5 percent and 100 percent are for diagnostic purposes.
Charge Indicator Operation
The instrument panel cluster (IPC) illuminates the charge indicator and displays a warning message in the driver information center (DIC) when the one or more of the following occurs
- The engine control module (ECM) detects that the generator output is less than 11 volts or greater than 16 volts. The IPC receives a GMLAN message from the ECM requesting illumination.
- The IPC determines that the system voltage is less than 11 volts or greater than 16 volts for more than 30 seconds. The IPC receives a GMLAN message from the instrument panel module (IPM) indicating there is a system voltage range concern.
- The IPC performs the displays test at the start of each ignition cycle. The indicator illuminates for approximately 3 seconds.
- The ignition is ON, with the engine OFF.
Starting System Description and Operation
The PG model starter motors are non-repairable. They has pole pieces that are arranged around the armature. Both solenoid windings are energized. The pull-in winding circuit is completed to the ground through the starter motor. The windings work together magnetically to pull and hold in the plunger. The plunger moves the shift lever. This action causes the starter drive assembly to rotate on the armature shaft spline as it engages with the flywheel ring gear on the engine. Moving at the same time, the plunger also closes the solenoid switch contacts in the starter solenoid. Full battery voltage is applied directly to the starter motor and it cranks the engine.
As soon as the solenoid switch contacts close, current stops flowing thorough the pull-in winding because battery voltage is applied to both ends of the windings. The hold-in winding remains energized; its magnetic field is strong enough to hold the plunger, shift lever, starter drive assembly, and solenoid switch contacts in place to continue cranking the engine. When the engine starts, pinion overrun protects the armature from excessive speed until the switch is opened.
When the engine control module (ECM) sees an engine run flag, the ground is removed from the control circuit of the Starter relay. The switch side of the Starter relay opens and battery voltage is removed from the starter solenoid S terminal. Current flows from the motor contacts through both windings to the ground at the end of the hold-in winding. However, the direction of the current flow through the pull-in winding is now opposite the direction of the current flow when the winding was first energized.
The magnetic fields of the pull-in and hold-in windings now oppose one another. This action of the windings, along with the help of the return spring, causes the starter drive assembly to disengage and the solenoid switch contacts to open simultaneously. As soon as the contacts open, the starter circuit is turned OFF.