Test Description
The number below refers to the step number on the diagnostic table.
- 3: This step compares battery voltage with the voltage that the BCM calculates.
| Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
| Connector End View Reference: Inline Harness Connector End Views in Wiring Systems or Computer/Integrating Systems Connector End Views in Computer/Integrating 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. With a scan tool, observe the Battery Voltage Signal parameter in the Engine Electrical BCM data list. Does the scan tool indicate the Battery Voltage Signal parameter is greater than the specified value? | 8.8 V | Go to Step 5 | Go to Step 3 |
| 3 | Measure the voltage across the battery terminals. Compare the battery voltage with the Battery Voltage Signal parameter. Are the voltages within the specified value? | 1 V | Go to Battery Inspection/Test | Go to Step 4 |
| 4 | Test the battery positive voltage and ground circuits of the body control module (BCM) for a high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems. Did you find and correct the condition? | Go to Step 7 | Go to Step 5 | |
| 5 | Inspect for poor connections at the harness connector of the BCM. 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 7 | Go to Step 6 | |
| 6 | IMPORTANT: Perform the setup procedure for the BCM. Replace the BCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup and programming.Did you complete the replacement? | Go to Step 7 | ||
| 7 | Use the scan tool in order to clear the DTC. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text. Does the DTC reset? | Go to Step 2 | System OK | |
| IMPORTANT |
|---|
| Perform the setup procedure for the BCM. |
DTC B1327
The number below refers to the step number on the diagnostic table.
- 3: This step compares battery voltage with the voltage that the BCM calculates.
| Step | Action | Value(s) | 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 | Install a scan tool. Start the engine. Increase engine speed to above 1,500 RPM. With a scan tool, observe the Battery 1 parameter in the BCM data list. Does the scan tool indicate the battery voltage is less than the specified value? | 17 V | Go to Step 4 | Go to Step 3 |
| 3 | Measure the voltage across the battery terminals. Compare the battery voltage with the Battery 1 parameter in the Ignition data list of the BCM. Are the voltages within the specified value? | 1 V | Go to Charging System Test | Go to Step 4 |
| 4 | Inspect for poor connections at the harness connector of the body control module (BCM). 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 6 | Go to Step 5 | |
| 5 | IMPORTANT: Perform the setup procedure for the BCM. Replace the BCM. Refer to Control Module References in Computer/Integrating Systems for replacement, setup and programming.Did you complete the replacement? | Go to Step 6 | ||
| 6 | Use the scan tool in order to clear the DTC. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text. Does the DTC reset? | Go to Step 2 | System OK |
| IMPORTANT |
|---|
| Perform the setup procedure for the BCM. |
DTC B1328
The numbers below refer to the step numbers on the diagnostic table.
- 2: Listen for an audible click when the crank 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 crank relay.
- 4: This step verifies that the ECM is providing ground to the crank relay.
- 5: This step tests if ground is constantly being applied to the crank relay.
| Step | Action | Yes | No |
|---|---|---|---|
| Schematic Reference: Engine Controls Schematics for the 3.9L (LZ9) engine or Starting and Charging Schematics Connector End View Reference: Power and Grounding Connector End Views or Engine Control Module (ECM) Connector End Views | |||
| 1 | Did you perform the Diagnostic System Check - Vehicle? | Go to Step 2 | Go to Diagnostic System Check - Vehicle |
| 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 crank relay click with each command? | Go to Step 3 | Go to Starter Solenoid Does Not Click |
| 3 | Turn OFF the ignition. Remove the crank relay. Turn ON the ignition, with the engine OFF. Probe the crank relay coil supply voltage circuit of the crank 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 crank relay control circuit and the crank 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 crank relay for a short to voltage or an open. Refer to Circuit Testing and Wiring Repairs . Did you find and correct the condition? | Go to Step 11 | Go to Step 7 |
| 6 | Inspect for poor connections at the crank relay. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs . 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 . Did you find and correct the condition? | Go to Step 11 | Go to Step 10 |
| 8 | Repair the battery positive voltage circuit of the crank relay. Refer to Connector Repairs . Did you complete the repair? | Go to Step 11 | |
| 9 | Replace the crank relay. Did you complete the replacement? | Go to Step 11 | |
| 10 | Replace the ECM. Refer to Control Module References 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
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, manage the load, improve battery state-of-charge (SOC) 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 adjusting the regulated voltage.
- It performs diagnostics and driver notification.
The battery's condition is estimated during key-off and during key-on. During key-off the 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 key-on, the algorithm continuously estimates SOC based on adjusted net amp hours, battery capacity, initial SOC and temperature.
While running, the battery's 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's 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 parts. The first part describes the charging system components and their integration into the EPM. The second part describes charging system operation. The third part 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 6 modes of operation and they include
- Charge Mode
- Fuel Economy Mode
- Voltage Reduction Mode
- Start Up Mode
- Windshield Deice Mode
- Battery Sulfation Mode
The powertrain control module (PCM)/engine control module (ECM) controls the generator through the generator field control circuit. It monitors the generator performance through the generator field duty cycle signal circuit. The signal is a pulse width modulated (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 PCM/ECM, this information is sent to the body control module (BCM). The signal is a 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 in the message center when the one or more of the following occurs
- The powertrain control module (PCM)/engine control module (ECM) detects that the generator output is less than 11 volts or greater than 16 volts. The IPC receives a class 2 message from the PCM/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 class 2 message from the body control module (BCM) 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 starter motors on this vehicle are non-repairable starter motors. They have 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 ignition switch is released from the START position, the crank 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.