P0BC1
DTC P0BC1
Diagnostic Instructions
* Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure. Initial Inspection and Diagnostic Overview
* Review Strategy Based Diagnosis for an overview of the diagnostic approach.
* Diagnostic Procedure Instructions provides an overview of each diagnostic category.
DTC Descriptor
DTC P0BC1
- Drive Motor Battery Fan Relay Failure
Diagnostic Fault Information
Typical Scan Tool Data
Circuit/System Description
The drive motor generator battery vent fan relay is a normally open relay. The relay armature is held in the open position by spring tension. Battery positive voltage is supplied directly to the relay coil and the armature contact at all times. The battery energy control module (BECM) grounds the control circuit through a low side output driver. When the BECM commands the vent fan relay ON, the relay contacts close and ignition voltage is supplied directly to the drive motor generator battery vent fan motor. A 5-volt circuit is provided from the vent fan motor assembly, to the BECM. The BECM uses a pulsed width modulated (PWM) signal on the 5 volt circuit to control the vent fan motor duty cycle
Conditions for Running the DTC
* The vehicle power mode is RUN.
* Accessory voltage is 9-18 volts.
Conditions for Setting the DTC
* Fan speed commanded on at 35 percent or higher.
* Fan control signal monitor voltage to BECM greater than 0.9 volts.
Action Taken When the DTC Sets
DTC P0BC1 is a Type B DTC.
Conditions for Clearing the DTC
DTC P0BC1 is a Type B DTC.
Diagnostic Aids
Check for a battery vent fan relay stuck closed.
Special Tools
EL-48900 HEV Safety Kit
Circuit/System Verification
1. Ignition ON, engine OFF, with scan tool, command the battery vent fan motor to 80 percent duty cycle. The battery vent fan should turn ON and run at high speed.
2. Operate the vehicle within the Conditions for Running the DTCs. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records data.
Circuit/System Testing
Danger: Always perform the High Voltage Disabling procedure prior to servicing any High Voltage component or connection. Personal Protection Equipment (PPE) and proper procedures must be followed.
The High Voltage Disabling procedure will perform the following tasks:
* Identify how to disable high voltage
* Identify how to test for the presence of high voltage
* Identify condition under which high voltage is always present and personal protection equipment (PPE) and proper procedures must be followed.
* Failure to follow the procedures exactly as written may result in serious injury or death.
Ignition OFF, disable the high voltage at the drive motor generator battery. Refer to High Voltage Disabling.
1. Remove the drive motor generator battery case upper cover, front cover, and right side cover.
2. Ignition OFF, connect the 12 volt battery.
3. Disconnect the X14 at the vent fan relay.
4. Ignition OFF, connect a test lamp at X14 between terminals 1 and 2. The test lamp should not illuminate.
^ If the test lamp illuminates, test the vent fan relay control circuit for a short to ground. If the circuit tests normal, replace the BECM.
5. Ignition ON, connect a test lamp at X14 terminal 4 and ground. The test lamp should not illuminate.
^ If the test lamp illuminates, test the B+ circuit to the vent motor for a short to voltage.
6. Ignition OFF, disconnect X13 at the drive motor generator battery vent fan.
7. Ignition ON, connect a test lamp at X13 terminal 4. The test lamp should not illuminate. If the test lamp illuminates, test the 5 volt reference circuit for a short to voltage. If the circuit tests normal, replace the BECM.
8. If all circuits test normal, replace the drive motor generator battery vent fan relay.
Component Testing
Danger: Always perform the High Voltage Disabling procedure prior to servicing any High Voltage component or connection. Personal Protection Equipment (PPE) and proper procedures must be followed.
The High Voltage Disabling procedure will perform the following tasks:
* Identify how to disable high voltage
* Identify how to test for the presence of high voltage
* Identify condition under which high voltage is always present and personal protection equipment (PPE) and proper procedures must be followed.
* Failure to follow the procedures exactly as written may result in serious injury or death.
Ignition OFF, disable the high voltage at the drive motor generator battery. Refer to High Voltage Disabling.
1. Ignition OFF, disconnect the drive motor generator battery vent fan relay.
2. Test for 85-110 ohms across terminal 1 and terminal 2 on the relay.
^ If the resistance is not within the specified range, replace the drive motor generator battery vent fan relay.
3. Test for infinite resistance between terminals 3 and 4 on the relay. If continuity is detected, replace the drive motor generator battery vent fan relay.
Repair Instructions
Perform the Diagnostic Repair Verification after completing the repair. Verification Tests
* Generator Battery Vent Fan Relay Replacement
* Drive Motor Generator Battery Control Module and Bracket Replacement