Diagnostic Instructions

DTC Descriptors

DTC P0AC0: Hybrid Battery Current Sensor Performance

DTC P0AC1: Hybrid Battery Current Sensor Circuit Low Voltage

DTC P0AC2: Hybrid Battery Current Sensor Circuit High Voltage

DTC P1A07: Battery Energy Control Module 5-Volt Reference Circuit

Diagnostic Fault Information

Circuit	Short to Ground	Open/High Resistance	Short to Voltage
Current Sensor 5 Volt Reference	P1A07	P0AC1	P1A07
Current Sensor Signal	P0AC1	P0AC2	P0AC2, P1A07
Current Sensor Low Reference	--	P0AC2	--

Typical Scan Tool Data

Calc Hybrid Batt Current Sen

Circuit	Short to Ground	Open	Short to Voltage
Operating Conditions: Accessory voltage is 9-18 volts, vehicle power mode is RUN Parameter Normal Range: -249 to +249 Amps
Sensor Signal Return	+238 Amps	-249 Amps	-249 Amps
5 V Reference	+250 Amps	+235 Amps	-249 Amps

Current Sen High Range

Circuit	Short to Ground	Open	Short to Voltage
Operating Conditions: Accessory voltage is 9-18 volts, vehicle power mode is RUN Parameter Normal Range: Varies
Sensor Signal Return	+238 Amps	-249 Amps	-249 Amps
5 V Reference	+250 Amps	+235 Amps	-249 Amps

Current Sen Medium Range

Circuit	Short to Ground	Open	Short to Voltage
Operating Conditions: Accessory voltage is 9-18 volts, vehicle power mode is RUN Parameter Normal Range: Varies
Sensor Signal Return	+62 Amps	-60 Amps	-53 Amps
5 V Reference	-63 Amps	+62 Amps	-54 Amps

Current Sen Low Range

Circuit	Short to Ground	Open	Short to Voltage
Operating Conditions: Accessory voltage is 9-18 volts, vehicle power mode is RUN Parameter Normal Range: Varies
Sensor Signal Return	+25 Amps	-24 Amps	-23 Amps
5 V Reference	-25 Amps	+24 Amps	-73 Amps

Circuit/System Description

The drive motor generator battery control module is also referred to as the battery energy control module (BECM). The BECM will diagnose its own systems and determine when a fault condition is present. Diagnostics and system status is communicated from the BECM to the hybrid powertrain control module (HPCM) through the Hybrid LAN communication circuit. The HPCM is the host controller for diagnostic trouble code (DTC) information.

The hybrid battery current sensor is mounted inside the drive motor generator battery assembly. The positive high voltage cable that foes to the positive contactor relay passes through the current sensor. The current sensor detects the amperage that flows in and out of the hybrid batteries. The BECM monitors and supplies a 5-volt reference signal to the current sensor. The current sensor has a return voltage signal between 0 and 5 volts to the BECM. The current sensor return voltage signal is in proportion to the amperage going in and out of the drive motor generator battery. A return signal voltage of the current sensor above 2.5 volts indicates that the drive motor generator battery is being discharged and a return signal voltage below 2.5 volts indicates charging. The hybrid battery current sensor has 3 measurement ranges in order to maintain accuracy. The ranges are low, medium and high. The measurement ranges of the current sensor have some overlap with each other. The low range measures from -22 to +22 amps. The medium Range sensor measures from -52 to +52 amps. The high range current sensor measures from -250 to +250 amps.

Conditions for Running the DTC

Conditions for Setting the DTC

P0AC0

The BECM detects more than 5 amps on the current sensor after a successful HV system power down and after the contactors have opened, OR

The BECM detects an increase in total pack voltage of more than 10 volts and measures less than 0.5 amp increase at the current sensor, OR

The BECM detects less than 20 amps on the high range sensor and the difference between the high range current measurement and the medium range current measurement is greater than 20 amps or the difference between the high range current measurement and the low range current measurement is greater than 4 amps for 3 out of 10 seconds.

P0AC1

The BECM detects that the current sensor high range is greater than +200 amps and the current sensor medium range is greater than +52 amps and the current sensor low range is greater than +22 amps for 3 out of 4 seconds.

P0AC2

The BECM detects that the current sensor high range is less than -200 amps and the current sensor medium range is less than -52 amps and the current sensor low range is greater than -22 amps for 3 out of 4 seconds.

P1A07

The BECM detects less than 4.8 volts or greater than 5.2 volts on the 5-volt reference circuit for the current sensor.

Action Taken When the DTC Sets

Conditions for Clearing the DTC

DTCs P0AC0, P0AC1, P0AC2, and P1A07 are Type A DTCs.

Reference Information

Schematic Reference

Hybrid Energy Storage Schematics

Connector End View Reference

Component Connector End Views

Electrical Information Reference

Scan Tool Reference

Control Module References for scan tool information

Special Tools

EL-48900 HEV Safety Kit

Circuit/System Verification

1. Clear the DTC information.
2. Turn the ignition OFF for 3 minutes.
3. Turn the ignition ON.
4. Retest for DTCs P0AC0, P0AC1, P0AC2, and P1A07.
5. Operate the vehicle within the Conditions for Running the DTC. 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.
1. Ignition OFF, disable the high voltage at the drive motor generator battery. Refer to High Voltage Disabling .
2. Remove the drive motor generator battery case upper cover, front cover and right side cover. Refer to Drive Motor Battery Case Upper Cover, Front Cover, and Right Side Cover Replacement .
3. Ignition OFF, connect the 12 volt battery.
4. Disconnect the harness connector at the current sensor.
5. Ignition OFF, test for less than 2 ohms between low the reference circuit terminal 2 and ground at the harness connector.

⇒	If greater than the specified range, test the low reference circuit for a open/high resistance. If the circuit tests normal, replace the drive motor generator battery control module.

6. Ignition ON, test for 4.9-5.1 volts between the 5-volt reference terminal 1 and ground.

⇒	If not within the specified range, test the 5-volt reference circuit for a short to voltage, short to ground, or an open/high resistance. If the circuit tests normal, replace the drive motor generator battery control module.

7. Ignition ON, test for 4.7-5.3 volts between the signal circuit terminal 3 and ground.

⇒	If not within the specified range, test the signal circuit for a short to voltage, short to ground, or an open/high resistance. If the circuit tests normal, replace the drive motor generator battery control module.

8. If all circuits test normal, replace the current sensor.

Repair Instructions

Perform the Diagnostic Repair Verification after completing the repair.