P0AFA

P112 HYBRID BATTERY CONTROL: HYBRID BATTERY SYSTEM: P0AFA: Hybrid Battery System Voltage Low

DTC P0AFA - Hybrid Battery System Voltage Low

DESCRIPTION

The HV battery assembly consists of nickel hydride batteries. Nickel hydride batteries do not require external charging. The SOC (state of charge) of the HV battery is maintained at a constant voltage level by the hybrid vehicle control ECU while the vehicle is being driven. In the HV battery assembly, 28 modules are connected in series, and each module has six 1.2 V cells that are connected in series. Thus, the HV battery assembly contains a total of 168 cells which produce 201.6 V.
The battery ECU, which monitors two modules as a single battery block, detects the battery block voltage at a total of 14 locations.

MONITOR DESCRIPTION

The battery ECU monitors a voltage of the battery blocks to detect an open malfunction in internal battery voltage sensor circuits of the battery ECU and the wire harness between each battery block and battery ECU. If a voltage at one of the battery blocks is below a standard level or of all the battery blocks is within a specified range, the battery ECU judges that there is an open in the internal sensor circuit(s) or wire harness. The battery ECU then illuminates the MIL and sets a DTC.

MONITOR STRATEGY

TYPICAL ENABLING CONDITIONS

TYPICAL MALFUNCTION THRESHOLDS

COMPONENT OPERATING RANGE

WIRING DIAGRAM

INSPECTION PROCEDURE
CAUTION:
- Before inspecting the high-voltage system, take safety precautions to prevent electrical shocks, such as wearing insulated gloves and removing the service plug grip. After removing the service plug grip, put it in your pocket to prevent other technicians from reconnecting it while you are servicing the high-voltage system.
- After disconnecting the service plug grip, wait for at least 5 minutes before touching any of the high-voltage connectors or terminals.
HINT: At least 5 minutes are required to discharge the high-voltage condenser inside the inverter.

PROCEDURE

1. READ DTC OUTPUT (DTC P0A1F IS OUTPUT)
(a) Connect the Techstream to the DLC3.
(b) Turn the power switch ON (IG) and the tester ON.
(c) Enter the following menus: Powertrain / HV Battery / DTC.
(d) Read DTCs.
Result:
DTC P0A1F is output
YES -- REPLACE BATTERY ECU
NO -- Continue to next step.

2. READ VALUE USING TECHSTREAM (BATTERY BLOCK VOL-V01 TO V14)
(a) Connect the Techstream to the DLC3.
(b) Turn the power switch ON (IG) and the tester ON.
(c) Enter the following menus: Powertrain / HV Battery / Data List.
(d) Read "V1 to V14 Batt Block" on the tester.
Standard voltage:
2 V or more
OK -- CHECK CONNECTION OF NO. 2 FRAME WIRE CONNECTOR
NG -- Continue to next step.

3. CHECK JUNCTION BLOCK ASSEMBLY (BUSBAR MODULE)
CAUTION: Wear insulated gloves and goggles before performing the following operation.

(a) Remove the battery assembly Removal.
(b) Remove the battery cover Removal.
(c) Check that the nuts of the junction block are tightened to the specified torque.
Torque: 5.4 Nm (55 kgf-cm, 48 in-lbf)
NG -- TIGHTEN NUTS TO SPECIFIED TORQUE
OK -- Continue to next step.

4. CHECK NO. 2 FRAME WIRE (BUSBAR MODULE)
CAUTION: Wear insulated gloves and goggles before performing the following operation.

(a) Check that the nuts of the No. 2 frame wire are tightened to the specified torque.
Torque: 5.4 Nm (55 kgf-cm, 48 in-lbf)
NG -- TIGHTEN NUTS TO SPECIFIED TORQUE
OK -- Continue to next step.

5. CHECK CONNECTION OF NO. 2 FRAME WIRE CONNECTOR
CAUTION: Wear insulated gloves before performing the following operation.

(a) Check the connection condition of the B12 battery ECU connector.
OK:
Connector has been connected securely and there is no poor connection.
NG -- CONNECT SECURELY
OK -- Continue to next step.

6. INSPECT NO. 2 FRAME WIRE (BUSBAR MODULE)
CAUTION: Wear insulated gloves and goggles before performing the following operation.

(a) Remove the No. 2 frame wire Removal.
(b) Measure the resistance of each connector and the metal portions of the No. 2 frame wire.
Standard resistance: