P0A08 Possible Causes
- Cable harness or connector
- Water pump assembly
- Cooling system
- Hybrid vehicle transaxle assembly
- Generator cable
- Motor cable
- Frame wire
- Inverter with converter
- Fuse junction block assembly (MAIN)
- Fuse (DC/DC-S, IGCT, IGCT No. 2)
- Fuse junction block assembly (DC/DC)
What Does It Mean?
First Diagnose Code P0A08
Check the “Possible Causes” listed above. Visually inspect the cable harness and associated connectors. Check for damaged components and look for broken, bent, pushed out, or corroded connector pins.
P0A08 Possible Symptoms
Engine light on (or service engine soon warning light)
P0A08 Toyota Description
The hybrid vehicle converter (DC/DC converter) converts the 201.6 V DC from the HV battery into 12 V DC to power areas such as vehicle lighting, audio, and ECU systems. Additionally, it charges the auxiliary battery. A transistor bridge circuit initially converts 201.6 V DC into alternating current, and a transformer steps down its voltage. Then, it is rectified and smoothed (into DC) and converted into 12 V DC. The hybrid vehicle converter controls the output voltage to maintain a constant voltage across the auxiliary battery.
The Power Management Control ECU (HV CPU) uses the NODD signal line to send a shutdown command to the hybrid vehicle converter and receive signals indicating the normal or abnormal status of the 12 V charging system. If the vehicle is driven with an inoperative hybrid vehicle converter, the auxiliary battery voltage will drop, preventing continuous vehicle operation. Therefore, the Power Management Control ECU (HV CPU) monitors the operation of the hybrid vehicle converter and alerts the driver if it detects a malfunction.