Jeza

That's the same configuration as mine with the aux battery under the drivers seat and leisure one in the console. There is a slight drain on the aux battery due to immobiliser, alarm, radio, various ecu's bit should not drain the battery in a few days. Try disconnecting the leisure battery to check the split charge relay is working correctly and not allowing the leisure side to take power from the aux battery. My aux battery is only a 45Ah AGM as it is squeezed under the seat.

When you say you have anAlphard conversion, is that a camper? If so do you have a leisure battery with split charge relay? Is the 12v auxiliary battery still in the centre console or moved somewhere else, just making sure you are looking at the correct battery.

What age is it and does it have the theatre sound system? I have 10 series wiring diagrams

There is no conventional starter motor on a hybrid. Initial start uses the Hybrid motor within the gearbox, subsequent starts, while driving, uses the starter/generator mounted on the back of the engine driven/driving the serpentine belt.

Basically no. There is an HV battery charger costing ££££ connecting it involves disconnecting the HV battery cables at the inverter to attach to the charger. A lead also goes to the HV battery ecu. With the HV leads disconnected from the inverter there is no way to get a/c power to the air-conditioning pump. Portable aircon unit required!

Check the engine earth strap as well

Don't use Gen 1 cells. 10 series Alphards came with Gen2 cells, I have had the pack replaced with Gen 4 Prius cells.

Air con system wiring diagram, 10 series hybrid. The Air conditioner amplifier (2 way) is located to the left of the radio head unit. The Air Conditioner Amplifier is within the heat/vent/distribution control panel below the head unit. Air con system wiring ATH10.pdf

After individual cell replacement in 2023 a year later another cell went bad so I decided to bite the bullet and replace the whole pack. 2003 with 130,000km is not a bad life for the battery. I went with Gen 4 cells which are the latest and I certainly notice a difference, slightly better acceleration and longer battery only around town. hanks to Hybrid Battery Repair, Glasgow.

Yes I do, I will have a look and get it posted up but the A/C system is complicated as it is tied into several systems.

Wiring diagrams of the HV system with most of the Japanese translated manually, and using GIMP to add the text. I could not find any other way to do it with this type of pdf with embedded text within images and retain the quality. Hope it is of some use to you all. Alphard HV wiring 10 series pt1.pdf Alphard HV wiring 10 series pt2.pdf

On the Hybrid there is no starter relay as such, the engine is initially started using the Hybrid motor in the gearbox. Subsequent stop/starts uses the starter generator via the serpentine belt. Check the gear lever is in park and "P" is displayed on the dash.

The Hybrid battery system never fully charges the battery during general driving so there is spare capacity for regeneration braking. This also keeps the battery temp down as the inner cells of the pack are prone to overheat and fail as I have found out.

Yes there are, but it will not change the road tax, likewise very little info will get transferred from the Japanese Type Certificate to the logbook. The log book info all comes from the Europe Type approval regs and as the Japan one is not in the correct format DVLA can not transfer the info. Mine is just a Toyota, I did get the fuel changed to Gas Bi-Fuel and added exhaust emissions. pictures from V5 and CofC

I presume it is the ABS unit which has an electric pump and accumulator in it. I have had an unexpected leak from the accumulator, after it had been in the garage for an MOT, which lights up several warnings. I suspect they had pushed the brake pads back away from the disc, anyway a few hard pumps of the brake pedal cleared the fault. A bit of muck on a check valve?