My 2006 HiHy 4WD-i with 26K miles had its traction battery fail this past Saturday.

The symptoms were that the ICE continued to run at all times, the regen braking no longer worked, the battery SOC indicator was moving up and down at a faster than normal pace, and the following warning lights were on:

- master warning
- check engine
- traction control (the skidding car)
- brake (the circle with exclamation point)

Also, the alpha display said to "check VSC system" and "check hybrid system".

On Saturday, my local dealer's mechanic retrieved the following DTC:

P0A80: Replace Hybrid Battery Pack (this is issued when the voltage difference between pairs of battery modules exceeds the standard)
C1259: HV System Regenerative Malfunction
C1310: Malfunction in HV System

He diagnosed that the traction battery had failed. Toyota tech support confirmed this diagnosis, and the new battery has arrived at the dealership. Hopefully the new battery will be installed tomorrow.

In the meantime, I have been driving a 2007 Camry LE 4-cyl loaner. Smooth and quiet ride, but by no means overpowered.

I haven't noticed other posts regarding HiHy traction battery replacement, so I thought group members might be interested to know what symptoms might point to a failed traction battery.

Patrick Wong

What type of driving did you do with it? City, Highway, Mix?

Just curious because I was driving our 07 4wd-i in heavy rains today and the traction control worked just great at 60 miles per hour. I was astonished how well it drove under difficult conditions.

When will the 2008 Highlander Hybrids come out and how much can they tow? The answer is 07/28/08 and 3500 lbs with 350 lbs tongue weight.

08/15/07 Update. The hitch will be a class 3 valley hitch.

As of 08/19/07 3 weeks to the 08's. Maybe soon we can order them.

As of 9/9/07 Broke down and bought a "gas" Sport Highlander. The Hybrids are delayed till October-November and could not wait.

Hi Peter,

Our HiHy receives a mix of city/highway driving and delivers mid-20s mpg using Shell 91 octane. The SUV has been lightly driven recently as most of our miles are logged on the two Prius.

I agree that the HiHy traction control is great on snowy and rainy roads; no complaints. I installed Bridgestone Dueler H/L Alenza tires after 6K miles as I did not like the Goodyear Integrity tires, which were ~40% worn at that point. The Bridgestone tires are on track to deliver about 50K miles of wear.

Patrick Wong

When you get it back, can you ask what they think caused the failure? Just curious as another hhy 4wd-i owner.

When will the 2008 Highlander Hybrids come out and how much can they tow? The answer is 07/28/08 and 3500 lbs with 350 lbs tongue weight.

08/15/07 Update. The hitch will be a class 3 valley hitch.

As of 08/19/07 3 weeks to the 08's. Maybe soon we can order them.

As of 9/9/07 Broke down and bought a "gas" Sport Highlander. The Hybrids are delayed till October-November and could not wait.

Just to clarify, the traction battery is not related to the traction control.

I got the HiHy back from the dealer this afternoon. The mechanic told me that one cell had failed (out of 240). No particular explanation about why the cell failed. The part number of the traction battery is G9510-48010 and MSRP is $5,339.

The mechanic had to remove the third row and second row seating to gain access to the battery. The battery is located under the second row seat. It is organized into three groups. There are two groups of 12 modules each, on the two ends. There also is a center group of 6 modules. Each module has eight cells, hence nominal voltage is 9.6V per module or 288V for the battery. The battery housing also has space to mount three battery fans, the system main relays, and the battery ECU. Those components must be moved from the old battery housing to the new battery housing.

Compare to the current generation Prius traction battery which has six cells per module, hence producing 7.2V per module. It contains 28 modules, so the battery generates 201.6V nominal. The battery is a single long rectangular block, like a loaf of sliced bread.

Patrick Wong

Thanks for the information and the details. I was curious about the battery and I have not talked with anyone else with a 4wd-i hence my question.

Discouraging that one cell could cost you 5,339$.

When will the 2008 Highlander Hybrids come out and how much can they tow? The answer is 07/28/08 and 3500 lbs with 350 lbs tongue weight.

08/15/07 Update. The hitch will be a class 3 valley hitch.

As of 08/19/07 3 weeks to the 08's. Maybe soon we can order them.

As of 9/9/07 Broke down and bought a "gas" Sport Highlander. The Hybrids are delayed till October-November and could not wait.

Does the HiHy require 91 octane fuel? It was my understanding that the correct fuel for this vehicle is 87, and that the Lexus RX hybrid was the only version of this vehicle tuned for premium.

91 octane fuel is recommended by Toyota for the HiHy. I believe that the HiHy and RX400h powertrains are identical. Their specs are the same.

Patrick Wong

One bad cell and the whole battery pack needs to be replaced!?

They really need to make the batteries more modular, so that when a cell goes bad, a mechanic (or electrician) can replace it.

A lot of people are really scared that the battery pack will fail out of warranty in these cars. I don’t blame them.

Although I will not own my Mercury Mariner more than 100,000 miles, it would scare me out of buying it used and having a $????? Dollar battery pack fail.

Also, why no aftermarket startup company making refurbished battery packs? Seems that the Insight people are going to own their cars forever

Just my 2 cents!