mag08

I did not drive my 2008 LS600HL for a while and the battery died. After charging the battery back (battery changed in Nov. 2019), I was able to power on the car again.
But there is a "Check Hybrid System" warning displayed.

Is there a way to run a diagnostic test on the Hybrid system? Or any other suggestions to narrow down the issue?

Appreciate any help.

miket000

Using techstream I regularly clear the check hybrid message on my friends aging gs450h. His battery is going bad but the warning will stay off for months.

If you're currently able to drive it around clearing your hybrid fault may be all that is needed. If the message comes back you likely have a faulty hybrid battery. The hybrid battery is susceptible to damage from sitting unused just as your 12v battery was.

To answer your question techstream can be used to diagnose the hybrid system.

Vansibel

NiMH battery will discharge over time and Lexus actually left a note in the car owner manual stating that an unused car should be started and left idling every few months to keep the traction battery from discharging to a point where the car won't start anymore. If it was me I would clear the codes and drive the car for a good long drive and before storing the car again I would make sure the battery indicator is pretty high.

Striker223

Clear it and go drive it on the interstate for a few hours to get some charge back into the traction pack. I had a few customers with Toyota hybrids who didn't drive them during Covid and had this issue. The packs do not like sitting

mag08

Thanks.
First question, do you have instructions of how to clear the warning?

Second, I went to Auto Zone and got two diagnostic trouble codes:
1) C1256 Accumulator low pressure malfunction
2) Malfunction of HV system

My car has no issues before the battery went out. With C1256, is it still safe to drive around?

BlazeViper

Assuming it's the usual dying accumulator, eventually you will loose all brake boost at some point in the future. This makes stopping the 2 ton mammoth very difficult, or so I've read on here.
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Striker223

Extremely, 30-0 requires you to stand on it lol!

miket000

The accumulator low pressure code c1256 was likely a byproduct of the failed 12v battery / weak hybrid battery. I'd clear the codes with techstream or have a shop clear them and drive it.