Rx400H 2008 - CHECK HYBRID SYSTEM - CHECK VSC SYSTEM -

david-now · December 5, 2023

Ive had my 2008 RX400H for almost 3 years and it has been faultless , taken from 88,000 to 110,000 miles

Last Friday morning with heavy overnight snow I started the car and put on heaters and left the car for 15 mins to warm through. When I returned the engine was off but heaters on. I turnd the ignition off but when I tried to start the car a short while later it would not go. I tried it again 30 minutes later and it was fine. Ive used the car for last few days including 2 journeys of over 100 miles without problem.

Today, I was driving along when the message 'CHECK HYBRID SYSTEM' appeared on dash. I continued to my destination ok, but when I tried to start the car I got the same message and it wouldn't drive.

A quick google and I disconnected 12v Battery for 10 minutes then reconnected and the car started / drove. However the 2 messages CHECK HYBRID SYSTEM - CHECK VSC SYSTEM appeared on dash , I drove home, parked on my drive and the car again will not start.

Does this sound like a 12V Battery problem ? Sounds unlikely that hybrid and VSC would fail on same day.

The 12V Battery looks old and was on the car when I bought it March 2020 and could be much older.

If I did replace the 12V Battery would the system also need reset ?

Any suggestions welcome.

Thanks

NemesisUK · December 5, 2023

12 minutes ago, david-now said:

I started the car and put on heaters and left the car for 15 mins to warm through. When I returned the engine was off but heaters on. I turnd the ignition off

Why did you "turn the ignition off"?

david-now · December 5, 2023

I'm not recommending turning ignition off , simply reporting what i did.

Spock66 · December 5, 2023

I think changing the 12V Battery is a good place to start, certainly looks old, there is probably a date code on it somewhere.

Bluemarlin · December 5, 2023

Looks to me like a 12v Battery issue too.

Russell Wheeler · December 5, 2023

Check for water leaks, if water gets in to the hybrid system it causes all sorts of problems. There are lots of posts about leaks and how to cure

NemesisUK · December 5, 2023

58 minutes ago, david-now said:

I'm not recommending turning ignition off , simply reporting what i did.

Understood but why did you turn it off?

david-now · December 5, 2023

thanks for the helpful replies , much appreciated

b4u2 · December 5, 2023

@david-now

let us know what happens in the end

Greisingel · December 7, 2023

Get TIS on it.

Could be wet Hybrid Battery. Has been pretty wet recently. Thing about Hybrid engine is that is often off when running heating. So long as it is in park you're ok.

Yes, make sure the aux Battery is well charged.

david-now · December 8, 2023

Thanks for all the feedback.

I changed the 12v Battery and everything has been OK for the last couple of days.

The old Battery had a 2017 label on it.

Greisingel · December 8, 2023

2 hours ago, david-now said:

Thanks for all the feedback.

I changed the 12v battery and everything has been OK for the last couple of days.

The old battery had a 2017 label on it.

2017? You did pretty OK with 6 years. 👍

Keeling54 · December 8, 2023

I had the same with mine, it's been off the road since its failed MOT in October, tried to start it the other day and it was completely dead, fitted a new Battery and the dash lit up like a Christmas tree, AWD warning, Hybrid Battery waning, all sorts, turned it off and just turned the ignition on without starting it, the warning lights then cleared one by one. It was fine after that.

It's being welded tomorrow so we'll see if it does it again when they've finished patching it up.

Robinhalifax · January 3

On 12/5/2023 at 3:24 PM, david-now said:

Ive had my 2008 RX400H for almost 3 years and it has been faultless , taken from 88,000 to 110,000 miles

Last Friday morning with heavy overnight snow I started the car and put on heaters and left the car for 15 mins to warm through. When I returned the engine was off but heaters on. I turnd the ignition off but when I tried to start the car a short while later it would not go. I tried it again 30 minutes later and it was fine. Ive used the car for last few days including 2 journeys of over 100 miles without problem.

Today, I was driving along when the message 'CHECK HYBRID SYSTEM' appeared on dash. I continued to my destination ok, but when I tried to start the car I got the same message and it wouldn't drive.

A quick google and I disconnected 12v battery for 10 minutes then reconnected and the car started / drove. However the 2 messages CHECK HYBRID SYSTEM - CHECK VSC SYSTEM appeared on dash , I drove home, parked on my drive and the car again will not start.

Does this sound like a 12V battery problem ? Sounds unlikely that hybrid and VSC would fail on same day.

The 12V battery looks old and was on the car when I bought it March 2020 and could be much older.

If I did replace the 12V battery would the system also need reset ?

Any suggestions welcome.

Thanks

I have exactly the same issue as this, had the guy out from the RAC who read the codes for me, the main code seemed to be P0AA6, "Hybrid/EV Battery Voltage System Isolation Fault", there were a number of voltage mismatch errors etc but I don't recall the codes, i'll get it done again. In my case, I parked at my local suremarket and all was well, when I came back out, check hybrid system and che vsc system warnings, dash lights on as normal but no engine start and when I tried to turn the ignition key the final step as if to startm I got the message put vehicle in park to stsrt. I took the terminals off the aux Battery (which is brand new a couple of weeks ago), left it 5 mins, all started and ran ok, parked it at home, turned the ignition off and back on, same message, same results. Not sure exactly what real world error the crypytic message "Hybrid/EV Battery Voltage System Isolation Fault" means but I'll be checking a few things, 1 - the three vents under the rear seat for clogging with crap, 2 - the expansion tank to make sure that there is enough coolant to actually circulate around the inverter etc, 3 - in and around Hybrid Batter area under the rear seats for water / leaks, 5 - the three cooling fans in the Hybrid Battery casing to make sure they are working correctly. If none of that cures the issue, looks like some expensive dignosis tests and a qualified garage (but not a dealer). I think it may even be possible to have a few dead cells, not sure how many would need to be dead to reduve the actuating voltage required for the vehicle to initially start but i'm guessing that even 2 or 3 would have the effect. Anyone any other experiance of this issue and have different codes and maybe a happy fixed outcome? Cheers

Robinhalifax · January 4

Update, checked the Hybrid Coolant level, it seemed a little low, closer inspection told me it was, topped it up, worked a treat, no errors now!

ColinBarber · January 4

38 minutes ago, Robinhalifax said:

Update, checked the Hybrid Coolant level, it seemed a little low, closer inspection told me it was, topped it up, worked a treat, no errors now!

Keep an eye on the level, it shouldn't drop as there is nowhere for the coolant to go in a fully working sealed system.