Lexus 450H 12V Battery Problems

[the_biggster]

Hello all. I bought my 2007, 66k miles GS450h last weekend. Am really pleased with her, a great machine. However, I went to start her on Thursday evening and the hybrid system would not start. Instead, the dash said "check vgrs" and the ready light did not come on.

I thought that this could be an indication that the 12v Battery was low and so I boosted it with a Battery booster pack I had, and sure enough it started up fine. I took it to a motor parts shop yesterday morning who tested the Battery and it was only putting out 10v and was emitting a fizzing sound under the load test, which apparently means it has a fizzing cell and needs replacing.

So I got a new Battery from the shop, which they fitted. However, during fitting, we discovered that the old (OEM) Battery had an additional connection to a small, two pin plug (thin cable) which the new Battery did not have (I have never seen this connection before). We left it disconnected.

Upon starting the car after the Battery was fitted, all systems start up fine, and the hybrid system says "ready". However, the display says "check hybrid system" and the master warning light is lit. No amount of turning on/off the system, opening closing doors, disconnecting and reconnecting the Battery stops the check hybrid message just after I start the car. The car seems to drive just fine, but the display does not show the hybrid system energy flow and the warning light does not go out.

I figure I'll have to take it into Lexus, but does anyone have any advice on:

1. What is the extra connection on the 12v Battery for?

2. Anything else I can try to trace the fault/extinguish the warning light?

Many thanks in advance, Simon

[Parthiban]

Sorry to hear of your troubles and unfortunately I can't really help, but from everything I've heard about the hybrid system it's mighty complicated so personally I would have checked what the fault was with Lexus first before starting to replace things.........

Hope it's a simple fix though :)

[the_biggster]

I've solved the problem! The extra 2 pin connection on the 12v Battery is (I'm pretty sure) a temperature sensor (thermistor) that I removed from the old Battery, stuck to the new Battery and then ed it up! After disconnecting the negative for a couple of mins then reconnecting it - voila! No more "Check Hybrid System"!

I guess it would be safe to say that the "Check Hybrid System" warning can come on for the smallest of reasons!

I hope this post helps others who need to change their 12v Battery but don't want to pay Lexus £135 for a new one (not fitted!).

Cheers

[Parthiban]

Nice one, glad it was so simple to sort out :)

[kwezzie1]

I've solved the problem! The extra 2 pin connection on the 12v battery is (I'm pretty sure) a temperature sensor (thermistor) that I removed from the old battery, stuck to the new battery and then ed it up! After disconnecting the negative for a couple of mins then reconnecting it - voila! No more "Check Hybrid System"!

I guess it would be safe to say that the "Check Hybrid System" warning can come on for the smallest of reasons!

I hope this post helps others who need to change their 12v battery but don't want to pay Lexus £135 for a new one (not fitted!).

Cheers

Hi,

Thanks so much for your post. i am going through a similar issue and i think i could do with your help. What does "stuck to the new Battery and then ed it up" mean? Where exactly did you get your Battery purchased? what brand and spec did you get? would you be able to email me a step by step guide to fitting it especially with the sensor? if yes, please let me know.

kind regards,

[the_biggster]

Holy thread resurrection! I was contacted through eBay and asked about this. I found this thread (which I had totally forgotten about) and saw there was an unanswered question.

I taped the sensor to the new 12v Battery with electrical tape. This worked fine :)

Good luck all