Lexus GS450h check hybrid system

[Ragzv6]

Hi guys, I'm hoping someone can shed some light on my situation with this check hybrid system light on my dash. So just last week I got that dreaded message to check hybrid system with the exclamation in a yellow triangle ⚠️. So after some searching I found that disconnecting the 12v Battery and the hybrid Battery service grip plug for 15 mins solves it. It did clear the warning on the dash but after 2 days it returned again. I have run some test on techstream, which shows all 20 blocks are roughly 15v and 12v Battery is also OK.

Any suggestion would be much appreciated.

 

[Ragzv6]

[Zotto]

You should read the DTC before erasing it by techstream.

[Herbie]

The "Check Hybrid System" doesn't mean specifically the hybrid Battery.

You need to look for the DTCs (Diagnostic Trouble Codes) and tell us what they are.

[Ragzv6]

4 minutes ago, Zotto said:

You should read the DTC before erasing it by techstream.

It's showing P0A0D high voltage system inter-lock circuit high and B15F9 & B15AD codes for the navigation system. 

[peniole]

Isn't 11.7V too low for the 12V Battery?

[Ragzv6]

[Ragzv6]

9 minutes ago, Herbie said:

The "Check Hybrid System" doesn't mean specifically the hybrid battery.

You need to look for the DTCs (Diagnostic Trouble Codes) and tell us what they are.

I think it could possibly be the 12v Battery

[peniole]

In case it isn't the 12V Battery, although I would check it first, see here: http://zatonevkredit(blocked word)/repair_manuals/raw_content/AWHkRFkJU9h2CeTmBxlt

[Ragzv6]

8 minutes ago, peniole said:

Isn't 11.7V too low for the 12V battery?

I thought as it's not far off 12 then it's OK. I have just done a Google search and turns out if the voltage is between 11.7 and 11.8 then the Battery is dead. I think your right mate, I will get another 12v Battery and see what happens, fingers 🤞🏼 

[Ragzv6]

38 minutes ago, peniole said:

In case it isn't the 12V battery, although I would check it first, see here: http://zatonevkredit(blocked word)/repair_manuals/raw_content/AWHkRFkJU9h2CeTmBxlt

Thanks buddy I will bare that in mind, hopefully won't have to resort to that. Will get a new Battery tomorrow and see what happens.

[Herbie]

6 minutes ago, Ragzv6 said:

Thanks buddy I will bare that in mind, hopefully won't have to resort to that. Will get a new battery tomorrow and see what happens.

Before spending money on a new Battery, just try a set of jump leads and give it a different 12V source. If it works, great, it is the Battery so you can get a new one knowing that it'll cure the problem.

However, I'm not convinced. 11.7 - 11.8V isn't brilliant but (a) it should still work and (b) that could just be a consequence of it standing around for a while and it may have been higher than that when the fault was triggered.

Looking at the P0A0D in conjunction with the B15F9, it may possibly be a harness or connector come loose at either the multimedia head unit or the inverter assembly:

 

[ColinBarber]

4 hours ago, Ragzv6 said:

I thought as it's not far off 12 then it's OK

The issue is whilst we call a 6-cell lead acid Battery a 12 v Battery, each cell is actually 2.1 v so the total Battery voltage is 12.6 v.

When you measured 11.7 v was there any load, such as side lights on to get a true reading? When you apply a load to the Battery, such as turning on the ignition, then that 11.7 v could drop to 10 v and cause the errors you are seeing.

[Ragzv6]

17 hours ago, Herbie said:

Before spending money on a new battery, just try a set of jump leads and give it a different 12V source. If it works, great, it is the battery so you can get a new one knowing that it'll cure the problem.

However, I'm not convinced. 11.7 - 11.8V isn't brilliant but (a) it should still work and (b) that could just be a consequence of it standing around for a while and it may have been higher than that when the fault was triggered.

Looking at the P0A0D in conjunction with the B15F9, it may possibly be a harness or connector come loose at either the multimedia head unit or the inverter assembly:

 

How will I confirm this test as the car starts and drives fine and the message on the dash only comes on after a couple of days of it being cleared. 

I will look into this and check for any loose connection, as I did go over a pothole which could have jiggled it. 

[Ragzv6]

14 hours ago, ColinBarber said:

The issue is whilst we call a 6-cell lead acid battery a 12 v battery, each cell is actually 2.1 v so the total battery voltage is 12.6 v.

When you measured 11.7 v was there any load, such as side lights on to get a true reading? When you apply a load to the battery, such as turning on the ignition, then that 11.7 v could drop to 10 v and cause the errors you are seeing.

At the time of test the ignition was on with engine off. Only thing on was the head unit. So with the engine running should I be getting a higher reading, so assuming the voltage shows 12.6v with the engine running would this confirm its OK?

[NemesisUK]

The hybrid doesn't have an alternator, so engine running or not shouldn't make a difference? The 12v Battery is recharged by the traction Battery as soon as the car is in the Ready state.

By ignition on but engine not running do you mean you pressed the Power button twice without depressing the brake pedal?

[ColinBarber]

47 minutes ago, Ragzv6 said:

So with the engine running should I be getting a higher reading, so assuming the voltage shows 12.6v with the engine running would this confirm its OK?

In Ready state, whether the engine is running or not, you should expect to see 14.4 v as the Battery will be charging. You may not see the full 14.4 v at the Battery if it is low on charge though but certainly 13+ v.

[Ragzv6]

38 minutes ago, NemesisUK said:

The hybrid doesn't have an alternator, so engine running or not shouldn't make a difference? The 12v battery is recharged by the traction battery as soon as the car is in the Ready state.

By ignition on but engine not running do you mean you pressed the Power button twice without depressing the brake pedal?

Yes that's correct, power button was pressed twice. So I should get a higher reading with the engine on otherwise that will confirm its definately the Battery or can it still show a higher reading when charged but drains soon after....

[Ragzv6]

9 minutes ago, ColinBarber said:

In Ready state, whether the engine is running or not, you should expect to see 14.4 v as the battery will be charging. You may not see the full 14.4 v at the battery if it is low on charge though but certainly 13+ v.

Sure, I will give it another test tonight and see what readings I get.

[Ragzv6]

In ready state its showing 14.3v.

Since I disconnected the Battery and service plug for about 20mins yesterday it hasn't come back. Saying that the last time I reset it, it appeared 2 days later so tomorrow should confirm it. Hybrid blocks also seem fine all at around 15.5v. 

I will do a update tomorrow. 

But if it doesn't appear I assume all is OK.

But if it does reappear then I guess I will need to look into the head units harness and connectors. 

[Ragzv6]

So after about 5 days the light was back but my fuel was low so the next day I went to get some petrol and to my surprise the check hybrid system message disappeared straight after I turned the car back on. So I kept an eye on the fuel and after a week, when the cruising range got to about 50mpg and the needle on the fuel guage got just below the first line the message reappeared again, followed by a low fuel message. So I topped her back up and the message disappeared again. This leads me to believe maybe the float in the tank could be giving an inaccurate reading or one of the connections to the float. What are u guys thoughts and how difficult would this be to get to?

[Herbie]

I don't think they use a float these days, but rather 'calculate' the fuel level and consumption by measuring various parameters such as fuel flow rate, road speed and so on.

I used to have a 2005 RX300 and had it converted to run on LPG, but the fuel gauge would still go down as though it was using petrol when it wasn't.

Just what this means for your particular problem though, I don't know.

[Ragzv6]

On 3/10/2022 at 9:18 PM, Herbie said:

I don't think they use a float these days, but rather 'calculate' the fuel level and consumption by measuring various parameters such as fuel flow rate, road speed and so on.

I used to have a 2005 RX300 and had it converted to run on LPG, but the fuel gauge would still go down as though it was using petrol when it wasn't.

Just what this means for your particular problem though, I don't know.

 

I just watched some videos on YouTube and apparently some models use a level sensor attached to the fuel pump housing which is located under the back seat, so I just need to determine how mine makes these calculations.

I need to ensure its definately the culprit and I'm a bit dubious because the fuel guage and cruising range displayed seem to be moving correctly, wether it is accurate or not is another question which will need investigating. I know its not as economic as it was before I started using the e10 fuel, so will monitor my mpg and maybe switch to premium fuel, but prices right now is a joke £1.70 per litre 🤦🏻‍♂️