GS450h - Brake Lights On

[Odysseus]

My rear brake lights, including the centre light in the rear window are all on and cannot be switched off. Even when the car (like now) is sat parked, locked, and generally powered down.

 

The car drives otherwise normally, there are no warning lights on the dash or messages of impending disaster. Economy seems unaffected so I’m satisfied the actual brakes are not on. The cruise control doesn’t work in either radar or normal mode. Presumably because braking normally turns cruise control off.

 

The brake lights seem unaffected by actual braking, acceleration, or indeed anything. To anyone following me it looks as if my brakes are just on constantly.

 

The only reasonably unusual thing that happened is I had to brake sharply on the motorway today. This did activate the pre-collision and brake assist but it was all over in a few seconds and I carried on my merry way. I wonder however if my lightning fast, ninja fighter pilot reflexes have confused something (brake pedal switch?) which is causing this weirdness.

 

I’ve booked the car into Lexus Cambridge later this week for them to take a look, but any suggestions in the meantime would be gratefully received.

 

 

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[Farqui]

This has just started happening right?

Take a look at the switch on the brake pedal, maybe it needs adjusting? They often have a lock nut and can be wound out a turn or two before nipping the lock nut back up.

Or to check if the switch is faulty, try unplugging it and see if the brake lights go out.

Will be interested to hear what the issue is and how it's resolved.

Good luck.

[Farqui]

Sometimes the switch plunger sits on a plastic stop that can occasionally work loose. Have you recently found any odd bits of plastic in the drivers footwell?

[Upex]

My money is on that switch, just as Farqui says.

Braking very quick can also lodge crap between plunger and it's recess, thus trapping the plunger in the retracted position and thus leaving the lights on.

I'm not sure though if the light circuit is powered when car off and shut, powered down completely though. If they are, then above still works. If not, then I suspect a short somewhere, allowing power from another circuit to flow through the brake circuit even if switch is not pressed.

Start with the switch though, much easier lol

[stevet]

My money is on the switch. I'm sure the brake lights work without the ignition on.

[Odysseus]

Thanks gents, I think you're all on  the money with the switch.

Current problem is a bit more immediate.  The ****ing thing won't start.  Clearly having the brake lights on all night has flattened the Battery.  Dead as a door nail.

At the moment I'm sat at home waiting for the AA man to arrive.  Lexus warranty and recovery proving useful...

[Farqui]

Doh, how annoying.

While you're waiting you could take a look at the switch 

[Odysseus]

All sorted. The AA man duly turned up, faffed about under the bonnet looking for a way to jump start the car before managing to power up the fuse box, which allowed him to open the boot, which allowed him to get to the Battery, which allowed him to start the car.

He then brought his skills and spanners to bear on the brake pedal switch, and has adjusted it. which was apparently all out of alignment and not working properly.

As it stands the car is working normally; brake lights not on (unless I’m braking), cruise control working, and everything peachy.

I’ve cancelled the appointment with Lexus tomorrow.


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[Farqui]

Excellent news, well done mr AA man.

Interesting point about no power to the 12v Battery, isn't there a key option to access the boot? - slopes off to Google...

[stevet]

Yes, there is a key slot just near the normal hand pad. But as it's soft closing it might still need electric.

[Farqui]

I thought it did (says so in my e-copy of the manual), like this; 

Reference; https://www.clublexus.com/forums/ls-4th-gen-2007-2017/519045-emergency-trunk-opening-procedure.html

[OldTrout]

Lee,

Did this key slot come in with the 2008 model them? My 2007 does not have it.

John

[royoftherovers]

21 minutes ago, OldTrout said:

Lee,

Did this key slot come in with the 2008 model them? My 2007 does not have it.

John

Nor does my 2010 have it and there is no mention of it in the Handbook.

 

Regards

John

[Farqui]

Really, it's on the left hand/nearside of my boot lid. 

It wasn't initially obvious it's there as it's thoroughly covered in black goo.

[Upex]

Glad you sorted it Andrew, although I'd have pulled some fuses or disconnected Battery if they'd be stuck on before leaving any time, to save that faffing!

 

I have the key hole, I think, on a 2006, will have a look. Seems stupid to not have it when Battery in boot, unless there a manual release elsewhere? Like the little pull cords that are behind trim panels etc. Be crazy if it closed with no Battery installed, or when disconnected, be stuck forever then as couldn't get power in via anywhere else if no circuit to be made.

Are these cars common ground or common positive? Assume the former, but not done anything to establish it yet.

[stevet]

13 hours ago, Upex said:

 

I have the key hole, I think, on a 2006, will have a look. Seems stupid to not have it when battery in boot, unless there a manual release elsewhere? Like the little pull cords that are behind trim panels etc. Be crazy if it closed with no battery installed, or when disconnected, be stuck forever then as couldn't get power in via anywhere else if no circuit to be made.

 

It's only the 450's that have the Battery in the boot so wonder if the boot locking is different on them?

[Chris111]

Just to add my twopence worth I have opened the boot of mine with my key using this lock when I experienced a flat Battery. It is to the left of the left number plate light unit. The picture posted by Lee above shows it in the location that houses the camera on right hand drive models.

[Farqui]

4 minutes ago, Chris111 said:

Just to add my twopence worth I have opened the boot of mine with my key using this lock when I experienced a flat battery. It is to the left of the left number plate light unit. The picture posted by Lee above shows it in the location that houses the camera on right hand drive models.

Good to know Chris, thanks.  

The more eagle eyed observers will note that my pic was from the LS with the boot key on the RHS.

I couldn't find a pic of the key on the GS 450H, note to self; must try harder...

[OldTrout]

Yes I have it now. Camouflaged by some black stuff.

It does work but when I turn the key I hear the motor whirl so would this work if the 12V Battery were flat?

John

[Chris111]

I should also add the instruction is on page 457 of my owners manual.

[Chris111]

1 minute ago, OldTrout said:

It does work but when I turn the key I hear the motor whirl so would this work if the 12V battery were flat?

Yes because I have done it.

[stevet]

2 hours ago, OldTrout said:

Yes I have it now. Camouflaged by some black stuff.

It does work but when I turn the key I hear the motor whirl so would this work if the 12V battery were flat?

John

Exactly my thinking.

[Odysseus]

Given it was my issue that started this discussion, the least I can do is show a picture of my key access to the boot.



The AA man’s databanks apparently didn’t know the GS came in hybrid form hence why he had some of the challenges he did.

Either way, all’s well that ends well.


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[Chris111]

1 hour ago, stevet said:

4 hours ago, OldTrout said:

Yes I have it now. Camouflaged by some black stuff.

It does work but when I turn the key I hear the motor whirl so would this work if the 12V battery were flat?

John

Exactly my thinking.

For info page 457 of the GS 450h owner's manual instructs to open the boot this way if the keyfob Battery has discharged and page 459 also instructs to open the boot this way to access the 12 volt Battery if that has discharged. As per my previous post I have done this so I know it works.