Do Not Sell My Personal Information Jump to content


IS300H Electrical gremlins (car thinks its still on when ignition is off)


Recommended Posts

Hi all,

I've been a long time lurker of this forum, but im now in need of help with a strange issue. Owned the car for a year and a half with no issues until this weekend gone.

1. Got home one night and locked the car as normal and went to bed, I was then woken up by the alarm going off.

2.Turned it off but it proceeded to do it 4 times that same night, then I noticed (on the last alarm sounding) that the key would not lock or unlock the car. Took the negative battery terminal off(had to use the physical key to get in the boot) and all was good, or so I thought!!

3. Put the battery back on and even though the car had been off all day, the car said ''key not detected''. The climate control was also running as was the headlights(set to auto mode). So the car thinks the ignition is still on?

 

The car still starts and drives with no lights or errors on the hybrid system. Its just that the key will not remotely lock or unlock the car (same with spare key) and all these systems were still on even after pressing the stop button.

I'm sure its a short circuit somewhere but im at a loss of where to start looking as these cars are not known  for these kinds of issues.

Also, if this helps; when i start the car by pressing the start button i hear two distinct 'clunks' or 'clicks' that sounds like its coming from the high voltage battery underneath the boot. Which was not there before all these issues started.

Any help would be appreciated.

Thanks, 

Josh

 

Link to comment
Share on other sites


Low 12v battery seems to be the cause of many gremlins.

Worth testing the battery and replacing it. Or at least giving it a good top up with a trickle charger if it is not too old / defective.

Watch out for killing your radio when disconnecting the 12v and / or switching the 12v for a new one. Documented issue on these forums, very expensive fix.

Link to comment
Share on other sites

I agree with Matt - 12V battery failing. This can cause all sorts or weird gremlins to appear.

Go to a garage or even car accessory shop like (urgh) Halfords and ask them to load test it. If you put a multimeter across it you may well see 12V but if any load is put on it, that voltage may drop like a stone.

Link to comment
Share on other sites

I tend to agree regarding the 12V auxiliary battery, the clunks you hear are the HV contactors being energised and if the 12V battery is low charge they will not pull in cleanly resulting in excessive arcing across the contacts which can lead to them being stuck.

Faults on these however normally flag a fault code.

Go for the battery test first as advised and replace if required, it has been mentioned that Lexus were the cheapest source for a replacement so maybe worth contacting Derby Lexus.

 

Link to comment
Share on other sites

3 hours ago, matt8 said:

Low 12v battery seems to be the cause of many gremlins.

Worth testing the battery and replacing it. Or at least giving it a good top up with a trickle charger if it is not too old / defective.

Watch out for killing your radio when disconnecting the 12v and / or switching the 12v for a new one. Documented issue on these forums, very expensive fix.

Can you provide the link to the killing the radio when changing battery?

Link to comment
Share on other sites

Thanks for the quick replies i appreciate it. 

So i had a look at the battery, the date code on it is MAR 2020 so its quite new. I tested the voltage and it was coming up as 12.64v. But i did take it out and put it on a trickle charger for about 7 hours. Unfortunately this doesn't seemed to have helped.

1. The car still thinks its on when its not, and now even stranger; when i put the light switch to fully off (from auto) the daylight running lights still stays on. Before when i did that all lights went off. The climate control stay on also, however the head unit is now turning off.

2. I scanned the car with techstream (on a really bad laptop btw) and it does not show any issues; except for the loss of communication on most modules when i unplugged the battery before. I think that's the case as all the timestamps for the ''communication errors'' are all at the same time.

 

I have booked the car in for a check up on monday at lexus. However im still open to any ideas because i know im missing something. I hope its not something drastic as ive just spent a fair bit on 2x new bearings, 2x reconditioned front calipers and some other suspension bits(no fault of the car, i was just an idiot and bent the tie rod by reversing into a bollard, bearings were on the way out also at 72k miles).

Link to comment
Share on other sites

Certainly a weird issue. I assume the vehicle hasn't been tampered with, e.g. someone tying to disable the alarm/break in via wiring in the engine bay?

Ignition being on, possibly a problem with the power management ECU or a relay somehow is stuck on.

  • Like 1
Link to comment
Share on other sites

14 hours ago, Josh86 said:

I tested the voltage and it was coming up as 12.64v

Is that with it disconnected from the car and off?

What voltage reading do you get when the car is connected and on? Should be 14.4V or so.

Link to comment
Share on other sites

Yea the car doesn't seem to have been tampered with at all, which was my initial thoughts as well. I'm also inclined to believe its a power module or relay somewhere but that's out of my depth I think (my brain switched off when I read there are two ECU's and two fuse boxes lol). 
With regards to the battery voltage when the car is running it moves a bit between 14.62 and 14.59 but that seems mostly normal.

The car has been at the mechanics since Monday, ive never seen a more bewildered look on the tech's face as I described the issue to him. Definitely not an everyday or common issue I think. He suggested there could be an problem with the physical start/stop button and would take a look at that.

I haven't received any phone calls since I dropped it off and I cant help but feel like its gonna be very expensive to diagnose and fix. Ill keep you updated anyways on the outcome.

Link to comment
Share on other sites

On 3/25/2022 at 12:46 AM, Josh86 said:

Yea the car doesn't seem to have been tampered with at all, which was my initial thoughts as well. I'm also inclined to believe its a power module or relay somewhere but that's out of my depth I think (my brain switched off when I read there are two ECU's and two fuse boxes lol). 
With regards to the battery voltage when the car is running it moves a bit between 14.62 and 14.59 but that seems mostly normal.

The car has been at the mechanics since Monday, ive never seen a more bewildered look on the tech's face as I described the issue to him. Definitely not an everyday or common issue I think. He suggested there could be an problem with the physical start/stop button and would take a look at that.

I haven't received any phone calls since I dropped it off and I cant help but feel like its gonna be very expensive to diagnose and fix. Ill keep you updated anyways on the outcome.

Fingers crossed for you, will be interested to know the outcome 🙂

Link to comment
Share on other sites

On 3/25/2022 at 12:46 AM, Josh86 said:

The car has been at the mechanics since Monday

Probably better taking it to a proper auto electrician rather than a mechanic - mechanics for mechanical things, sparks for sparky things.

Link to comment
Share on other sites

  • 1 month later...

Ok so after 4 weeks of being at the garage the car is back now and working again! Just going to post what happened so it helps other people in the future.

So after I sent the car to the garage, they were looking at changing the start button on the dashboard. Turns out this didn't fix it as the 12v battery was dead the next day. Then they started pulling fuses to see if it helped. Pulling the ECU 2 (the body control ECU) fuse turned seemed to do the trick and the radio/ac/lights went off. Plugging it back in brought the issue back. 

So they phoned me and told me that and quoted me £1050 for that ECU alone :(. They then left the car overnight with the fuse off but this still killed that 12v battery again, and they were sure that it was something else(even after replacing the ecu with a new part so they put the old one back)

After a few weeks of head-scratching and basically getting nowhere, the car decided to drop a hint of where the issue was by activating the headlight washer and emptying about 3 litres of washer fluid all over the shop floor. This was a bit suspicious so they looked closely at the headlight washer and pump assembly and PRESTO!!! The Ecu controlling the headlight washers(different to the windscreen washer ECU) had basically had a short circuit, and made the washer pump run 24/7, which also burnt out the motor in the pump when it ran dry. Was quoted £700 just for those two parts to fix it(and it was very fishy that they had the parts in shop already) so I just said **** it and they unplugged that whole assembly and the car has been fine since I got it a few days ago. I think I will wipe the headlights clean myself rather than pay £700 for the stupid headlights to get a stupid spray on them.

 

All in all it was about £500 plus vat for the diagnosis including a new battery as the 'old' battery had died being discharged about 10 times during the last 4 weeks. Basically the issue was with the headlight washer ecu and assembly, and im grateful to them for finding it cuz I would not have in a million years thought it would be something so simple yet so frustrating to find. 

Anyways, I hope it helps someone out there who comes across this issue in the future, start pulling out fuses and if it is the body control ecu 2 start looking at what is connected to that ecu, especially the headlight washers as Lexus having the parts on their shelf already means its probably a more common issue with these basically bullet proof cars. 

Going forward, I think its time for me to sell this car as much as I've loved it. Its appreciated in value quite substantially since I got it and with a baby on the way, I cannot justify spending at least £500 every time ive had an issue with it(like 5 times already). will settle for a cheap Honda until I can come back to Lexus and own my dream car, the LC 500.
Thank you all for your help in trying to find this issue for me and I hope it proves useful to someone in the future 🙂

All the Best,

Josh

  • Thanks 3
Link to comment
Share on other sites

5 hours ago, Josh86 said:

Ok so after 4 weeks of being at the garage the car is back now and working again! Just going to post what happened so it helps other people in the future.

So after I sent the car to the garage, they were looking at changing the start button on the dashboard. Turns out this didn't fix it as the 12v battery was dead the next day. Then they started pulling fuses to see if it helped. Pulling the ECU 2 (the body control ECU) fuse turned seemed to do the trick and the radio/ac/lights went off. Plugging it back in brought the issue back. 

So they phoned me and told me that and quoted me £1050 for that ECU alone :(. They then left the car overnight with the fuse off but this still killed that 12v battery again, and they were sure that it was something else(even after replacing the ecu with a new part so they put the old one back)

After a few weeks of head-scratching and basically getting nowhere, the car decided to drop a hint of where the issue was by activating the headlight washer and emptying about 3 litres of washer fluid all over the shop floor. This was a bit suspicious so they looked closely at the headlight washer and pump assembly and PRESTO!!! The Ecu controlling the headlight washers(different to the windscreen washer ECU) had basically had a short circuit, and made the washer pump run 24/7, which also burnt out the motor in the pump when it ran dry. Was quoted £700 just for those two parts to fix it(and it was very fishy that they had the parts in shop already) so I just said **** it and they unplugged that whole assembly and the car has been fine since I got it a few days ago. I think I will wipe the headlights clean myself rather than pay £700 for the stupid headlights to get a stupid spray on them.

 

All in all it was about £500 plus vat for the diagnosis including a new battery as the 'old' battery had died being discharged about 10 times during the last 4 weeks. Basically the issue was with the headlight washer ecu and assembly, and im grateful to them for finding it cuz I would not have in a million years thought it would be something so simple yet so frustrating to find. 

Anyways, I hope it helps someone out there who comes across this issue in the future, start pulling out fuses and if it is the body control ecu 2 start looking at what is connected to that ecu, especially the headlight washers as Lexus having the parts on their shelf already means its probably a more common issue with these basically bullet proof cars. 

Going forward, I think its time for me to sell this car as much as I've loved it. Its appreciated in value quite substantially since I got it and with a baby on the way, I cannot justify spending at least £500 every time ive had an issue with it(like 5 times already). will settle for a cheap Honda until I can come back to Lexus and own my dream car, the LC 500.
Thank you all for your help in trying to find this issue for me and I hope it proves useful to someone in the future 🙂

All the Best,

Josh

Many thanks Josh for the update, I had a Honda accord which was very reliable so I'm sure you'll be happy with one 🙂

Link to comment
Share on other sites

You mention 5 other issues you've had, @Josh86

What were they if you don't mind us asking?

If I had 5 prior issues I'd be feeling the same!

Link to comment
Share on other sites

Thats such a shame Josh, but Marks right you wont go wrong with a honda to save and get some cash together as they are bombproof.

Rob

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share



  • Join The Club

    Join the Lexus Owners Club and be part of the Community. It's FREE!

  • Topics

  • Our picks

    • 10 years of Lexus design: from spindle grille to spindle body
      After 10 years as a defining style feature of every new Lexus model, the famous spindle grille is undergoing a transformation. In tune with a new era of electrified vehicles, the distinctive shape is evolving into a new “spindle body,” as seen on the upcoming new generation Lexus RX SUV and the all-electric RZ.

      The spindle grille has been an unmistakeable Lexus feature since it was first revealed on the LF-Gh concept model of 2011, the basis for the fourth generation GS executive saloon that was launched the following year. Since then, it has been constantly adapted to suit the character of each successive Lexus model, with different mesh patterns, dimensions and finishes.


      Speaking at the time of the grille’s debut, the then Head of Lexus Kiyotake Ise said: “You should be able to identify a car as a Lexus immediately… Instant visual recognition, for example, is the reason behind our spindle grille. It may look aggressive at first glance, that’s intentional, but it also conveys its boldness with sophistication and elegance.”


      It has progressed to become a hallmark expression of Lexus’s L-finesse design, adopted not only for road-going cars, but also incorporated in the futuristic Skyjet spacecraft created for the Lexus-supported movie Valerian and the City of a Thousand Planets and adopted as a design motif in the Loft, the award-winning Lexus and Brussels Airlines lounge at Brussels Airport.


      Today, the original grille concept is the starting point for a more radical application of the spindle shape in which it becomes an integral part of the vehicle’s overall design. This “spindle body” approach is part of the Lexus Next Chapter design for the all-new RX, where the grille is reinterpreted as a seamless unit that flows into the bodywork. The lower section retains a mesh pattern, while the upper section takes in the lower edge of the bonnet; the Lexus emblems sits at the centre of the spindle’s high pinch-point.


      The same concept has been applied to the RZ 450e. As a battery electric vehicle, this requires less cooling than a car with a conventional engine, so the grille has been dispensed with, giving the designers greater freedom. Nonetheless, the spindle shape remains prominent in a central front panel, finished in the car’s body colour. Its impact is heightened by the adjacent frontal areas being contrast-finished in black, the low bonnet line and more boldly shaped front wings.

      On both models, the spindle generates lines that flow back from the front of the car through the bonnet and headlamp units to create a strong and distinctive frontal appearance, reinforcing the brand-defining ambitions of the original concept.
      • 0 replies
    • Lexus joins the UK’s Motability Scheme with the new UX 250h F Sport Design
      From this week, people with mobility needs will be able to access a Lexus vehicle through the UK’s Motability Scheme
      • 0 replies
    • All-New Lexus RX to star at the Venice International Film Festival
      Festival to attract world-renowned actors, celebrities and creatives to the Lido di Venezia from 31 August to 10 September 2022
      • 0 replies
    • The all-new Lexus RZ: powerful design rooted in electrified performance
      Lexus maintains its status as a design innovator in creating a radical look for its all-new, all-electric RZ that directly interprets the SUV’s power and performance
      • 0 replies
    • Lexus guide to interesting EV charging locations off the motorway
      With the Great British holiday getaway on the horizon, drivers of BEVs (battery electric vehicles) will be considering where to recharge on their journey.  While motorway service stations are an obvious choice, Lexus has researched some more interesting alternative locations
      • 0 replies


×
×
  • Create New...




Forums


News


Membership