DRCC Fault -fails to regain speed

[2Nick]

I have a 2023 Icon 1.8 Hybrid Tourer. The DRCC works fine when tracking vehicles ahead moving at a relatively constant speed.

If the vehicle ahead slows enough that DRCC has to slow my vehicle by decreasing the throttle into the charge mode it then just goes to "idle" and does not increase speed when the vehicle ahead speeds up. If I do nothing my vehicle just slows as if its just idling. If I quickly tap of the accelerator peddle it restores normal behaviour and the car speeds up to the set speed and maintains it as expected.

It also shows the same behaviour when descending hills, if the DRCC slows the vehicle when you reach the bottom of the hill the vehicle fails to accelerate and would coast to a halt if I did nothing, again a small tap of the accelerator peddle restores normal behaviour and the car speeds up to the set speed and maintains it as expected.

I have been to the dealers and they could offer no solutions and checked all settings.

I took out their demonstrator and this worked perfectly I spent 2 hours trying it where my car would have misbehaved and the demonstrator coped with all scenarios.

I would also add that I had a 2019 hybrid tourer for the previous 4 years which worked perfectly so I am used to how the system is supposed to work.

Any one else seen this behaviour?

[Cyker]

Can't say I have, although I usually disable the DRCC when traffic ahead slows because mine handles it really badly, so I don't have as much experience.

Maybe the system needs a firmware update?

What following distance have you set? Does it change the behaviour if you set it to minimum distance vs maximum?

[2Nick]

Ive tried all the distance settings and been through all the other Safety Sense settings like PDA etc turning them on off with no change.

When tracking correctly it works very smoothly as did our previous corolla which makes this all the more obvious and dissapointing.

Im thinking a software bug or an intermittant conection , badly aligned or loose camera, it seems to be set very low in the apparture We had one instance for about 30mins when it seem to work ok but then went back to this behaviour when restarted.

 

 

[Cyker]

Hmm, can you compare the camera position to another car? Maybe it had a new windscreen but the ADAS pod wasn't fitted properly or it wasn't re-calibrated?

It would also be worth getting them to update it all to the latest firmwares just in case - It may have been accidentally reset to the original at some point; A user on here had that happen to them which caused their 12v Battery to drain and they missed this several times before someone there finally thought to check the versions.

 

[2Nick]

yes I think thats a good idea. unfortunately the dealer I bought it from is losing thier Toyota Franchise this month and isn't really interested. They assure me they will do do a handover so hopefully the new dealer will play ball.

going to disconnect the 12v Battery this weekend and hopefully reset and restart everyhing -the good old switch off switch on again! ... you never know

.

[JasonM]

Some while ago Nick but did you ever resolve your problem as I have the exact same issue?  

[2Nick]

2 hours ago, JasonM said:

Some while ago Nick but did you ever resolve your problem as I have the exact same issue?  

Hi Jason yes  the new dealer (Snows in Poole) had Techs who were good, willing to talk and work it through. It turned out to be the Accelerator pedal  assembly I believe there was intermittant contact on the position sensor. I found putting  side pressure on the pedal briefly would make it work until I switched off the car. I could stop it working by a quick kick of the  pedal in opposite direction.

They swapped out throttle pedal assembly  ... problem solved!

 

 

[JasonM]

That’s interesting Nick many thanks for picking this up again.  I thought it would be more likely to be the brake pedal position sensor if it was interrupting the cruise control and hadn't considered the accelerator pedal sensor.  I have taken my car to the dealer once already but made the rookie mistake of letting them take the car out themselves and they saw no problem.   I will take it back again and demonstrate the problem myself as seems easy to induce the faltering of the cruise control catching up a slower car running downhill.  I wonder if it’s gravity acting on the pedal that means the issue is mostly downhill, I will experiment by trying to lift the accelerator pedal whilst on cruise control and driving down a gradient.   Thanks again.

[Cyker]

Thanks for letting us know; I'm impressed they were able to diagnose something like that as it sounds quite obscure!!

 

[Jorijn]

On 4/1/2024 at 12:54 PM, 2Nick said:

Hi Jason yes  the new dealer (Snows in Poole) had Techs who were good, willing to talk and work it through. It turned out to be the Accelerator pedal  assembly I believe there was intermittant contact on the position sensor. I found putting  side pressure on the pedal briefly would make it work until I switched off the car. I could stop it working by a quick kick of the  pedal in opposite direction.

They swapped out throttle pedal assembly  ... problem solved!

 

 

Hi 2Nick.

I'm trying to reproduce this issue. Towards what side of the pedal were you pressing to "fix" it?

Thanks!

[2Nick]

Hi Jorijn

I was suprised that it was the pedal assembly. Honestly I discovered it when i got frustrated after it cut out for the umpeenth time. I stomped on the pedal several times and it behaved for the rest of the journey.

I experimented a bit more and found that if I was cruising along, I pushed the pedal from left to right at 90 deg to normal use, engaged cruise it would operate normal for rest of journey.

If I pushed pedal right to left the cruise control would not accelerate once it had slowed significantly.

The car is now working well since they changed the pedal assembly and has not shown this fault again over several thousand miles.

[Jorijn]

Hi 2Nick. Thanks a lot for your detailed description. I'll do some experiments in the upcoming days. If you had to cancel ACC during the trip after it behaved normally, did you have to re-press from the side to the right before activating ACC again for it to keep working normally?

[2Nick]

Hi Jorijn Yes had to press every time before engaging ACC

[Jorijn]

Thanks. Did they explain how this sensor relates to the described behavior? Any information is welcome. 

[2Nick]

No I don't think the dealer knew anymore than us.

The technician was helpful and willing to listen, we proved it was the peddle between us - its a simple job to replace so changed it - it worked - they had no more info on it.

I can only suspect a poor switch contact or intermittant track on the position sensor I've worked with similar stuff but its only a guess

[JasonM]

I have my 23 Corolla TS going in to be looked at for the 3rd time but this time with a Master Technician on Thursday.  I get exactly the same end symptoms as 2Nick (Thanks Paul for past help) but don’t seem to be able to influence them at all by putting pressure on the accelerator pedal side to side in either direction.  I still think it could be a pedal related problem though as seems effected by deceleration or declines so might be losing a contact under these conditions intermittently.   Not sure it can be a software glitch as surely the ECU’s are all programmed with exactly the same code.   I will let you know how I get on….

[2Nick]

Hi Jason good luck

If they won't listen to you maybe they could contact Snows in Bournemouth and speak to Neil the technician who fixed mine (dont have a Surname but its only a small dealer and they all know him)

[JasonM]

Thanks, will do.  I won’t back down on this with Toyota as consider it a dangerous fault if you can without warning lose all power. 

[JasonM]

Just to add to this post I fixed my adaptive cruise control fault by following the helpful feedback from 2Nick and replaced the accelerator pedal.  Although I didn’t have the same symptoms as 2Nick where I could influence the problem by pushing left and right on the pedal, so had my doubts.

Having had no luck with Toyota after 4-5 visits I ordered a Toyota Corolla 2022 accelerator pedal from a breaker off eBay for £50 and fitted it myself.  Took the car out and hey presto  problem solved and cruise control works perfectly and does not switch off when slowing catching up slower vehicles.   I understand this is a very rare fault so kind of understand why Toyota struggled with fixing it but disappointed they disregarded my suggestion to look at the pedal.
 

The pedal has two Hall effect sensors that provide a voltage output even when your foot is off the pedal and I imagine this is needed as part of the DRCC control system.   I could not dismantle the faulty pedal as it’s sealed by suspect a sensor is loose and contact is lost on downhill gradients when slowing down.   Anyway took 5 months to fix but all sorted now so very happy.

[Cyker]

Thanks for letting us know how you get on  

This really sucks though - The fact that they couldn't even diagnose the fault despite you providing strong hints as to the problem and despite them being supposed experts just reinforces my experiences of their diagnostic abilities (i.e. non-existent)

I wonder how this works with warranty, as I feel they really should reimburse you, at the very least the cost of the pedal, since this really should have been covered under the warranty. Maybe e-mail Toyota UK directly to explain the situation, express your dissatisfaction at the level of service received, and that you had to take the repair into your own hands, see if you can get some reimbursement or a free service or something out of it.

 

[JasonM]

I agree, but they are the only Toyota garage near me and feel better to save them the embarrassment.    I’me sure they won’t reimburse me and might even say I’ve invalidated the warranty by doing it myself.   The most important thing is my cars fixed and feel happy to drop it, but like you I think unless it’s a basic oil change service not convinced they have technical skills to diagnose complex intermittent faults.  

[Cyker]

Yeah, which is a pain as it greatly lowers the value of the Relax warranty if they're incapable of diagnosing the problem in the first place...!