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BAD ECU code B2799


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Hi told ecu is toast, have fault B2799, immobilsher issue car starts then chucks it.

If ECU totally gone would I get welcome sign on dash check etc,

was thinking of sending ECU away to get tester, told transponder in key can’t be at fault. said it be a waste of time attempting to get keys reprogrammed.

the fob open closes door light goes off when key in ignition, no fuses blown , just car has shut itself down😩

 

Its a old 2008 and up until now never had any issues.

 

any recommendation in where to send ecu off to test, 

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B2799 is a immobiliser code. yes the chips in the keys can fail, try it with a spare key

in the key, the immobilizer chip is passive and unrelated to the remote door-locking

 

On a 2008, the immobilizer is not part of the ECU, I doubt the ECU is the issue

 

A decent auto locksmith will be able to check the key to see if it is working and program a new one if it has an issue

 

just a few questions

did you or someone else replace the fob case or Battery ?

No one has stuck a decorative ring around the key barrel ?

Has the car had a flat Battery or been jump-started ?

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Tried other key still no joy

believe Battery was flat and possibly jump started😫😫😫 which may of caused ecu to fail

 

bought new Battery still no joy

 

took keys to auto locksmith he said transponders ok

 

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New Battery was put in key at timpsons,

 

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that narrows it down

to the loop around the barrel the immobilizer or wiring

 

the immobilizers use 3 different power circuits and 2 ground points

what engine do you have as diag for diesel and petrol are different

 

do you have any technical skills

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technical skills no afraid but I give it a go , it’s a petrol engine.

Just with being female being told going to cost £££s worth more than it is, maybe it is but I feel  some garages I’ve been to first words are ummm expensive☹️ it’s electrical

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Not sure if had anything to do with it but alarm went off for no reason a month before never ever normally goes off, I put a brand new Battery on and obviously couldn’t run the Battery 2 weeks later the Yuasa Battery was dead

everyone saying has to go to scrapyard heaven

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I very much doubt it is the ECU as you are getting a B2799

Key - Coil/amplifier - Immobilizer - ECU

 

B2799 means the ECU is not talking to the Immobiliser and vice versa or the ecu is not seeing the correct code

check fuses ECU-IG1, AM1, and ACC

 

https://fuse-box.info/toyota/toyota-rav4-xa30-2006-2012-fuses-and-relay

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Guy had his machine and tested all the fuses all seemed ok

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I’m looking to see where they are now but by time I get home will be dark, daft question but as I’m a girl will I be be ok leaving Battery connected.

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IMHO it is probably a good time to get someone in with a diagnostic reader that is capable of recoding keys.                          

If the keys can't be recognised by the reader there will probably be a more serious problem.

Guessing can be expensive. 

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Update went over to locate fuses but get dark for some reason thought wonder if that switch next to sun roof for pets has anything to do with it that you can turn on when locking car never seemed to have worked in past.

Anyway to my amazement car started tried it on off several times all ok was shocked.

let car  and got up to temperature was ok

Goes to start it again , and NOthing  just trying where before it would turn over once then cut out.

 

 

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1 hour ago, GBgraham said:

IMHO it is probably a good time to get someone in with a diagnostic reader that is capable of recoding keys.                          

If the keys can't be recognised by the reader there will probably be a more serious problem.

Guessing can be expensive. 
 

it’s been plugged into dispagnisgjcs and coming up immobilsher b2799

 

 

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You can try to re-match a key if you have checked that all fuses are in order, or you can disable the ecu and see if the instrument has an anti-theft fault light (that is, the light of a key in the car) when you start it.

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Try these people, they are one of the companies I used for my years in business https://allcarelectronics.co.uk/ 

If they have one in stock, they will send you an ECU either with keys or a decoded unit for a hire or to buy if yours is at fault. If the fault is the same you just send it back all it has cost you is the hire fee.

If they don't have one, you can send yours in for test and repair and a probable decode

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2 hours ago, feng71 said:

You can try to re-match a key if you have checked that all fuses are in order, or you can disable the ecu and see if the instrument has an anti-theft fault light (that is, the light of a key in the car) when you start it.


when I put key in ignition the light goes out , weird how car actually started yesterday for first time in weeks. And started on/ off for a few times then decided not to start, wonder if it could be a wire touching,

 

when it wouldn’t start and coming up with b2799 fault on dash it was beeping check brake system, the dash has now gone back to normal first time in 6 weeks, but for some reason won’t start

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35 minutes ago, Helpneeded said:


when I put key in ignition the light goes out , weird how car actually started yesterday for first time in weeks. And started on/ off for a few times then decided not to start, wonder if it could be a wire touching,

 

when it wouldn’t start and coming up with b2799 fault on dash it was beeping check brake system, the dash has now gone back to normal first time in 6 weeks, but for some reason won’t start

Putting the key in and this is putting the immobiliser light out is showing the key has been recognised by the ECU.  I think more information is needed from when it fails to start, as in what does and doesn't happen. I am starting to think you may be having an under load volt drop somewhere and the fault code could be just a red herring because of some power loss.

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1 minute ago, GBgraham said:

Putting the key in and this is putting the immobiliser light out is showing the key has been recognised by the ECU.  I think more information is needed from when it fails to start, as in what does and doesn't happen. I am starting to think you may be having an under load volt drop somewhere and the fault code could be just a red herring because of some power loss.

I’ve just tried it again after being left overnight started left it idle got up to temperature, turned off tried to start again and wouldn’t,

Could plugs be a issue would that show on diagnostics,

 

As rac thought it was flooded  as it had a few good attempts over the weeks trying to start

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13 minutes ago, Helpneeded said:

I’ve just tried it again after being left overnight started left it idle got up to temperature, turned off tried to start again and wouldn’t,

Could plugs be a issue would that show on diagnostics,

 

As rac thought it was flooded  as it had a few good attempts over the weeks trying to start

No it won't be plugs, if it was immobilised you should have no ignition or fuel pump so it shouldn't have flooded. Please pass on engine type so people know what they dealing with. 

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It’s a 2litre petrol 2008, wondering if it could be fuel pump, but when it does start it runs, just if switch off doesn’t want to start again, would a fuel pump show on diagnostics. 
 

I rang one garage today and he said without be cheeky are you sure the  engine was  running patronising or what🥺 just cos I’m female and not a mechanic I know when engine running , I said yes got bonnet up and belts are moving😀

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In short no for the fuel pump. You haven't given the engine code (type) so can you tell me if it's coil on plug or coil with distributor? I will be surprised if it's the later.

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if it intermittently starts then sometimes you get the B2799 it's not a key, ring, or ECU issue - its a power or ground problem with the immobilizer

 

Just to clarify the Imobolizer and ECU are separate modules

2008 is coil on plug Toyota stopped using dizzy's early 00

2.0 petrol on a uk car will be a 1AZFE, the valvematic 3zrfae didn't come in till 09

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1 hour ago, flash22 said:

if it intermittently starts then sometimes you get the B2799 it's not a key, ring, or ECU issue - its a power or ground problem with the immobilizer

 

Just to clarify the Imobolizer and ECU are separate modules

2008 is coil on plug Toyota stopped using dizzy's early 00

2.0 petrol on a uk car will be a 1AZFE, the valvematic 3zrfae didn't come in till 09

If the immobiliser light goes out then the key is recognised so the crank sensor could quite easily be at fault? One thing for sure it can't be cured on here especially with not getting more info.

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op has the code B2799, not a cam or crank code, going with numerous other examples and data this is likely to be an electrical issue with the immobiliser

there are 2 causes 3 powers to the immobilizer or it is ground-related, B2799 can be caused by the ground the coils use on the head this is also related to the DLC ground

 

yes someone has shot the parts cannon at it already

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