00812 brake pressure regulator solenoid

Jayw13702

Member
Finally bled the brakes on the project A2 today, fired up the car and the abs and asr lights were on.
Plugged Vcds in and it gave me 00812 brake pressure regulator. Looking at Ross-tech it lists the following:

Possible Causes

Switch for Brake Recognition (F83) faulty

Wiring to Switch for Brake Recognition (F83) faulty

Brake Booster faulty

The brake lights work so that seems to eliminate the first and second faults and the brake servo (booster)appears to be working fine.
Any suggestions, I’ve tried resetting the fault code and it comes straight back


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audifan

A2OC Donor
Try this. Carefully drive the car round the block while turning the steering in both directions and braking normally. When you get back rescan the car. Sometimes the interconnected modules need to relearn each others positions and this is done by driving the car. Does not always work especially if another fault has been detected but sometimes solves the problem. Recheck ALL brake lights work properly not dim or flickering.
 

Jayw13702

Member
Try this. Carefully drive the car round the block while turning the steering in both directions and braking normally. When you get back rescan the car. Sometimes the interconnected modules need to relearn each others positions and this is done by driving the car. Does not always work especially if another fault has been detected but sometimes solves the problem. Recheck ALL brake lights work properly not dim or flickering.

I could struggle with this as currently it has no MOT and our neighbours are a bunch of little hitlers, they have asked if I am running a business just because I am fixing the car
We may have to get it lifted/trailered to a bit of private land where we can use it without risking the police being involved.

The brake lights are all good, no flickering, dimming or any of them out. This error has only started since I overhauled the brakes and re-bled them
 

audifan

A2OC Donor
As said the drive may reset or the brake switch could be arcing. Drop in another OEM brake switch in the mean time. Do you have good axle stands?
 

Jayw13702

Member
As said the drive may reset or the brake switch could be arcing. Drop in another OEM brake switch in the mean time. Do you have good axle stands?

I was thinking of putting the car on the stands to see if that would help


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audifan

A2OC Donor
How good is the battery voltage and alternator. Sometimes strange errors are caused by under voltage. If battery not been used for a while do a complete charge off the car. Also worth disconnecting the battery and touching the 2 BATTERY CABLES together to clear down the cars electrical system.

You can take the brake switch off and check it cleaning as needed but may be better just replacing it.


Now this is something I normally would NOT recommend, but at your risk and taking as many precautions as possible...
Jack the front of the car and place axle stands under the wishbones mount. Remove both front wheels and firmly block both sides of the rear wheels very well. Start the car and CAREFULLY engage 1st then second now carefully turn the steering as if you were driving and brake. Do this for a couple of minutes ( remember the rear wheels are not turning so ABS not getting complete signals ). Note any warning lights on the dash. Stop car turn off etc.
 

Jayw13702

Member
The battery is brand new and whilst it’s been off the car recently while the rear axle was overhauled it was put on charged before it went back on just to be sure.
The alternator I’m not so sure about, I have seen the interior light flickering whilst the car is idling, however a voltage check at the alternator shows 14.4v .


I may try putting the car on axle stands and putting it in gear, I know it carries risk but it may also cure the issue. I will replace the brake light switch and see if cure the problem as well.

Thanks for your help
 

audifan

A2OC Donor
One other thing you could check when up on axle stands is the condition of the ABS wiring down the front struts to the sensors and the sensors themselves. Do not know what wheels are / have been on the car so possibility the ABS cables have been damaged.

Bad example of cable wear....

794.jpg
 

Jayw13702

Member
I checked them when I had the front brakes apart and they all seemed good.aside from this which I believe is the pad wear sensor and has been like that since before I got the car

bc4bba2905ee05bc97a52c3630fbeba8.jpg



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Jayw13702

Member
I took a video of VCDS running thought some of the measuring blocks today, I can post it up here but I have grabbed some screenshots.

the speed being picked up by the abs sensor, the car was on axle stands and in gear, hence the rears reading zero
6.jpg

this is a pressure reading from the the servo vacuum pipework, does anyone know where this sensor is located?
2.jpg


The steering angle sensor readings
4.jpg


the first 'activated' is the brake light switch, my foot was on the pedal, the second is the handbrake warning light I believe
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Jayw13702

Member
Finally sorted, although not entirely sure what cured it!!

Fitted a new brake light switch, still had the same error code.

Decided to have a look at the pressure switches on the master cylinder and servo, took each one off, cleaned them up and put them back on, this created a load more error codes and a lot of frustration on my part, so I walked away for a while.

Came back to it half an hour later started the car and all the warning lights went out!!! Plugged in VCDS and there were no error codes.

The possibility is that by disconnecting all the sensors I have reset it all and it will now relearn its parameters

Many thanks to @audifan for all his help 👍
 
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