Brake position sensor

[drone]

What effect does the brake position sensor have on the performance of the turbo in a 2006 d5 t4 v70 which has the electronic turbo vane controller?

[davebb]

I don't think it will have anything to do with the turbo, why do you ask?
Dave

[drone]

The car still has high boost pressure and the only fault showing is the brake position sensor, running the data whilst driving shows the boost control (the electronic motor on the turbo) switching between 5 and 100% with immediate effect as it were so the old ecu is going into limp mode to cut the boost.
I have a spare controller but it's pointless fitting it if it's the brake sensor causing the problems. Incidentally it's the one fitted to the servo not the brake light switch.
The output of the turbo bears no relation to the demand issued by the ecu except when I have the brake on when they both coincide.Car is auto btw.

[petey]

VW group vehicles, among others, cut boost when the brake pedal is applied, (which wakes you up if you drive automatics with two feet, using the brake to smooth out take off) but I don’t ever recall losing boost on my ‘05 D5 when I’ve operated the brakes whilst driving. I’m pretty sure the brake position has no effect on boost pressure, at least on mine.

[davebb]

so do you have vida, if you do watch the VNT actuator and make it work with vida, if it is not moving the full way, I would say it may need the vnt turbo cleaning, you do need to see if the actuator is working without the turbo as if the turbo is jammed, the teeth on the gears can brake in the actuator ,
Dave

[drone]

I've disconnected the lever on the turbo servomotor and the vane control runs smoothly through the full range, don't have vida as son has gone on holiday with his laptop(!) and I'm using an iCARSOFT one which is pretty good except it's not possible to test the various servos with it.
The inlet boost pressure sensor is working as the pressure varies between a vacuum and 3000kPa, all the temperature sensors appear to be working as does the egr system.

[drone]

Well it wasn't the brake position sensor, even though that's throwing up a dtc, the turbo vane servo motor was seized. I had managed to acquire a low miles unit from a similar engine and the car is now like a road rocket.
Simultaneously the servomotor for the egr appears to have seized and I got a complete one of those from the same motor as the above. They ain't flipping cheap. I thoroughly cleaned the egr and cooler.
I also changed the cam belt and bearings and the alternator belt and both its pulleys. I fitted new pads and linings at the rear also.
Youngest boy is chuffed, as am I if the truth be told, he couldn't believe it, cruising on the flat at 80 with the instantaneous fuel consumption at a steady 91 mpg, I couldn't believe it either.
This is the second volvo I've breathed new life into this year, the first for my eldest boy, a 200 quid mitsubishi v40 (02 reg iirc)from auction, spent 700 quid on it including a carsoft 906, new battery, cambelt and fan belt, new door handles, headlights, new discs and pads all round, arb bushes and rear drop links and it flew through it's mot.
The V70 was 2 grand more at auction and I've spent 400 quid on it.
TBH I think the v40 is the better car so much less to go wrong.
The downside is I'm nearly 80 and it knackers me to do these up especially as I've ripped my rotator cuff muscle in my right shoulder and I can't pull the spanners as I used to.
Now I have to do a service on the haldex unit on my TT and also change the rear dampers, never stops, does it.

[drone]

Son's put the better part of 1000 miles on it in the last week and it's still running sweetly.
I dismantled the old servomotor and, to my surprise, could get the actual motor to work with the application of 12 volts direct to the motor terminals.
The pcb doesn't small of cooked bakelite and there aren't any duff soldered joints as far as I can see, neither do any of the components appear burned.
Over the weekend I'll connect the old servo motor to the system electrically and see if I can wiggle it with vida.
For what it's worth, if the servo motors are seized, they are a pig to get out if the arm is in the wrong place, I had to cut away the plastic retainer to be able to get the damn thing out of the bracket.

[davebb]

Thanks for posting what you have found,
Does your son help you working on his car?
keep use updated,
Thanks Dave

[drone]

Originally Posted by davebb

Thanks for posting what you have found,
Does your son help you working on his car?
keep use updated,
Thanks Dave

Sorry to take so long to respond, yes he does help me, he stays indoors .
BTW car is still running great 13000 miles later.