Hi, Australian delivered 2009 MY10 XC90 Executive with 3.2 petrol motor has recently started displaying "Anti-skid service required" on the dash display.
I have purchased an icarsoft CR Pro, the scanner is reporting a couple of codes:
C002201 Brake Booster Solenoid. General Failure Information. General electrical failure
and
C111802 Brake servo disengage switch. General malfunction Information. General signal error

I have replaced the Brake pedal position sensor but no change. I think the issue is the other sensor located on the brake booster, it's circled in the attached picture.
I can find very little information about this sensor on the internet though.

Using the CR Pro I think I can see the signal that is causing the problem. Using the live data mode, there is an input "Pedal pressure sensor status" that is either "not activated" or "started". If I clear the codes and then keep pressing the brake pedal lightly, after a few presses it will stay on "not activated" and the error code will be displayed on the dash. I can unplug the sensor I have circled, and the sensor data won't be displayed at all so I'm fairly sure that this sensor is broken, the ABS unit it is connected to is broken, or the wiring is broken.

My next step is going to be to remove, inspect, clean, and replace the ABS module

If I need to replace that circled sensor, can anyone advise whether I need to replace the entire booster? It appears to be installed in this booster:
https://www.fcpeuro.com/products/vol...er-xc90-300234

Thanks for any time you can put into this,

 

I've bought a new second hand ABS computer with matching numbers and installed it into the car. The CR Pro then complains about:
U030087
State: None
Control module incompatible internal software,
Bus/message Error, Message missing

I believe that to use this ABS computer, it needs to be updated with the vehicle's VIN. After discussing with a Volvo tech it is the CEM computer that is responsible for checking the ABS computer and then throwing the error.

Does anyone know if there is a code scanning computer that is able to do this update?

The original problem however is not fixed with the new ABS computer, the car still generates the ABS error when pressing the brake pedal.

I've checked the wiring between the booster sensor circled above and the ABS computer per the wiring diagram and it is all good.

If I probe between pin 1 and pin 5 on that sensor for continuity, I see an inconsistent output. It is just a switch between those pins, but it frequently fails to correctly trigger when the brake pedal is pressed, so when it does not match the numerous other sensors telling the ABS system that the brake pedal is pressed, it errors.

I've bought a new 2nd hand booster which I'll be installing in the next week or so, I hope. It's a RHD car and there is very little room between booster and engine.

 

I've had a go at installing the booster and what a headache, and not worked it out as I type this.
There's not enough room between the firewall and the engine. I unbolted the weird plastic chamber from the rear of the valve cover.
The heat shield can be removed with a bit of maneuvering after removing two 13mm nuts.
The master cylinder can be moved out of the way without opening the hydraulic system. There are another two 13mm nuts.
Inside the car put the seat back, remove the cover above the driver's knees with a torx screwdriver. Get the driver's door wide open and get on your side to wiggle up under the dash. Remove the clip on the rod connecting the brake pedal. A deep 13mm socket is needed to remove the 4 nuts securing the booster to the car, do not let them drop under the carpet.

Now here's the problem, the booster is completely free now, but it can't be moved far enough forward for the rod/plastic plunger thing to get out of the hole. It hits on the engine. This is a RHD car and this isn't a problem on LHD cars.

So because I've got a booster sensor failure that can't be replaced, now I'm trying to work out how to drop the entire engine! Just because of a sensor. That can't be replaced. It's a very crappy design Volvo

 

Please keep in mind I do not have a 90 sooooo.

May be worth trying to remove the upper engine mount or other mounts that prevent the engine from rocking back and forth to see if you can move the engine enough to remove the booster.

VERY important to remember that the upper engine mount (the one you can see in the last picture) holds the engine up. You will need to support the engine. Something under the engine with a wood block to spread the load to prevent damage. Oil pans and such can be weaker than you want to think.

 

Thanks for the reply!

I've been working on this all day again and I can't get it out. I've undone all 4 of the sub frame bolts and dropped the engine down about as far as it will go and there still is not enough clearance to remove the booster.

That upper mount does not support the weight of the engine in XC90, but now you've suggested it I might try removing it and see how far I can rock the engine forward.

 

Hey ssicarman,
Thanks for the suggestion to look at that upper engine mount. When I removed it, the engine/subframe would drop a heap more and I was able to remove the booster! The replacement booster is all fitted up, I've reassembled everything and after taking the car for a test drive the issue with "ABS Service Required" seems to have been resolved!

I've done a write up of the details involved with removal of a RHD booster here:
https://ozvolvo.org/discussion/14677...er-xc90#latest

Thanks