2006 XC90 BCM Diagnostic Codes

Post by **cuhfs** » 16 Oct 2025, 14:48

Not sure where to start to resolve these codes.
ABS warning light and Brake assist warning lights are lit on dashboard

OBDII CODES Read AS FOLLOWS:
BCM-C00201C ABS PUMP MOTOR CONTROL
BCM-C004664 BRAKE PRESSURE SENSOR "A/B" Signal Plausibility Failure
BCM-U042864 INVALID DATA RECEIVED FROM STEERING ANGLE SENSOR MODULE Signal Plausibility Failure
BCM-C004401 BRAKE PRESSURE SENSOR "A" General Electric failure

Replacing the Brake Pedal Position Sensor (on the brake booster) did not help.

1.) Should the next step be to replace the Brake Pressure Sensor on the Master Cylinder?
Or 2.) the Steering Angle Sensor? Or... the actual BRAKE CONTROL MODULE? Or the ABS Pump?

What are the best next steps versus my just throwing the parts at the car and guessing.?

Thanks for any advise!

dikidera · Post by **dikidera** » 17 Oct 2025, 01:34

In my humble opinion, and I'd like to point out I've never had to diagnose an ABS, if the module is reporting an issue with the motor, then it does seem more likely the ABS is either dead or on its way out.

Of course since I've never dealt with this issue, I do not want to mislead you.

Capndirk · Post by **Capndirk** » 17 Oct 2025, 09:44

I had a fault with the motor on my '09 BCM that caused an anti-skid message. VIDA read it as a "vacuum motor" fault. After a lot of research, I found a thread in here about the brushes in the BCM motor. I only had around 90k miles on it, at the time. I harvested a motor that looked similar from a random Volvo in the junkyard that was easier to access and installed it in mine. I had opened another motor at the yard as well as the "new" one, and the brushes were fine. I opened my take-out, and the brushes were gone and it was a carbon dust mess in there. Problem solved for 50k miles since.

Post by **abscate** » 21 Oct 2025, 01:46

I it is a similar BCM to the P2 line it’s only 4 E4 or E5 torx to drop the module. Drop it , undo the electrical connector, and then send it to Xmodex for a work over. Unlikely to be the motor.

Try clearing all codes and see what comes back, first, though

Post by **ggleavitt** » 21 Oct 2025, 12:07

This post might be helpful, another V8 Ocean Race with a BCM issue- https://www.swedespeed.com/threads/bcm- ... or.645377/
Resolved for the time being with both pressure sensors replaced ('05 V8 donor) but I remain convinced that it's a BCM issue. Have a good read of the thread as the error changed over time. Zero problems with my '08, just the Ocean Race ('06). I'll be interested if the module gets sent back for rework.

Post by **cuhfs** » 22 Oct 2025, 20:42

Guess i Will try pressure sensors since they (aftermarket ones) are cheap abd easy. Will do bcm if problem remains

Post by **ggleavitt** » 24 Oct 2025, 11:00

Think I had written yesterday but forgot to send. Might get your VIDA/DICE out and look at live parameters for the pressure sensors. Key to my problem was the gross difference between the sensors and the choppiness of the signal for the differing sensor. It's one of the photos in the thread. Sometimes a DSTC calibration would work, when it did the sensors were reading within a few bar (calibration does the offset so they match in the BCM) and the error would clear. I would go for a drive, all good for a bit then the error re-appeared and the live readings noted a gross delta (15-20 bar) again. This was my issue, resolved as best I can tell by the sensor replacement (did both) but as the error moved on it's own over the years from one sensor to the other (B in 2021, A in 2025) , I'm not thinking sensors is the common factor. As of my writing, it's been been a couple months since the replacement and no errors. Maybe it's resolved. Maybe.

Post by **cuhfs** » 24 Oct 2025, 11:34

ggleavitt. Understood.

Post by **cuhfs** » 24 Oct 2025, 21:34

ggleavitt, did you use aftermarket or bluebox?. Huge price difference .

Post by **ggleavitt** » 26 Oct 2025, 09:17

I put in ProParts but think I may have only done one sensor and it made no difference (calibrated okay but then went wonky).
In the end I replaced both sensors from a master cylinder that I pulled from a '05 XC90 at a local PicknPull to avoid confusion. If you have somehwere you can grab a whole master cyllinder, pretty much all P2s (S60/80, XC70/90, V70 example) use the same parts. Two small pipes to detach and a couple nuts on the firewall, master cylinder pops right out.