BCM-0130 ABS Trouble shooting question

tsandrews02 · Post by **tsandrews02** » 24 Jan 2022, 19:14

I'm currently trying to bring back to life a 2006 Volvo XC90 that has spent the past 4 years sitting outside without being cranked. Got everything running. Basically, replacing most everything rubber like hoses and belts due to dry rot. Even had to go through the fun of getting to the fuel pump so I could pump out about 10 gallons of 4 year old gas.

When I powered it up and and cranked it, I got a BCM-0130 error. From some reading I have been doing the ABS control module it self could be the issue. However, I want to verify that the sensor #1 itself is not the issue first before replacing the ABS control module since you are looking at a $45 part versus several hundred. I do know that this error was not there prior to the vehicle sitting for a while so I'm trying to look first at things that could relate to sitting first. I did replace all the vacuum hoses for the brake boost already to rule out leaky hoses. I was looking at trying to probe the signal line on the sensor to see what the readings were but i don't have a good reference to know what it should be so I would only be able to detect if the sensor was totally intermittent versus reading a bad voltage. One thought I had was to look at the signal level coming off of sensor two as a reference to see if they were similar or maybe just switching the sensors to see if the problem moves with the sensor or stays stationary.

Does anyone know if the pressures are similar enough that you can use sensor one and sensor two to compare? My guess would be that if I am getting similar signals from each sensor that it should be an indicator that I have an issue with the control module.

Suggestions?

Post by **RickHaleParker** » 24 Jan 2022, 20:54

Faulty signal. Most likely due to moisture getting into a electrical connector. No chance to dry out because of no heat coming off the engine for four years. Clean the electrical connector to the brake pressure sensor and the BCM. Then clear the codes.

tsandrews02 · Post by **tsandrews02** » 04 Feb 2022, 21:05

Thanks for the tip on cleaning the connectors. I actually over looked that. I went ahead and cleaned the connectors at the sensor but wanted to log some data before tearing everything apart to get to the other ones. Before connecting the sensors back up I used a multi meter to verify I at least was getting my 5 volt supply and had good ground. This left only the sensor output which I will check the continuity when I remove everything to get to the other connector. I used my scan tool to get the readings coming off of each sensor. Without pressing the brake, Sensor 1, the one more front, was giving a reading of 23.5 bar, while sensor 2, the one behind it, was giving a reading of about -1.1. So I set up a little table to help trouble shoot. I systematically disconnected and reconnected the wires and took measurements every time. I then switched the wires to where sensor 1(the front one) was sending to sensor 2 output on the scan tool and vice versa. In order to keep myself from getting confused, I named the output "Reading" so I would keep it straight that i was looking at what was being displayed and not the actual sensor 1 or sensor 2.

: sensor matrix.png (10.88 KiB) Viewed 2845 times

In looking at the data, it looks like the readings stayed with the physical sensor. This is hopeful. Had the reading stayed with the wire regardless of which sensor it was connected to, I would be willing to bet money the problem was in the wires or the control. I am thinking that one of my sensors is bad. Does my conclusion look reasonable or am I missing something?

Tomorrow, I'm still going to disconnect the connector on the control module and clean out the connector just to make sure. After that I will likely go ahead and order new sensors. I personally don't like just swapping parts until things work. Not just because of the cost but I always have that lingering question of did I actually fix what was causing the problem. Let's face it, brakes are something I don't want to have those type of lingering questions.

tsandrews02 · Post by **tsandrews02** » 13 Feb 2022, 15:17

I wanted to give an update in case anyone else is running into a similar situation. I went ahead and purchased two new sensors. The sensors were only about $40-$50. With the way my luck runs it wouldn't be long before the other one went out too, The code cleared and the two sensors are only showing a difference of about 2 bar with and without the brake being pressed. I still want to get out on the road and test it out a little more but there are a few more things I need to get taken care of first since the car was sitting so long. Once I do get out and test drive it a little, I'll post an update. One interesting note I did noticed while trying to troubleshoot is that when I tried to calibrate the old sensors just to see if that was contributing to the problem, it gave me an error saying it could not detect the sensors. Now when I tried again with the new ones, it detected them just fine.

kingo · Post by **kingo** » 14 Aug 2022, 23:37

Hi - is it still working? I am having same issue - but it only happens when the weather is warm. I am seeing 3.97 bar on sensor 1 and -0.27 bar on sensor 2 - which seems far away from your measurements on sensor 1. Have you by any chance measured what the bar is with the new sensors?

And - when you swap the sensors - will the brake fluid run out (if you don't drain the container first)