New MVS Contributor ReWagner posts a great PDF that shows how to remove and replace the ABS pump in P2 Volvos…
For some time I have had an ABS message – with trouble codes BTM0070 (pump motor supply voltage, faulty signal) and BCH0072 (pump motor, mechanical error). The online information that I could find suggested that the likely problem was a faulty Brake Control Module.
At first the ABS message was intermittent, then continuous. I got a used BCM and replaced the old one. That solved the problem for a while, but it became intermittent again, then continuous.
I sent the original BCM to XeModEx and had it rebuilt, to repair the power leads and to put a more robust pump driver in it. That solved the problem for a while again, but the ABS message soon returned intermittently. I called XeModEx and they told me that often the pump motor is faulty, rather than the BCM.
So I bought a used ABS pump motor and replaced the old one. That has solved the problem.
I am posting because I could find no reliable information on how to replace the ABS pump motor itself, without taking the entire ABS pump assembly out of the vehicle. That would have required the brake lines to be removed from the ABS pump assembly, and when the ABS pump assembly is reinstalled the brake lines would need to be bled.
Instead, I found that it is possible to remove and replace the ABS pump motor without taking the ABS pump or the BCM out of the vehicle. That avoids the need to remove the brake lines from the ABS pump, so it is not necessary to bleed the brake lines after the repair.
I am including what I learned about how to make the ABS pump motor replacement in the attached document. There are some photos in the attachment that may help understand how to do it. Perhaps this information will be useful to someone with the same problem.
From the ABS Pump Replacement downloadable and printable PDF:
Here is how the pump works:
1. The motor shaft is offset by a small amount (1/16” or so)
2. The shaft sits in a bearing in the aluminum pump block
3. The bearing sits between two spring-loaded pump pins in the pump block
4. When the motor shaft turns, the bearing oscillates, pushing the pump pins
in and out alternately
5. The pump pins are sealed by o-rings, so that no brake fluid is leaks out to
the oscillating bearing or motor shaft
6. The motor is mounted to the pump block by two Torx screws
7. There is a seal on the motor that mates with the pump block surface
The pump motor has two brushes that are worn so it won’t operate properly. The
brushes can be replaced or the pump motor can be replaced with a used motor.
The parts and procedure is very likely similar or identical to these Volvos:
- 1999–2006 Volvo S80 (P23),
- 2001–2007 Volvo V70 (P26E),
- 2002–2007 Volvo XC70 (P26L),
- 2003–(current) Volvo XC90 (P28)