V70 - Brake Failure and Loads of Codes!

[Crawf]

Hi,

I have a brake failure warning light on the dashboard of my 2001 V70 (2.4). I had the OBD codes read at the local garage, and was amazed at just how many there were. I am a bit lost as to where to start in researching all of them. I therefore thought I’d try my luck see if anyone here can spot whether one or other of them is the root cause. Here comes the list……..

0095 Communication between control modules, Communication problems with active on demand couplings

0070 Power supply pump motor, faulty signal

1A5F Communication with the ABS control module. Signal Missing

A02B Communication, Control module for antilock brakes (ABS) faulty signal

0092 Yaw rate sensor, faulty signal

As an aside, is the following code as alarming as it sounds?

1A61 Communication with gearbox control module (TCM). Signal missing.

Appreciate that this is a lot to ask, but any advice very gratefully received!

Crawf

[davebb]

Hi
clear all the codes, charge the battery fully , low battery can do this,
re-test , then drive the car after some miles re-test,
Dave

[Georgeandkira]

Dave's advice is sound.

My guess from afar is that you have the common "early P2 bad solder joints in the ABS Module syndrome".

If it's that you can remove the ETORX#5 bolts from the bottom of the unit. You can send it off for resoldering (reflowing) or do it yourself. ETORX are external Torx. The tool is a socket where the regular Torx is male.

The good news is that you can still drive the car. It just wont have ABS.

[Crawf]

Hi,

The battery is new, and the codes have been reset and keep reappearing. So, it sounds more like it must be the P2 bad solder joints.

Will investigate.

Thanks for the pointer

[petey]

A new battery suggests it used to have an old one. The codes will be retained during a battery change so here’s definitely mileage in deleting codes when a flat battery has been present.

The ABS module can have dry joints on the main board. I’ve no idea if mine was similarly affected, but I cut through the plastic and got it out then touched each of the joints with a soldering iron to ensure good contact. This worked but only for about 14 months or so. The root problem was actually the brushes in the motor were desperately worn. Retouching the solder joints worked to reduce the voltage drop across the pump but it didn’t actually solve the root problem.

(Volvo use the same ATE pump and module design as all BMWs, Rolls Royce, VAG group, Mazda and many, many others. However, volvo specified a single bearing and a plain bush on the rotor for the pump when vehicles made at a similar time were using two roller bearings; as a result, the volvo rotor resonates and this causes premature wear on the brushes. I happened to have a Touareg pump in my hands and swapped out the rotor and magnet pack having first replaced the bearings and brushes. Worked a treat and it’s fairly simple to prove it is or is not the brushes. Don’t launch into it without researching exactly what’s involved though, there are some small parts which can make your day difficult if you wear varifocals....)