Brake module failure

[Simpo Two]

Two warning lights have been on for a couple of months - 'Traction control system off' and 'DSC service required'. Today I got them looked at by a recommended indy during a routine service. We'd hoped they might be caused by a poor battery, but it was tested and is fine. He says this means the brake module could be faulty or have a loose connection, and that it could be difficult to investigate/solve. Can anyone throw any light on the subject please? 2007 DB9, 30K miles.

[DB9S Paul]

I assume he read the codes, that should give more information, could be just a speed sensor.

[Simpo Two]

DB9S Paul said:

I assume he read the codes, that should give more information, could be just a speed sensor.

He had an Autel code reader but not AMDS.

[LTP]

Just semi-educated guessing here, so don't let me raise your hopes, but if you don't have an ABS warning as well that to me implies the ABS system is working OK, which requires the brake module to function correctly. Similarly the ABS system requires the speed sensors of all four wheels to function, otherwise it can't detect a locking wheel. There are quite a few other bits like pumps, pressure sensors and the yaw sensor in the system required to make the DSC and traction work.

A good tech with AMDS should be able to see which component is registering DTCs, so it may not be the main module. It's possible an Autel won't give the full suite of codes, so I think I'd take it to someone with the right diagnostic kit before you let your indy start playing "swap the parts".

[Simpo Two]

In case it's any help to fellow owners, I got it seen to elsewhere, and this is the somewhat abbreviated story copied from the invoice:

'Investigate traction/ABS issue. Carry out code read faults relating to brake pressure correlation. Analyse live data found. Line pressure reading 198 bar without any pedal pressure applied. Gain access to sensor. Carry out wiring checks OK. Emulate signal to module OK. Fault clears OK. Require new brake pressure sensor/bleed brakes. Install new sensor, bleed brakes, calibrate brake pressure sensor. Test OK.'

Fixed for £561 inc new brake pressure transducer and VAT. Not bad for an Aston I thought.

He also found the battery was a bit ropey and was AGM not EFB, which a 2007 DB9 should have, apparently. He fitted he correct one (not included in the £561).

Edited by Simpo Two on Friday 8th August 11:21

[LTP]

Glad you got it fixed and it wasn't the £££'s that a main brake module would probably have been.

It's interesting (at least to me) that the guys that fixed it seemed to have far better access and analysis capabilities than your original Indy and his Autel. Did they have and use AMDS?

[Simpo Two]

LTP said:

It's interesting (at least to me) that the guys that fixed it seemed to have far better access and analysis capabilities than your original Indy and his Autel. Did they have and use AMDS?

No, the remarkable thing is they don't have AMDS. The boss is, however, a minor genius at diagnostics and has a lot of other kit. (He was the one who diagnosed the earlier torque converter problem, whilst Stratton with AMDS and '75 years experience' couldn't get any codes and said it was a misfire)

The first bloke specialises more in pre-Gaydon Astons and I think simply isn't up to speed with later developments.