Audi nearside brake imbalance... NCT Failure

KK4SAM

Help required,Audi A3/03 failed on rear brake imbalance.I have replaced the caliper on that side and the imbalance remains.Using VAG diagnostics its evident that the ABS unit is not communicating with the ECU.The question is,is it possible for the ABS module to fail in such a way the its preventing pressure been applied to the rear nearside brake.The handbrake has 1% imbalance ruling out,Disks & Pads issues.A new replacement ABS unit is cost prohibitive for the age of the car.
Is it feasible to install an ECU and matched ABS module from an identical car what other issues am I likely to encounter ? Any advice greatly appreciated !

[IMG][/img]

porsche boy

Is there an ABS light on the dash?

Are you sure the caliper was the fault? It can be possible for the solenoid to stick in the ABS pump but it would be a case that the solenoid would stick and not pulse when the ABS kicked in.

When you changed the caliper are you sure you purged all the air from the system?

I have seen inner degradation of rubber hoses restrict brake fluid flow causing imbalances, what condition is the brake hose in?

KK4SAM

Thanks porche boy for your response.There is an ABS light on the dash but I was putting this down too the non communication.
I first suspected a bulging flexible hose but they are in good order.I don't suspect a restriction in the flexi as it almost bleeds by gravity and not shortage of fluid when pressurized.

rex-x

KK4SAM wrote: »

Thanks porche boy for your response.There is an ABS light on the dash but I was putting this down too the non communication.
I first suspected a bulging flexible hose but they are in good order.I don't suspect a restriction in the flexi as it almost bleeds by gravity and not shortage of fluid when pressurized.

The abs light is a fail anyway so maybe it would be wise to start with that and go from there? New module will need coding unless you happen upon one with identical coding already (same make model and year can still have different coding)

KK4SAM

rex-x wrote: »

The abs light is a fail anyway so maybe it would be wise to start with that and go from there? New module will need coding unless you happen upon one with identical coding already (same make model and year can still have different coding)

I don't think the light been on is a failure ,but if the fault indicator lamp is failed it will fail the NCT :
"The NCT also checks that the Malfunction Indicators are in working order. You car will fail this part of the NCT if the following dash lights are not working or if an obvious modification affects correct operation:

Supplemental Restraint Systems
Airbags
Electronic Stability Control
Anti-Lock Braking System
Electronic Braking System
Parking Brake
Tyre Pressure Monitoring System
Electronic Power Steering
Brake fluid warning light"

rex-x

It is 100% a fail:

anti-lock Brake System
REASONS FOR FAILURE
(4) Warning light not working or indicates a defect in the
anti-lock system.