[T-Cut]

With almost all cars now fitted with ABS, does this mean any DIY brake fluid maintenance on them is ill advised? Are the brake fluid replacement instructions given in the Haynes Manual incorrect?

EDIT: The other manual (that dare not speak its name) describes brake bleeding exactly like Haynes does. Even when the ABS modulator unit has been removed and refitted, the procedure for fluid bleeding then links directly back to the earlier description using rubber tubing and a jam jar. The only reference to T4 in this section is to clear fault codes. The hydraulic flow diagram shows that there are several 'loops' within the ABS unit which are opened/closed by solenoid valves according to instructions from the ECU. However, all are connected directly to the master cylinder via the primary and secondary circuit pipes. Adding fresh fluid to the master reservoir will allow the pedal to pump it through the ABS modulator, but only those connections which are normally open. In other words, the loops which are opened during ABS activation will not receive the fresh fluid during the bleed. Having read through the manual, I can only conclude that these loops need not be bled (using a T4 to open them) unless the hydraulic fluid has more or less drained away leaving the ABS unit full of air. This could obviously get into the loops if the brakes were applied under conditions that would activate the ABS system. However, the details on refitting an ABS unit makes no such reference. I wonder therefore, what the routine is for fitting a brand new, 'dry' ABS unit? I would have expected that to be covered in the brakes maintenace section, but I can't see it.

TC