Abs/brake Problem

[Ronnie Rav]

Hi, I have a 2002 d4d rav4. I took my car to a friend to fix because i thought the front drivers side brake caliper had seized up. On investigation it seems there is nothing wrong with the caliper, but the piston will not go back. when undoing the brake pipe on top the abs unit the piston returns ok but once done up it returns to being solid. All the other wheels are ok. My mate thinks its probably a valve jammed inside this unit but knows nothing about them. Has anyone come across this problem before? can it be fixed or will i need a new abs pump? Any advice much appriciated, thanks.

[jedi134]

Is it worth disconecting the Battery for a while, just to see if it resets anything?

[IanXT4]

Does your ABS warning light illuminate then go out when you power up the ignition ?

[anchorman]

I've never come accross this but it does sound like it is pressurising from the ABS pump. Have you tried jabbing the pedal to see if it un-sticks the pump? It might just cause enough back pressure to free it.

This why on modern motors, it is essential to change the brake fluid every 2 years. I looked at a Ford Fusion the other day and it had what looked like muddy river water in the res. The brake fluid can also collect moisture which could cause very finely machined parts to corrode and stick.

[IanXT4]

I have known very gentle tapping with a hammer to help loosen stuck solenoids. Obviously a large tap/thump will mandate a new ABS unit, so the emphasis is on gentle. If this works I would change the fluid immediately.

However, be aware that there is a possibility this "jam" could re-occur whilst driving causing a potential accident so you might want to get the unit thoroughly tested. To do this I believe you need access to Toyota's diagnostic tool to properly drive/test the ABS unit.

(Should the ABS unit be found faulty, breakers often have good used ABS units and there are also companies that specialise in rebuilding them. )

Any advice given is meant to be helpful and in good spirit. No liability is accepted for loss , damage or injury. WORK SAFELY

[Jamesbelfast]

I have seen similar symptoms due to a sticking caliper. In other words if the caliper won't retract the valve inside the ABS distribution unit fails to allow fluid to return. If the both front caliper plumbing connections are the same try interchanging the front calipers and see if the fault moves to the other side. Obviouisly you will need to fit suitable packing pieces as the calipers won't physically fit. No gaurantee that's your problem but it may prove exactly where the fault lies. Also caliper replacement would be much cheaper.