OBDII ABS Brake Bleeding With Jumper Link - Corolla E11 2001

[Gerg]

Hi, I understand that the ABS pump on a Corolla E11 (2001 - Burnaston built) can be forced to operate via shorting out a couple of pins on the OBD2 port, so as to achieve a thorough brake bleeding.

Does anyone know which pins you jumper?

 

Thanks in advance.

[oldcodger]

Hi,

Wonder why conventional brake bleeding is not working for you ? 

If you want one man bleeding there are plenty of devices to achieve good results - have used the Gunson one for many years.

Feel sure the forum  would have heard about using the abs pump to bleed the brakes before now if it was practicable..  though not saying it isn't possible ..?

Who's suggesting it is ?

[Gerg]

Thanks for the reply,

This is an ongoing problem of poor pedal 'feel'. I have an idea that the problem started when air was allowed into the system during a previous bleed a long time ago. 

The jumper 'technique' was only recently mentioned by a technician at a Toyota main agent.

They had the car in to bleed the brakes (for the above problem), but when it came back it was actually slightly worse.

Since the garage bled the brakes, I have used (all at the same time, just to get as much flow as possible) a Gunsons easy bleed, a suction pump, and pumping-the-pedal. In the past I have tried all these methods independently, but with no improvement.

The brakes are now back to how they were before the garage bled them, but still not as they should be.

FWIW, with the handbrake on hard, the pedal travel is exactly the same.  To an extent, if the brake pedal is really rapidly pressed then the pedal becomes a bit better.

The car passes an MOT with no problems, and is running genuine Toyota front pads and original rear brake shoes.

[oldcodger]

Hi,

Well think you can feel reasonably reassured if it passes the mot, I believe they deliberately  use the brakes fiercely to try and show up any fault.

Similary if you have had a Toyota mechanic check the brakes it should be good ...?

Have used the same Gunson bleeder for 25 years on 4 cars and never had a problem with it.

Things I would be checking on, front disc thickness, rear drum internal diameter, are they below spec;   brake flexible pipes might be bellowing slightly giving you that spongy feeling; I changed mine after 10 year as a matter of course , though they were looking rather rusty around the ferrules.

Assume if you have new pads you have done a few  hundred miles on them as they can take time to bed in and can feel odd until they have bedded in and am sure  that you are using fresh dot 4 fluid of a good make.

Getting complicated, you could have a slight problem with the brake master cylinder or servo, but again would have thought the Toyota mech  would have noticed that ..?

[DeTomato]

Are you using DOT 3 or DOT 4? In my car its DOT 3 and the brakes have been done and feel the same as before, even with new pads in the back. The brake pedal is naturally spongy I've seen from my prior car of a different manufacturer. But pumping brakes when it's standing without the engine running will tend to make the brake pedal come up and feel firm because the system is the under pressure. Turning the engine off will release that pressure underfoot. Is this what you're seeing?

[Gerg]

Thanks for the ideas.

Eventually, at the suggestion of an independant garage, I tried bleeding the brakes exactly as before, but with the engine running (!). He was putting the point that the ABS pump would be in an different state when 'armed'.

This seems to have made a marked improvement; the brakes are almost normal now. 

Ages spent googling failed to show up the 'OBD jumper trick' that a Toyota technician mentioned could be used to actuate the ABS pump.

[roks]

When you do pressure bleeding, does the fluid flush through the abs? I  was under the impression it didnt. Some suggest that after bleeding you should do a few hard brake to activate abs and then bleed again....never had the patience to try that. 

[Gerg]

I agree, I don't think bleeding does properly flush the ABS unit unless you can operate it via a diagnostic mode, or on older cars, a jumper on the OBD port (?), some say.

Techstream (TIS), and I imagine, other diagnostic tools don't seem to be able to operate the pump during a bleed. This car (2001) is too old for them to be compatible. But I'd love for someone to correct me on this.

I have tried attempting to lock up the all the wheels, making sure that each had had some ABS operation, no easy job, especially as the rears don't do that much anyway. A subsequent bleed didn't make any difference for me.

Amazingly, a brake bleed at a Toyota main agent made this 'excessive pedal' problem worse. I can't figure that out!