Bleeding ABS without computer tool

[WondrousBread]

A few days ago I posted about my clutch troubles. Following that, I replaced the slave cylinder which did not fix the issue. Next step is the master, then if the hydraulics are eliminated as a possibility it's on to mechanical.

My clutch master cylinder (2004 Toyota Celica GT) is sandwiched between the brake master cylinder & booster, the firewall, the inner fender, the wheel well below, the wiper cowl above, and the shock tower. The only way for me to remove it is to take out the brake master cylinder and booster for access.

Since I have ABS and don't have a tool that supports cycling the system for bleeding, has anyone done it without the tool? And if so, how? Since the master will be removed and replaced, I'm definitely going to trap some air in the ABS.

Thanks, Chris

 

[Dave9]

The general procedure is find some sand, gravel, ice, or snow, and drive around locking all the wheels up to activate ABS to purge air out, then bleed the brakes, then repeat till normal ABS function is observed and no sponginess.

It is not foolproof or guaranteed, if there is still a problem then take it to a shop with the tool.

 

[cjolson140]

I just replaced the brake master on a 1999 mk4 VW Jetta TDI, and I was nervous about this situation as my VCDS scan tool doesn't work.

The old master cylinder failed in such a way that I couldn't get brake fluid to appear at the front right wheel, and that caliper couldn't retract until I disconnected the rubber line from the hardline. It seemed like that hardline (and presumably ABS circuit) were full of air at this point. Brake pedal stayed on floor 50% of the time while trying to bleed.

Before I installed the new master, I filled it with its brake line ports blocked (little red plastic caps that it came with) before I put it on the car. I didn't bench bleed it. After installing it & connecting the brake lines from the ABS block, I filled the reservoir and proceeded to re-loosen the brake line fittings at the master until I could see air bubbles coming out past the threads. Then I let it sit for a while before tightening, until the fittings were wet with brake fluid.

After this I was able to bleed the problem wheel with no issue, and the brake pedal feels hard and brakes evenly on all wheels. Maybe I just got lucky but I didn't need to cycle the ABS. I have a missing wheel speed sensor as well, so the ABS hasn't cycled at all since this repair; maybe I'll get a soft pedal and need to bleed some more after fixing the ABS and cycling it?

 

[ET16]

See, too, what the recommended sequence is for your cart.

 

[Gasbuggy]

Some ABS systems trap air, others don't. When you turn your key on and off, the ABS should cycle. I had a system majorly full of air on my old CTS-V, a notoriously hard ABS system to clear (even dealerships have trouble). I hooked a Motive Bleeder up, pressurized it, and cycled my key on and off about 30 times.

 

[ARCOgraphite]

I'm up against this right now, my wife's brakes on the Subaru are mushy and the pedal is low. I traditionally bled the rear brakes to no avail.

Online I saw something about a 6 position harness under the dash where if you short two terminals together it will cycle the ABS
( after some key-on and pedal pushing hacks) This is an open connector like an ALDL port and it has two free grounding pins tied to the cable just behind the connector.

Now If I can get under the dash without dislocating something in my creaky upper body.

I don't really want to go to the dealer, they messed it up in the first place with the 30K brake system fluid "exchange"

 

[mk378]

Check the service manual to see if disconnecting the brake master is really required for this job. Don't do it just because you think you have to.

 

[Saabist]

It probably varies on different ABS systems. I get good results using a Motive pressure bleeder without going through any special procedures.

 

[JDJ]

Are you sure you can't just unbolt the brake master from other components to free up some space, without breaking the lines free?

On my old 94 Grand Marquis, I was up against this very same question. I was able to finally get all air out of the ABS system when I used a hand operated mighty-vac and suctioned the fluid out from the rear lines, then the front. Doing that was the answer I needed... since I could not cycle the abs at all, even if I slammed on the brakes on ice. There was that little of braking pressure. Shouldn't have been driving it like that.... but alas...

 

[nthach]

On Toyotas, you can bleed as normal. You will need Techstream or the equivalent for the hybrids and maybe the Land Cruiser/LX, 4Runner/GX, and the 2nd generation Lexus GS.

 

[WondrousBread]

So as a quick update, it wasn't nearly as bad as I'd thought.

I did have to remove the brake master cylinder entirely to get enough clearance to get to the clutch master, but conveniently I didn't need to remove the booster (although it was a tight fit). Since the two lines leaving the brake master go outwards and then make a 90 degree downward turn, It wasn't possible for fluid to drain out other than a few drips. Consequently, air couldn't really get in as long as all points lower than the master cylinder remained sealed.

Once I had replaced the clutch master cylinder, I put the brake master back in (being careful not to drain more fluid than I already had). When I connected the flare fittings I only engaged one or two threads, then connected the mounting bolts up and filled the reservoir with fresh fluid.

Then I let it gravity bleed. I could see and hear bubbling from the fitting, but once the bubbling stopped, a slow but constant stream came from the fittings. Tightened them down, pumped the brakes a couple times, and it now feels perfectly normal. I will definitely bleed properly in the coming days, but any amount of air in the system is certainly minimal (pedal feel is unchanged).

On the downside, my clutch still doesn't disengage even with all new and adjusted hydraulics. So that means tomorrow is transmission removal day.

Thank you everyone for the advice, I appreciate it