I searched my Service manual last night and couldn't find this in there. Sometime a long time ago there was a post that explained how to do this, but of course with the new software all the history is no more.

Does someone have the instructions on bleeding the ABS (the ABS/ASR box behind the driver's seat on the 92 and up cars)? If so, I would really appreciate getting them from you. I'm not sure if this is my problem, but it wouldn't hurt to do this as it hasn't been done in a number of years.

Thanks in advance,
Mike

 

The one thing the '92 has is a ABS "Prime Pipe" from the left hand side of the master cylinder reservoir that runs directly to the ABS unit behind the seat.
There is a bleeder valve on the side of the ABS unit to bleed this Prime Pipe. You can simply vacuum bleed it, making sure the reservoir does not run dry.
I'm not sure, but I don't think later LT1s have that.

Tom Piper

 

Thanks, Tom! I will attempt to do this over the weekend.

I no longer have the stock MC (using a Tahoe MC now), and am not using the stock reservoir either. My engine builder drilled a hole in the side of the reservoir, and inserted a hollow plastic tube into the reservoir and glued it in. He punched a number of holes into the tube that allow the fluid to drain back into the reservoir. The hose from the ABS unit fits over the tube and is clamped down with the same clamp as before. I hope this setup works as good as before.

My problem is I still feel as though I have air in the lines but nothing is coming out of my 4 calipers. I am hoping the problem is in the ABS prime line. This was never bled after putting in the new MC, and fabricating the lines going from the MC to the proportioning valve.

I hope this does it,

Mike

 

Our 94 manual has the bleeding procedure.

It's on page: 5-10 brakes with acceleration slip regulation (ASR).

So the 94 also has the 'prime pipe'.

The manual specifies bleeding the prime pipe (as Tom noted) but also suggests putting a short piece of clear tube over the bleed screw with the other end in a clear container (perhaps to keep the fluid off the metal surface to avoid corrosion).

I also had read somewhere that even after bleeding the ABS/ASR unit there could still be some air inside the valves/pump within.

It was suggested to take the car for a ride and hit the brakes to force the engagement of the internal valves and then doing another bleed at the brake cylinders in order (RR, LR, RF, LF).

 

I don't know what year they stopped using the prime pipe, but my I don't think my neighbors '96 has it.

Some ABS units can only be bled with a scan-tool that keeps the ABS valving open during the bleed process -- my Ford Ranger is one.


Tom Piper

 

I have vacuum bled that prime pipe on my 93... and I really did not notice that it achieved anythng. Actually, I have always understood that simply bleeding each caliper should be sufficient. Somehow the ABS is (either upstream or downstream, depending on how you look at it) from the calipers and should not be affected. FWIW... I just go out and cycle my ABS through a series of "fun" starts and stops and then rebleed the brakes... probably not very orthodaox, but my car still stops!

 

If the ABS unit is new or had been removed from the car, the service manual says you need a Tech-1 Diagnostic Tool with the brake module installed to properly bleed the ABS.

The Tech-1 and brake module will allow the ABS pump to run so fluid will pass thru it as the brakes are bled. I would assume that the bleeding would be done by a pressure bleeder so that fluid can be pushed through the master cyinder reservoir out to the calipers as the pump runs.

The first time I prepped my 92 for a track day, I was running out of time and I took the car to my dealer to have the brake fluid flushed and refilled ( I took 4 cans of Ford Motorcraft HD fluid with me and you should have seen the look on the service writer's face )

When I told them that I wanted the ABS pump to be flushed and bled, they brought out their brake systems tech and he told me that that step was not really necessary and they even don't reccomend that procedure if nothing is wrong with the ABS pump itself.

The ABS pump does a "self-test" at every start-up (that's the buzz you hear at about 2-4MPH) and it is actually moving some fluid between the ABS and the M/C. Eventually the self-test will pass the fluid from the ABS back to the M/C reservoir. Just before the track day, I simply sucked the fluid out of the reservoir and replaced it with new fluid.