Brake Problem '96 Concorde 3.3 - Possibly ABS?

'96 Concorde LXI 3.3 no traction control, 132K miles

When I step on the brake pedal, car starts to slow okay. Then the pedal
begins to "chatter" (it's tough to describe what it exactly sounds and
feels like) and it feels like the braking system is failing. If I push
the pedal even harder, it stops chattering and the braking system brings
the car to a stop.

Had a mechanic drive it and he thinks it may be the ABS motor pulsing
and causing a chattering in the brake pedal. He said that he could hook
up their diagnostic system to check the codes but he wasn't sure how
much information you can get from the ABS computer for a 1996.

Occasionally, the ABS light will go on which I understand means the ABS
system is not working. When that happens, I have no problem with the
brake pedal chattering. Everything appears to work fine except I don't
get the advantage of the ABS.

Questions:

1. Will I get any useful information from reading ABS computer/controller?

2. How much of a difference will there be information obtained from the
computer if the measurment is taken with the ABS light on versus the ABS
light being off? The problem here is if the ABS light comes on and I
take it to the mechanic, he will say I have to leave it. When he gets to
it and starts the car up, the ABS light will be off.

3. Any guess as to what part of the ABS might be causing this?

 

Easy way to tell- pull the ABS master fuse and see if the car stops
normally. If it does, its the ABS. Me? I'd just leave the d*mn fuse out.
The braking system in the first-gen LH cars reverts to a conventional
system (with proportioning valves and everything) if the ABS is shut down.

 

i agree take the fuse out...but it dose sound like the abs pump also you
want to check the rear brakes and it usually don't do it when you leave
it some where to get checked that's the way it gose...

good luck......

 

That's exactly what I would do too.

The way it works, the pump is only caused to come on for one reason - A low
pedal. If it's coming on when the pedal is higher, then the switch that
regulates that must be screwed up. The pump doesn't really come on when the
system is actively working. It comes on when the pedal drops low as a
result of the ABS system dumping fluid off.