ABS on 90's Imperials

[Brad Hogg <roadhogg@xxxxxxx>]

First I talked to Chrysler USA and I was told that the pump and piston
assembly was under lifetime warranty but PARTS ONLY.  When I talked to
Chrysler Canada, they told me that they were covered for parts AND labour!
This is a lifetime warranty.  They each asked the mileage of the car and I
told them 320,000 km.

Unfortunately for me, according to my troubleshooting, I don't think it is
the pump.  I think it is the pressure switch that tells the pump when to run
because if I bypass the switch and run the pump manually, I get all the
power boost I need.  The trick is in fooling the computer into allowing the
system to pass the initial test phase so the warning lamp goes out.  I've
discovered how to do that too.

In this diagram...
http://imperial.point2this.com/misc/CarStuff/ABS/ABS.jpg
you can see the DFPS (dual function pressure switch).  This is the component
that I suspect to be faulty.

In this diagram...
http://imperial.point2this.com/misc/CarStuff/ABS/Schematic.jpg
on the lower right corner of the schematic, you can see the DFPS (part
#04485632) and that it will connect one either of two circuits to ground
depending on the system pressure.  The lower switch in the unit will be
responsible for grounding the pump when the accumulator pressure goes low.
I've tested this switch and even when there is no boost in the system,
indicating there is no accumulator pressure, the switch does not ground.
When I ground pin 1, coming off that switch, the pump runs and brings up the
accumulator pressure and provides boost.

The biggest problem now is replacing that switch as it is nearly
inaccessable on the bottom of the accumulator assembly near the firewall.
My dealer wants $174.00 CDN for that switch so replacing it may be the
second hardest part of this repair.  They'll replace it for $79.00 labour.

I'll do more diagnostics when I return from Rhody Days in Oregon...I LEAVE
TONIGHT!!!!  WOOHOO!!

----- Original Message ----- 
From: "Philip Brust" <pbrust@xxxxxxxxxxxxxxxxxx>
To: <roadhogg@xxxxxxx>
Sent: Tuesday, May 18, 2004 10:24 AM
Subject: ABS on 90's Imperials


> Brad-
>
> Check the www.allpar.com website. When I was bending over to fix my Bosch
> ABS ($1100) I noticed they had quite a bit of info on the extended
warranty
> for the Bendix system. If I recall, you're beyond warranty but maybe they
> had a different program in Canada. Be thankful you don't have a Bosch
> system.
>
> Phil Brust
> 73 & 82 Imperial
> (Past owner of 90)
> Jefferson GA
>