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Does anyone know if LHS's with ABS have softer brake pedals then non-ABS models? I added ABS to my son's car for better safety and the pedal has >0.5" of dead play and is scary mushy. Three trips to the brake shop for ABS bleeding and no improvements. The second shop thought the ABS module that I added was bad, so I replaced it. No better. They believe the pedal feel is "normal," for a car with first gen ABS, but admit it is not as good as most would want. I am wondering if it is the master. Thank you for any feedback.
 

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ABS will not affect the feel of the pedal, unless its operating.
 

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ABS will not affect the feel of the pedal, unless its operating.
But if air is trapped in the ABS system between the ABS valves, it will give a spongy pedal - at least on 2nd gen - I assume the same in 1st gen. The ABS valves have to be operated during a bleed cycle to get the air out.
 

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Something that might work (it did for me once):
Get on a gravel or snowy/icy road and hit the brakes hard enough to activate the ABS. That will force fresh fluid thru the ABS loop - and possibly dislodge any trapped air.

I had spongy brakes one time - kept bleeding, kept bleeding, still spongy. With them still spongy, on the way to work one morning at 55 mph, I was late seeing a school bus stopped dead in the road in front of me, and I had to light up the ABS. Suddenly, right after that: Brake pedal was nice and firm.

(Careful if you hit the brakes hard enough to try to lock them up on dry pavement - if your brake lines are heavily corroded/pitted, one could rupture.)
 

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Discussion Starter #7
Thank you for the suggestions. Funny thing, I did that and made a mess of the car with dust :) but still spongy brake pedal. Maybe I should try some more.

I hope you didn't hit the school bus. :eek:

Funny that you mention the corroded brake lines. These brakes lines were terribly rusted on this car as it in MI for 5 years, where they salt the heck out of the roads in the winter. We and they Intrepid are in AZ now. The cars in AZ junkyards here have pristine metal parts. So, I installed all "new" brake lines when I added ABS.
 

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I did not hit the school bus, but it was close. Reminded me of a Winston Churchill quote: "There is nothing more exhilarating than to be shot at without result."

I don't know enough about brakes to say if your master cylinder could be the problem. Maybe?
 

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Brake Booster?
 

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Shot gun it!

What's it cost for a Master Cylinder & Brake Booster?

The one thing to consider is you didn't have any brake issues until your ABS "Upgrade" and now it has classic symptoms of Air in the system. Either there's air trapped in the ABS module or you have a weak brake component that showed after the "Upgrade".
 

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All my LH cars with ABS have what I consider "Normal" pedal travel and firmness. I can think of only one time that ABS actually engaged on one car and the pulsating pedal and noise makes it obvious that ABS engaged.

I'll have to see if the Vident Scan tool I have will read/test/exercise the ABS module. I just checked it on my 2004 CAN Bus Durango and it worked. Don't know if it'll work with 2nd gen LH cars. I'll check it in the next few days once the rain stops.
 

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Discussion Starter #14
Thank you all for the feedback. I was planning on shot gunning it (replace the master and booster) but hoped I could be more “precise” with this forums expertise.:) Parts are ordered. Thanks all for confirming that ABS does cause a soft brake pedal.
 

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My bet, after replacing more parts you will find out that there is air in the system. Never assume the "pro" brake man is in fact a pro. He was working the tire department last month...
 

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Or even last week! LOL!
 
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I'll try my Vident scanner tomorrow to see if it will read/test/run the ABS module in my 2002 Special. Might not go back as far as PCI Bus vehicles as far as running the ABS pump to bleed brakes. It works as far back as 2004 on my Durango SLT CAN Bus SUV. I'll let you know. The Vident tool is around $156 on Ebay.
 

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But if air is trapped in the ABS system between the ABS valves, it will give a spongy pedal - at least on 2nd gen - I assume the same in 1st gen. The ABS valves have to be operated during a bleed cycle to get the air out.
Yes, this is true---if you dont have a scan tool----There is a shade tree trick around this----a gravity bleed---meaning no pressure applied during bleeding. One valve open at a time; for about 10 minutes. Valve closed, next one open. Starting with the closest valve to the ABS module (backwards from standard)....---that being said, a standard bleed has to be done first to get the majority of the air out of you'll be there all day.

I've done it many times, works great, just takes a while, but if you dont have a scanner to activate the ABS module;
 

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Yes, this is true---if you dont have a scan tool----There is a shade tree trick around this----a gravity bleed---meaning no pressure applied during bleeding. One valve open at a time; for about 10 minutes. Valve closed, next one open. Starting with the closest valve to the ABS module (backwards from standard)....---that being said, a standard bleed has to be done first to get the majority of the air out of you'll be there all day.

I've done it many times, works great, just takes a while, but if you dont have a scanner to activate the ABS module;
Good info., Dan.

How do you open the individual ABS valves? Are they electrically operated? I'm not seeing wires for the valves in the FSM.
 

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Good info., Dan.

How do you open the individual ABS valves? Are they electrically operated? I'm not seeing wires for the valves in the FSM.
No need; enough gravity bleed will pull the air out of the module. It will either travel back up the lines to the master, and up, out of the reservoir; or down thru the caliper bleeder---and out---depending on the brake fluid flow rate. You'd want your master cylinder absolutely full to the brim the whole time to help with pressure.

They are electrically operated; the module on top of the unit contains solenoids that operate the valves; and the pump motor. Its all one unit; with the control module attached. Sensor information and several PCM signals are fed into it--so there are no single wires to each solenoid---its a PCB.

Like the master cylinder the valves are in a "released" position when the ABS is not active--example---its the same concept if the master cylinder is in "released, or neutral" position, whichever you want to call it, fluid will pass thru from the reservoir to the brake lines if a bleeder is open. Air can remain in there during a normal pressurized brake bleed, but it is not totally trapped...hence the gravity bleed working.
 
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