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Discussion Starter #1
Hey Guys,

A question about the ABS system on the 94 in my sig. Last night I had to jump on the brakes to stop quickly, when I did the brake pedal went halfway down. I kept pushing on the pedal as hard as I could and then the pedal dropped all the way to the floor.

At no time did the pedal pulsate as it does on the Jimmy, and when it went to the floor the truck was still stopping....it just did it very slowly.

What is the problem? Hydroboost bad? ABS module bad? Is this normal? Any insights?
 

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Commissioner Gordon
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It should act just like your Jimmy. Only thing I could think of is a weak master cylinder or air in the lines. The 1500 master cylinders (JB5) were some of the worst ones made back in the mid '90s.
 

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Discussion Starter #3
It should act just like your Jimmy. Only thing I could think of is a weak master cylinder or air in the lines. The 1500 master cylinders (JB5) were some of the worst ones made back in the mid '90s.
How does one check the master cylinder?
 

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does your truck have a hydroboost assist brake system..it should and this system will feel entirely different. Most hydroboost systems will allow the pedal to be pushed all the way to the floor with alot of effort
 

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Commissioner Gordon
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How does one check the master cylinder?
Easy diag. is to put the truck in drive and hold steady pressure on the brake pedal (like if your sitting at a stop light). If the pedal fades towards the floor (slow or fast) then the master cylinder is bad or there is a leak somewhere. The pedal should stay completely steady when you are stoped like that. Also check for a leak at the rear of the mastercylinder, that is a first sign of a failure.
Be sure to check for leaks in the brake system, most common are rear brake cylinders, front hoses or calipers and make sure your rear brakes are correctly adjusted (small amount of drag when hand spinning the drum).

I'm going to rule out the booster, (hydroboost right??) but starting simple is the best way to go.
 

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Discussion Starter #6
The truck does have hydroboost.

I will try your test and see what happens. I am assuming that if the truck passes there are no leaks and the problem must be elsewhere.
 

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Commissioner Gordon
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Sorry, my last sentence should have read; I'm Not going to rule out the hydrobooster, lets just start simple, first. Usually when a hydrobooster goes, it goes.
Have you tried to do an ABS stop in a controled area (backroad noone around)? Try and find a wet road (so you don't have to put to much stress on the brake system), and do a controled abs stop. This will be just to see if it does work and see how it feels. Maybe when you needed it last time 100million things were flowing through your head all at once and it felt wierd.

Something is just telling me that the master cylinder is getting weak or something else simple it causing the brake system to be weak. Do a look over and we'll go from there. Remember, brakes will work without abs, abs will NOT work without brakes.
 

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Discussion Starter #8
I tried the test and the truck failed miserably. The brake pedal held fine for a few seconds and then slowly dropped to the floor with me pushing on it quite hard.

After it failed the test I checked the brake fluid level and it is a little lower than it was last time I checked it (about a month ago).

I guess this means it is time for me to look for leaks. I won't be able to get it into my Dad's shop at the farm for a couple of weeks so I will keep my eye on the fluid level in the meantime.

Thanks for your help so far :)
I will let you know what I find.
 
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