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Cadillac Repair/1990 Cadillac Fleetwood

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Expert: - 11/27/2011


Question
Hi it is me again regarding the 1990 Cadillac Fleetwood. You said not to touch the round container next to the master cylinder that it was for the abs system(i think). We need to find information on how to change the hydro boost and master cylinder because everything is connected together with the black round container. I bought a book but it sucks. Is there any place on line that can help us. Thanks again for all your help.

We believe it is the hydro boost because half way down the line we get fluid to the rear breaks but then it stops and we can't get it out of the rear breaks. Plus when the car is turned on the book says you should hear the hydro boost kick on for about 2 minutes but there is no noise from the boost.

Answer
Hello,

Hydraulics for the braking system and hydraulics for the hydro boost are 2 separate issues. The booster is only for brake assist and not for fluid to get to the rear. The metering valve controls fluid to front and rear brakes.

From what I remember, you had at one time had the master cylinder empty. This could have uncentered the metering valve which controls fluid to front and rear. You also had to fill the power steering fluid for the hydro boost which one has to ask where did it go? In the unit causing it to fail. 2 different issues and you need the service manual to sort it all out.

Did you try the old fashioned way of bleeding the rear brakes instead of gravity? Did you open the bleeder have someone step on the brakes to see if fluid would come out, tighten and repeat?
The brake assist has to be fixed first so you can tell if the pedal will go down properly in the first place without effort.

If you fix the brake assist (hydro boost)that only controls the amount of pedal pressure for stopping and has nothing to do with brake fluid pressure. You have a 21 year old car which makes it difficult (not impossible) to obtain decent repair information. If this was a 2005, you could go to http://www.alldata.com and download a service manual for $30.
Because of its age you are left with only one other option. Try Ebay or Craigs list to see if you can obtain a factory service manual for the car.

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Rob Painter

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Alarm system questions cannot be answered on this forum. These systems are not what I can answer. Without being physically at the vehicle and not knowing what kind of electrical service has been done on the vehicle, there is no possible way to give an accurate answer over the internet. My expertise is in Ignition/key based anti-theft systems. These issues include GM VATS (resistor chip in key blade) PASSLOCK (MRD)-ignition lock rotation based, no special ignition key and the PKIII Transponder (computer chip in key) systems. These systems are not alarm based and are integral with the starting of the engine. This is why I cannot diagnose alarm problems without physically looking at the vehicle: Alarm systems are a completely different annimal than ignition key/lock based anti-theft system. Many alarm questions come from vehicles 10 years old, and since older, many hands that had been involved over the years.I am an expert in all GM factory (ignition/key based)systems. Alarm system questions pose to many situations beyond my knowledge as to what has been done to the vehicle over the years. Some guy may have actually wired the stereo into the alarm system. Who knows? Over my past 30 years in vehicle wiring repair, I have seen unbelievable wiring disaters done by guys that consider themselves "mechanics." I have seen stereos and alarms intalled using surgical tape. I have seen modules burn up, un-fused circuits, wiring jambed between the doors and even lamp cord used for a starter kill. To answer alarm questions over the internet without examining the vehicle is like asking; What does it take to remove a dent?

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Education/Credentials-ASE certified. 11 years with a GM dealer and 17 years with a repair facility dealing with only the repair of theft recovered vehicles.

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