Brake problem question

T-bird Tim

Registered User
My buddy has an emaculate 90 SC auto. Just over 87k miles. The car is in awesome condition but started having a brake issue recently. The anti-lock light stays on but not the red brake light. The pedal is hard and it requires extra stopping distance but does eventually stop. Anyone think this could be just the accumulator or the whole master cylinder assembly? Any way to trouble shoot before he spends money unnecessarily? Thanks
 
Does the red brake light come on when starting the car? Unusual but not unheard of to have hard brake pedal and no red brake light. I would suggest getting the codes read before going off on a wild goose chase.
 
When the key is first turned both lights come on. Very shortly after the red one goes off and the yellow stays on. Is finding the codes easy? as in something auto zone could scan?
 
Could be a weak pump motor, or a worn accumulator, or faulty pressure switch. The lack of power assist usually points to the motor relay, accumulator, or pressure switch. However, if the relay, pressure switch, or motor were 100% bad, the lights would never go out. I'll bet the pump motor runs continuously, doesn't it?
 
Yellow ABS light simply means that the ABS computer has sensed a fault, and ABS functionality is not available.

The hard pedal tells you that it isn't a problem with a wheel sensor.. at least not yet.

This leaves quite a few possible components.
This page has some steps you can use to diagnose things. But if you can get codes pulled, it would help. Any shop that has an older code reader that can pull Ford DLC and ABS codes should work.
http://www.35thatr.org/Tips/ABS.htm
 
brake problem

Having just dealt with what sounds like a similar problem. Have the codes read as Duffy suggested. Thsi is the quickest and cheapest way to a solution.
Gerry
 
Could be a weak pump motor, or a worn accumulator, or faulty pressure switch. The lack of power assist usually points to the motor relay, accumulator, or pressure switch. However, if the relay, pressure switch, or motor were 100% bad, the lights would never go out. I'll bet the pump motor runs continuously, doesn't it?


Reason I asked about the Red Brake Light....he did not report it being on and I asked to verify it works. None of the above listed by you will give an Amber Anti-Lock Warning Light.

Get the codes read and go from there.
 
The car had a battery that wouldnt hold a charge so I put a good one in. I thought that this may have something to do with the brakes not operating properly. I drove it about three miles. The yellow light was still on but I had a good pedal for about two miles. The last mile or so it went back to having a hard pedal, so it seems that the problem is intermittent even though the light stays on.
 
Called my brother in Alabama who is a mechanic and owns two SCs. He told me to change the ABS relay module on the firewall. Just so happens that I had an extra one in my parts box. Switched it out and the yellow light has gone out. I drove it up the street and it didnt come back on and the pedal felt good. Sometimes the fix is so simple.
 
Hope it stays good. My 90 had the pressure switch fail and the pump wouldn't run. My 92 got the hard pedal, I changed the relay first since it's cheap, and it's been fine since. I guess sometimes you get lucky.
 
Reason I asked about the Red Brake Light....he did not report it being on and I asked to verify it works. None of the above listed by you will give an Amber Anti-Lock Warning Light.

Get the codes read and go from there.
A faulty pressure switch could. Its 2 stage. Nominal pressure (brake assist) and full pressure (ABS reserve). This is why I asked about the motor running all the time. The other thing it could be doing is overheating and shutting itself off.
Also, recall the ABS is completely separate from the power assist. If there is ever a loss of power assist, the problem cannot be the ABS. :D
 
Yes the Anti-Lock Pressure Switch has two contacts but neither contact positon gives you an Amber Anti-Lock Warning Light. Even if the Brake Fluid Level Switch actuates it does not give you the Amber Anti-Lock Warning Light even though it will shutdown the ABS Pump Motor.

"Also, recall the ABS is completely separate from the power assist. If there is ever a loss of power assist, the problem cannot be the ABS."

Mot sure what you mean by this statement. The Teves Mark II system is an integrated ABS System and the problem of hard brakes can certainly be caused by a problem in the Hydraulic Actuator Assembly.
 
Yes the Anti-Lock Pressure Switch has two contacts but neither contact positon gives you an Amber Anti-Lock Warning Light. Even if the Brake Fluid Level Switch actuates it does not give you the Amber Anti-Lock Warning Light even though it will shutdown the ABS Pump Motor.

"Also, recall the ABS is completely separate from the power assist. If there is ever a loss of power assist, the problem cannot be the ABS."

Mot sure what you mean by this statement. The Teves Mark II system is an integrated ABS System and the problem of hard brakes can certainly be caused by a problem in the Hydraulic Actuator Assembly.

I think what he means is that if the ABS module in the trunk fails, or one of the wheel sensors is bad, you still have brakes, just that the ABS will not function if you put them to the floor. Witout any pressure in the system, then you are looking at a problem with the pump motor itself, or the wiring and switches related to getting it to run.
 
I had a small fender bender, and when driving away I had no power brakes and a red light on.

After checking the area of the damage, behind the left headlight, I noticed a 5-6 prong connector that several wires came into and connected to ground through this male silver connector bolted to the body.
I plugged it back up and all is well, but it did have a TON of corrosion so I'm going to clean it all up this weekend, in case it causes a future problem.
 
"Also, recall the ABS is completely separate from the power assist. If there is ever a loss of power assist, the problem cannot be the ABS."

Mot sure what you mean by this statement. The Teves Mark II system is an integrated ABS System and the problem of hard brakes can certainly be caused by a problem in the Hydraulic Actuator Assembly.

Let me clarify as that read like a description of the later model ABS. The teves II ABS operates independently from the teves II power assist. You could unplug the ABS computer and your brakes would work fine just no antilock. For all its pros/cons, Ford got that right IMO.

Oh, and yes the antilock light is controlled by the ABS computer. The pressure switch sends 12V to the computer when the ABS pressure is available. If all other conditions are OK, the light is turned off. This is why you'll see the brake light go out first, followed by the anti-lock light upon startup.
 
Even after I changed the module I could hear the front brakes grinding when driving. I bought a new set of pads and put those on. I noticed the front ABS sensor was coated with metalic shavings. I cleaned that off. Also the front left brake pad was down to the rivets. I think this also could have triggered the light. Everything replaced now and no issues.
 
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