New accumulator is in and.......HELP

MikeM

Registered User
I got my new accumulator in and the Antilock and Brake lights are still on. The pump seems to continuously run. Would a bad relay cause the lights to come on? Or, would the system still need to charge for a while to get up to pressure.

Any advice is appreciated and most definitely needed.
 
Do you have good brake pressure with the pump continuously running? If you do, then the new accumulator is probably fine, but that relay is most likely shot.

I still don't know a whole ton about my car yet, so perhaps someone else may know of something else that could be wrong. Just a thought though, if you replaced that accumulator, wouldn't you need to bleed the whole brake system again?
 
I have perfect brake pressure while pump is running. I also have brake pressure for several pumps after the car is off. I know the accumulator is good. And it also seems that, even though my ABS light is on, my ABS work. I went to a gravel parking lot and slammed the brakes and my ABS seemed to work. I may have just been feeling the rough ground, but it felt liek my pedal was pulsating. I'll have to get another body there to be sure.

Anyways....would my brake lights be on if the relay was pooched?
 
The antilock lite is tripped by low pressure which is determined by the pressure switch. Its actually a bi-level switch.. first level shuts off the brake lite, second level shuts off the pump. You didn't bend any wires or leave any disconnected or anything like that when you replaced the accumulator, did you?

I don't know where to get a pressure switch, you might have to call around places like prior remanufacturing or check out parts america or one the suppliers listed by SCCOA. Be sure to check the fluid level in the reservoir too, that can cause the brake light to come on.
 
Low fluid level will cause the lites to come on. Check the plug on the top of the resavour and over fill it a little. See if that helps.
 
Check the Fluid then the ABS Pump Relay

If the hydraulic pump is running continously, that is a bad situation. This will quickly cause the pump to fail from overheating. First, make sure you have enough brake fluid. When you removed the bad accumulator, it was probably full of fluid. As the new one is pressurized, it will take fluid from the reservoir. If there isn't enough available, the pump will try to compensate by continuing to run. If the pump runs after the key is off, then the relay is stuck. This will drain the battery and kill the pump. If the relay is bad, get a GP Sorensen #MR120 relay from your local parts house. BTW, the relay is located up next to the firewall on the passenger side. It is dark brown and should say ABS Pump Only on it. I don't think it is a problem with the pressure sensor/switch. When that fails, the pump generally stops cycling.
 
Exact same thing happened to me after I replaced my accumulator... changed the relays... same problem. Went to Ford... new pressure switch... all better now.
 
I'd suggest you check the pump relay first, but from what you've described, it doesn't sound like the problem. The way relays fail doesn't mesh with the problem you've described. If the relay didn't engage (failed open), you would have no power brakes.. its that simple.. If the relay stayed engaged (failed closed) you would have a pump running continuously even with the key off.

You stated that you have power assist and ABS. This means that: the pump runs, it charges the accumulator to its working pressure, the pump relay is engaged. The only way for the relay to close is from a signal from the pressure switch (from my memory, its a direct connect.. not through some other relay or circuit). Look at it this way: Start with the key off and pressure low, like would be if your car were parked. Now, when you switch on the key, the low pressure engages the relay which turns on the pump motor, as the pressure starts to rise, the ABS computer is signaled first (the light goes out) when the minimum pressure is reached. The pump continues to run until the 2nd pressure setting is reached and the pump shuts off.

If the ABS computer doesn't get the signal (maybe from a broken or shorted wire or faulty pressure switch) it would light the antilock light, but the brakes would function just fine and the pump would cycle as its supposed to.

So, to reaffirm, does the pump cycle on/off as its supposed to, and is the proper amount of fluid in the reservoir and which light(s) stay lit in which sequence from key on.
 
Check all the wires around the master cylinder. TbirdSCFan is probably on the right track that the high Pressure Sensor for the hydraulic pump has failed. This sensor tells the pump when to stop pumping because the set pressure is reached.

Could simply be some dirt got into the system when you installed the new acumulator and it's causing the pressure sensor issue.

I'd start there. Certainly don't run the car with that happening, as you will burn out that pump real fast. If you must, pull the relays so you get no assist.
 
The pump will shut off, but only because it has reached its protection limit, meaning it shuts off so it won't overheat and break. Fluid is perfect and no dirt would have goten in while the switch-over took place. I am leaning towards the pressure switch myself. Where is it located and how much does it generally cost?


Thanx

-Mike
 
Check the easy thing first. Fluid level! Low brake fluid will cause both lights to stay on. Add a bit more fluid and see what happens :)
 
I'm not sure where the pressure switch is located. I guess I would try prior-reman and see if they can give you the price for the switch as well as it's location. It'll be on the valve body somewhere... just not sure where.
 
The pressure switch is located on the vavle body, your right. Prior doesn't sell the switch though, only full units or accumulators. I have decided to go with a new unit. I am going to look in scrap yards first, and then I guess I will have to fork out the dough for a Prior unit.........
 
Isn't the pressure switch available from Ford? I know several others have had to replace the same switch so you must be able to get a new one somewhere.
 
$260 for that part? Yowch!

There is another supplier listed on SCCOA for rebuilt ABS units.. you might see if they can help you out. Also, see if the TBSCEC site can guide you. Oh.. and get a part# and contact Dan at Arizona Ford to see if he can do anything. http://www.fivestarford.com
 
Note that Prior may be saving us a bit by selling only a complete system. While electrical issues could fail a pressure switch early, typically if the switch fails, everything else is near failure already and should be replaced.
 
Excellent News

I found and picked up an ABS unit from a yard today. What a chore it was tracking one of these bastards down. I had to drive 1.5 hours out of town to pick it up. It's off a 92 SC........I have my fingers crossed that it still works.

Guess I'll be busy tomorrow doing the swap.......wish me luck!
 
The problem on these types of parts is twofold. One, this is a major safety device and you don't need to take the chance. Second, everyone you find in the junkyard is going to be over 10 years old so not much better shape than the one you already have. I would go for the Prior unit if it's not one of the firewall relays.


I made bad decisions like these when I was younger. When I was 18, I Drove 26 minutes on the highway with a cracked rubber caliber brake hose. Every pump caused the pedal to eventually go to the floor. I even new it was dumb, and I should just pull off the highway and take it to a garage. I didn't have the money to pay to have it fixed and just drove home.

At 32 that wont happen. I was lucky I didn't have to brake hard. If I would have tried there would have been no chance.

Jerry
 
Back
Top