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I have a 1991 ford Aerostar. The abs light and brake light come on while driving. The car surges while driving and off and on and the car shakes real hard at times while driving, like the abs system is coming on and thinks the brakes are locking up. We are out of town and want to make sure we make it 800 miles home safely. Just had master cylinders replaced in rear.
Submitted: 3 years ago.
Category: Ford
Expert:  Steve replied 3 years ago.

Steve :

Welcome and thanks for your question. My name isXXXXX will do whatever I can to answer your questions!

Steve :

If the brake light and the abs light are coming on at the same time then the master cylinder is low on brake fluid.

JACUSTOMER-z5krrxkd- : So what needs to be done to fix it? And why is the abs system trying to come on while driving/ causing a lot of shaking in car and slight surging while driving?
Steve :

Does it shake when coming to a stop?

JACUSTOMER-z5krrxkd- : No while accelerating and just coasting. It comes and goes. And smelling burning a burning fluid smell.
Steve :

That does not sound brake related, that sounds like you have a misfire in the engine. Possibly you have some bad spark plugs and spark plug wires.

JACUSTOMER-z5krrxkd- : Just had it in to Firestone this am, I don't think they know what they are talking about. It won't have problems after the car has been off and lights will be off for the first 5 minutes of driving, then it starts acting up. P
Steve :

I would first check the brakes master cylinder for being low on brake fluid to repair the light. If you engine is shaking on acceleration and coasting that is a engine misfire.

JACUSTOMER-z5krrxkd- : That would cause the rear end of the car to shake. Engine is running good. And smell burning fluids? And why brake lights on if its spark plugs?
Steve :

The shaking is coming from the rear of the van?

JACUSTOMER-z5krrxkd- : Yes, it is. Had drive shaft checked for looseness, and u bolts are ok.
JACUSTOMER-z5krrxkd- : Firestone suggested that abs pump is going out but before I spend that kinda money I want to make sure. I read something about a seal in the abs pump? Or can the fuse be pulled for the abs system to see if it fixes the problem?
Steve :

You have two separate concerns. One is the light. The light is coming on because the master cylinder is low on fluid. The second concern is the vibration from the rear. This is usually caused by a drive shaft imbalance, bad u- joint. Could be a bad tire in the rear.

JACUSTOMER-z5krrxkd- : We drove 800 miles with no problems with the shaking. Shaking did not occur until I had master cylinders replaced and new shoes.
Steve :

If it started right after they put the shoes on then they probably messed something up replacing the shoes and the wheel cylinders.

Steve :

I would have there work double checked by someone.

JACUSTOMER-z5krrxkd- : How do we check the brake fluid in the master cylinder?
Steve :

You open the hood of the van and on the drivers side in the back corner is a master cylinder. It is a clear bottle with marks on it for full and low see if it is full.

JACUSTOMER-z5krrxkd- : The brake fluid container? Ok going to check now. Should car be running or not?
Steve :

Does not matter, Ill send you a pics so you know what to look for.

JACUSTOMER-z5krrxkd- : Brake fluid full to top. It seems as if the antilock brake system is coming on while driving.
Steve :

The antilock brakes do not activate unless you step on them. If it is activating or vibrating when you are stepping on the brakes and it only started acting up after the rear brakes were done, it is possible the rear brakes are the concern.

Steve :

Let me know i you have any other questions thanks.

Steve :

do you have any other questions on your concern?

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Category: Ford
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Experience:  30 years working for Ford dealer. Ford Master tech.
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