Hello Everyone,

I have a ' 93 Aerostar 3.0, I recently got new front brake discs installed because of warping. After that the Brake and Rear ABS lights came on. The mechanic bled the brakes and checked the sensors, he cannot find out the problem.
I took the van to the ford dealership they put it on the computer and concluded the master cylinder and all the sensors (brake & abs)needed to be changed.
Then I took the van to another mechanic, he said that all the sensors needed to be changed.

At this point since the brake are mechanically fine, I would like to check the sensors.

Can anyone please help me to locate the brake and rear abs sensors?

Any advise will be appreciated.

93Aerostar

 

Welcome to FTE! You just did yourself a big, big favor by dropping in here for advice. Everyone you have spoken with so far has been less than truthful about your problem.

Rear anti-lock problems are probably the biggest source of complaints on this forum and they usually occur like yours, just after minor brake work. Without opening any of the posts, scroll down to the bottom of this forum to the search box and type in RABS or antilock and see all the various posts.

As to specifics for your problem, often just bleeding the rear brakes will equalize the pressure in the RABS (rear antilock brake system) control unit. When you do the bleeding, do not push the brake pedal more than halfway down. It is generally a good idea to flush all the old brake fluid so buy two quarts and spend some time bleeding the entire system until the fluid runs clear. Another tip: During the bleeding process do not allow the master cylinder fluid level to drop low enough to introduce air into the system or you will generate other problems.

Likely as not, this will solve your problem. The dealerships know all this as well. For one to tell you the entire system needs replaced is reprehensible and certainly not deserving any future support from you as a customer.

Good luck and keep us posted!

 

After you bleed the brakes as recommended by aerocolorado, if the lights are still on you will have to begin troubleshooting the brake system to determine which sensor(s) are causing the lights to remain on. With my 92 3.0L 2wd I have the same problem after fixing a leaking rear cylinder and a broken front line.

On some systems the master cylinder includes both a low fluid level sensor and a proportioning valve/differential pressure sensor. The low fluid sensor is located on the resevoir and the proportioning valve sensor is located to the front of the master cylinder.

On my 92 the master cylinder and proportioning valves are separate. My proportioning valve is a combination valve sensing pressure differential to the front and rear systems and metering fluid between the front brakes and the ABS valve. Using the procedure below I have found the pressure differential sensor of my combination valve to be tripped. Next is to rebleed my system to try to force the piston back to its normal position or disassemble and clean the combination valve as I know I have no leaks.

If your MC has two electrical connectors, one directly below the resevoir and the other to the front of the MC, then you have the first type. Check the pressure differential sensor first by disconnecting the electrical connection at the front of the MC and shorting the connectors in the wiring harness together with a paper clip. If the lights go out then you have a problem with the pressure differential sensor itself, or you actually have a pressure difference between the front and rear systems. If the light does not go out, the reconnect the pressure differential sensor. Disconnect the fluid level sensor and using the paper clip again short the wiring harness connections. If the lights go out, you have a bad fluid level sensor.

If your system is like mine with a separate combination valve, follow the wiring from the other side of the fluid level sensor and it will lead you to the combination valve. Mine is located on a bracket directly below the MC. Again check the pressure differential switch first as indicated above, and then the fluid level switch.

I recommend checking the pressure differential sensor first because the pressure differential sensor is feed power through the fluid level sensor. If you just check the fluid level sensor and the lights go out, you may replace a MC that is good and still have a bad pressure differential switch. Of course, if the pressure differential switch is part of the MC you may end up replacing it anyway.


To locate the ABS valve, follow the brake lines from the MC. Mine is located below the proportioning valve in the engine compartment directly below the master cylinder. The ABS valve has two cylindrical towers on top and a large electrical connector on the side. Testing of the ABS valve requires specialized tools, but at least you will have eliminated the MC, fluid level sensor and pressure differential sensor as the problem.

LOL

Ron

 

Thanks for the advice guys. It's supposed to warm up here in New Jersey, so I'll try your suggestions this weekend.

I'll bleed the brakes and check out the MC and abs valve.

By the way, getting off the subject for a second, is there a way I can get some more power to the engine. I was thinking about a performance air intake or exhaust.

Thank you, this is my first time on a forum, I look forward the camaderie.

93aero

 

93aero,

On adding power you can search this forum and find lots of mods done from intakes to exhausts. They can give you great advice on just about everything you might want to try and many have probably already tried many of the aftermarket mods you might wish to consider.

Let us know what you find on your brakes. LOL and Happy Holidays to you and yours.

Ron