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View Full Version : Hard/stiff brakes, but no brake or abs lights



three51stang
04-07-2011, 10:01 PM
I recently purchased a 91 SC with a 5sp and was coming down the exit ramp yesterday and the brakes became very hard. There is no power assist. I've been reading a lot of threads and have noticed everyone saying that their brake and abs indicators have come on. Mine have not and in fact they don't even come on when i first start the car or pull up the e-brake. I can hear the pump motor but it's not very loud (not sure if it should be) and it never shuts off. Any ideas or suggestions? Thanks so much for your help.

the-big-e
04-07-2011, 11:26 PM
The ABS and brake lights may be burnt out or not even in the cluster....

If your ABS motor is running all the time, it is either a bad relay that is stuck in the closed position or the pressure switch has failed.....

It sounds like the pump motor is wearing out.....

mmathews
04-08-2011, 02:49 AM
I never had an abs motor go nuts so i cant say your symptoms fit the bill. Would it pulsate constantly if it were? Really stiff brakes and no stopping power, for me, has been 90% of the time a vacuum leak. Or a clogged vacuum line. I bought a car where the previous owner duct taped a line to repair it. When the tape got hot it slid and the line sucked shut. I've also had a power brake booster fail and it was the same. The diaphrams in the canister can leak and viola, hard pedal and no brakes.

RalphP
04-08-2011, 07:48 AM
I never had an abs motor go nuts so i cant say your symptoms fit the bill. Would it pulsate constantly if it were? Really stiff brakes and no stopping power, for me, has been 90% of the time a vacuum leak. Or a clogged vacuum line. I bought a car where the previous owner duct taped a line to repair it. When the tape got hot it slid and the line sucked shut. I've also had a power brake booster fail and it was the same. The diaphrams in the canister can leak and viola, hard pedal and no brakes.

1991 ABS units ARE the power boost - no vacuum used.

It's a rather strange duck.

Google sometimes for "Teves Mk II Duffy" and read Duffy's tome on how it works, how it DOESN'T work, and how to fix it ...

RwP

three51stang
04-09-2011, 02:33 PM
The ABS and brake lights may be burnt out or not even in the cluster....

If your ABS motor is running all the time, it is either a bad relay that is stuck in the closed position or the pressure switch has failed.....

It sounds like the pump motor is wearing out.....

Okay well I did the test that Duffy suggested where you ground the #4 pin on the connector to the pressure switch and the motor did not turn on. So its sounds like the relay then, right? where is this thing located? Thanks

RalphP
04-09-2011, 03:22 PM
Okay well I did the test that Duffy suggested where you ground the #4 pin on the connector to the pressure switch and the motor did not turn on. So its sounds like the relay then, right? where is this thing located? Thanks

In Duffy's tome on the Teves Mk II brakes, he says where they are and which of the up to three is the ABS relay you're looking for (seems like Ford moved which one was which from one year to another ...)

BUT - passenger side, on the firewall, there's up to three relays. One is brown if it's still factory (and if you buy the replacement, Advance Auto has both a black one that's like $12 and the brown one that's like $23 or something - go ahead and get the brown one, so in 2025 when you do this again, it'll STILL be "the brown relay" :D

RwP

the-big-e
04-09-2011, 04:28 PM
go ahead and get the brown one, so in 2025 when you do this again, it'll STILL be "the brown relay" :D

RwP

LOL.....

Now that's funny.....:D

three51stang
04-09-2011, 05:23 PM
I just read the article and found where the relays are located and.... There's supposed to be 3 and there's only 2(neither are brown)!!! and according to Duffy on 91 T-birds the far left one is the Hydraulic Pump Motor Relay. And guess what? that's the one that's missing. I can see the mount where it's supposed to be and its no where to be seen. Any ideas?

RalphP
04-09-2011, 05:56 PM
I just read the article and found where the relays are located and.... There's supposed to be 3 and there's only 2(neither are brown)!!! and according to Duffy on 91 T-birds the far left one is the Hydraulic Pump Motor Relay. And guess what? that's the one that's missing. I can see the mount where it's supposed to be and its no where to be seen. Any ideas?

Advanced Auto lists a BWD replacement for about $12 ...

RwP

three51stang
04-09-2011, 06:53 PM
Okay so I replaced one of the two relays and nothing. Then I took the new relay back out and put it in the other spot. Still no good. I'm not sure if it was okay to do that.
The only other thing I could think of is that right after the brakes stopped working I added a bunch of brake fluid thinking it had just run low. It reads at the line now that says, "level with accumulator charged". This may be way to much considering the accumulator is probably not charged. I dunno... Just throwing out some ideas...

the-big-e
04-09-2011, 07:15 PM
You might have to dig down between the fender and the firewall....

Sometimes the brown relay will get lodged down there....

Have you checked for power at the pump motor connector located on the side of the master cylinder assembly....

three51stang
04-10-2011, 08:44 PM
You might have to dig down between the fender and the firewall....

Sometimes the brown relay will get lodged down there....

Have you checked for power at the pump motor connector located on the side of the master cylinder assembly....


Yeah I just looked again. Don't see it or feel it anywhere? Could it have came with only 2 relays?

I'll check for power next. Thanks

the-big-e
04-10-2011, 10:27 PM
There has to be a third relay somewhere in that area....

Or at least a connector where a relay would go....

The three relays are: WOT A.C. cutout relay, anti-lock power relay, and hydraulic pump motor relay.....

The first and second relays are grey and the third is the infamous brown relay....

There is a relay mounting tree attached to the firewall where all three relays are suppose to be secured....

All three relays will be within 3 - 5 inches of that mounting tree....

Use a flashlight, not a trouble light, to look down between the fender and fire wall....

three51stang
04-11-2011, 03:28 PM
There has to be a third relay somewhere in that area....

Or at least a connector where a relay would go....

The three relays are: WOT A.C. cutout relay, anti-lock power relay, and hydraulic pump motor relay.....

The first and second relays are grey and the third is the infamous brown relay....

There is a relay mounting tree attached to the firewall where all three relays are suppose to be secured....

All three relays will be within 3 - 5 inches of that mounting tree....

Use a flashlight, not a trouble light, to look down between the fender and fire wall....

Well I've looked a 3rd time and no luck. I've been very thorough. The mounting tree only had those two on it.

Also there's one grey relay and one black, not two grey. But I've noticed that the Black relay is plugged into a brown connector plug. Could someone have already replaced the brown relay with a black one?

Here's pics of the two relays.http://i41.photobucket.com/albums/e262/three51stang/IMG00365-20110411-1216.jpg
http://i41.photobucket.com/albums/e262/three51stang/IMG00366-20110411-1216.jpg
http://i41.photobucket.com/albums/e262/three51stang/IMG00364-20110411-1215.jpg
http://i41.photobucket.com/albums/e262/three51stang/IMG00363-20110411-1215.jpg

the-big-e
04-11-2011, 04:04 PM
So far, all of the SCs that I've checked have three relays.....

The first picture is the relay area for my 92 SC.....

All three relays are circled in red....

The second picture is an after market relay for the pump motor, it does have a brown retainer clip....

The last picture is the same relay that you have a picture of.....

I would think this is the anti-lock power relay....

You can check for proper relay operation.....

The relay will click when you add power to the two small terminals on the relay....

three51stang
04-11-2011, 08:35 PM
Well I unplugged the relay with the brown clip while the pump was running and it stopped so wouldn't this mean I have the correct relay?

Even if the relay were causing the pump to run all of the time wouldn't it still build up pressure in the accumulator and cause the brakes to work?

I'm thinking the accumulator is bad and never gets up to pressure, therefor causing the pump to run non-stop. What do you think?

the-big-e
04-11-2011, 11:33 PM
It is very possible that the accumulator is bad.....

When I had a pressure switch go bad, the pump motor ran all the time....

I had good brakes for about 18 months until the pump motor finally gave up....

After reading this entire post again (for the um-teenth time), I think your problem might be in the pump itself.....

There are a series of check valves in the pump and maybe one of them is bad.....

I say this because I've sold 3 pump units this year already compared to 0 units for the previous 7 years.....:confused:

Take the accumulator off and turn the ignition key on.....

A good pump / motor combo will shoot a good heavy stream of brake fluid about to 1 inch out of the top of the pump.....

Be careful as this will cause a mess.....:p

three51stang
04-12-2011, 03:25 PM
Okay, I'll try it. Thanks again for all your help. Greatly appreciated!

three51stang
04-12-2011, 05:25 PM
oh btw, do you put a wrench on the top of accumulator? Is there anything else involved?

the-big-e
04-12-2011, 05:29 PM
If it's an OEM accumulator, you can get a large allen wrench / socket on it....

If it is after market, then you will need a set of good strong hands, or a rubber strap wrench.....:p

Be careful as you unscrew the accumulator.....

Sometimes they will have quite a bit of brake fluid and pressure in them.....

Loosen it a few turns and let the pressure bleed off....

Again, this can get messy.....

three51stang
05-24-2011, 01:11 PM
If it's an OEM accumulator, you can get a large allen wrench / socket on it....

If it is after market, then you will need a set of good strong hands, or a rubber strap wrench.....:p

Be careful as you unscrew the accumulator.....

Sometimes they will have quite a bit of brake fluid and pressure in them.....

Loosen it a few turns and let the pressure bleed off....

Again, this can get messy.....


Ok got tied up with some other stuff but I finally got back to it. Took the accumulator off and turned the ignition on and nothing came out. Does this mean I have a bad pump?

the-big-e
05-24-2011, 03:41 PM
Does the motor run when you turn the ignition on.....

three51stang
05-26-2011, 02:24 AM
yeah it runs

the-big-e
05-26-2011, 09:27 AM
Take your accumulator off and run the pump motor....

A good pump will give you about a 1" geyser of brake fluid out of the accumulator fitting....

Micahdogg
05-26-2011, 11:13 AM
Pretty sure I only had two relays on my 1990 5 speed. And when the brakes went rock hard, replacing the relay fixed it (cant remember which one it was though).

three51stang
05-30-2011, 01:54 AM
Nevermind, I spun a bearing and I'm probably just going to sell it now.:(