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Author Topic: Antilock light  (Read 1956 times)

jmoore1540

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Antilock light
« on: January 18, 2008, 02:53:23 PM »
My anti-lock is now staying on all the time. I have good brakes, the pump runs, my brake light is on only during auto test at start, my traction assist is off. Is my problem an accumulator, control relay, or wheel sensors. I don't have a OBD II code reader and the Auto Zone near me will only read check engine lights. Some advice please. Seems thats all I've been doing since I joined. You guys seem to have more information than most clubs. As most of you know, I have a 1994 SC. Therefore, I must say again, Thank You.

rjstat

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Re: Antilock light
« Reply #1 on: January 18, 2008, 03:14:23 PM »
Here some info.
Antilock Brake System

DESCRIPTION
The ABS (ABS) is a four-wheel system which prevents wheel lock-up by automatically modulating the brake pressure during an emergency stop. By preventing the wheels from locking, it enables the driver to maintain steering control and to stop in the shortest possible distance under most conditions. The brake pedal force required to engage the ABS function may vary with the road surface conditions. A dry surface requires a higher force, while a slippery surface requires much less force.

OPERATION - OVERVIEW
During normal braking, the ABS and non-ABS brake pedal feel will be the same. During ABS operation, a pulsation can be felt in the brake pedal, accompanied by a fall and then rise in brake pedal height and a clicking sound.

OPERATION - ABS CYCLE
ABS operates as follows:


When the brake pedal is applied, fluid is forced from the brake master cylinder outlet ports to the Hydraulic Control Unit inlet ports.
This pressure is transmitted through four normally open solenoid valves contained inside the brake pressure control valve block, then through the outlet ports of the brake pressure control valve block to each wheel.
If the ABS control module senses that a wheel is about to lock, based on sensor data, it closes the normally open solenoid valve for that circuit. This prevents any more fluid from entering that circuit.
The ABS control module then looks at the sensor signal from the affected wheel again.
If that wheel is still decelerating, it opens the normally closed solenoid valve for that circuit. This dumps any pressure that is trapped between the normally open valve and the brake back to the accumulator.
Once the affected wheel comes back up to speed, the ABS control module returns the valves to their normal condition allowing fluid flow to the affected brake.
The primary (rear) circuit of the brake master cylinder feeds the right front and left rear brakes. The secondary (front) circuit of the brake master cylinder feeds the left front and right rear brakes.
OPERATION - ABS CONTROL UNIT


The ABS control module monitors the electro-mechanical components of the system.
Malfunction of the ABS will cause the ABS control module to shut off or inhibit the system. However, normal power-assisted braking remains.
The 4-wheel ABS is self-monitoring. When the ignition switch is turned to "RUN", the ABS control module will perform a preliminary self-check on the ABS electrical system indicated by a one-to-two second illumination of the amber ABS indicator.
During vehicle operation, including normal and ABS braking, the ABS control module monitors all electrical ABS functions and some hydraulic operations.
Each time the vehicle is driven, as soon as vehicle speed reaches approximately 20 km/h (13 mph), the ABS control module turns on the pump motor for approximately one-half second. At this time a mechanical noise may be heard. This is a normal function of the self-check by the ABS control module.
In most malfunctions of the ABS/traction control system, the amber ABS will be illuminated.
Most malfunctions are recorded as a diagnostic trouble code (DTC) in the ABS control module memory and assist in pinpointing the component needing service.
COMPONENTS


power brake booster.
brake master cylinder.
necessary brake tubes and hoses.
ABS hydraulic control unit (HCU).
brake pressure control valve block.
pump motor.
ABS control module.
front and rear brake ABS sensors.
-ABS pedal sensor switch
OUTPUTS
The ABS control module controls the operation of the following:


ABS power relay.
ABS motor relay.
ABS indicator.
ABS valve assembly.
BRAKE FLUID LEVEL SWITCH
There are two brake fluid level switches in use. One in in the master cylinder reservoir the other is in the hydraulic control unit reservoir. The switch on the master cylinder does not affect ABS operation. The Brake fluid level switch on the hydraulic control unit reservoir does control ABS operation.


Service and Repair

NOTE:
Tools:
The brake master cylinder and ABS hydraulic control unit must be bled using an ABS adapter.

Purpose:
If this procedure is not followed, air will be trapped in the ABS hydraulic control unit, which will eventually lead to a spongy brake pedal.

Bleed Sequence:
(1st) RH rear, (2nd) LH front, (3rd) LH rear, (4th) RH front.

THREE STEP PROCEDURE
The ABS must be bled in three steps.

Step 1
Bleed the master cylinder, if it was serviced or run dry, and perform Manual or Pressure Bleeding procedure. See: Hydraulic System\Service and Repair

Step 2
Perform ABS Bleeding procedure (below).

Step 3
Perform Manual or Pressure Bleeding procedure again. See: Hydraulic System\Service and Repair

ABS BLEED PROCEDURE


Disconnect the ABS wiring from the ABS control module and install the ABS adapter to the wire harness ABS wiring.
Place bleed/harness switch in bleed position.
Turn ignition to "ON" position. At this point, the red "OFF" indicator should turn on.
Push motor button on adapter down. NOTE: This starts the pump motor. The red "OFF" indicator will turn "OFF" and the green "ON" indicator will turn "ON". The pump motor will run for 60 seconds once the motor button is pushed. If the pump motor is to be turned "OFF" for any reason before this 60 seconds have elapsed, push the abort button and the pump motor will turn "OFF".
After 20 seconds of pump motor operation, push and hold the valve button down. Hold valve button for 20 seconds, then release. NOTE: The pump motor will continue to run for an additional 20 seconds.
Bleed the brake lines in the conventional manner.

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J dot Miller

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Re: Antilock light
« Reply #2 on: January 19, 2008, 02:48:19 PM »
I would first check the wheel sensors.  Take off the wheels and clean off the metal shavings and dirt from the wheel sensors.  Inspect them and see if they are damaged or bent.  If they are bent we will need to look at what to do further.

We collect the information from all the sites and combine it with our experience.  Please tell your friends.   :astronomer:
The 5.4 swap has been called a bad idea, and considered an underpowered considerable waste of time, since 2007.

Nice to see that most donít think that anymore.
Bondfreak13 07/28/09 09:05 PM

jmoore1540

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Re: Antilock light
« Reply #3 on: January 19, 2008, 05:05:21 PM »
THANK YOU VERY MUCH FOR THE INFO!!

jmoore1540

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Re: Antilock light
« Reply #4 on: March 16, 2008, 07:41:14 AM »
I blew a antilock fuse in the fuse block under the hood (ABS motor) Replaced it, not blown again, but now the red brake light stays on. I have repositioned the emergency brake handle to no avail. Still looking for a used pump and relay, so far without success for my '94 SC.

Any info/help? :(

J dot Miller

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Re: Antilock light
« Reply #5 on: March 16, 2008, 09:46:44 AM »
Is the pump running when you turn the key on?

As per Duffy if you place your ignition switch to the run position without starting the car you can watch this test being run. This self test will check electrical continuity of the system as well as the Electronic Controller for proper operation. The Amber Anti-Lock light will illuminate for approximately 4 seconds and then extinguish if all is well with your system.

If you then place the switch to the start position and start your car you should see the following cycling of lights. The Amber Anti-Lock and Red Brake Light should illuminate. The Hydraulic Pump Motor most likely will run since the pressure sensed by the Pressure Switch in the system is probably low (below 2030 PSI)if the car has been sitting a while. The Pressure Switch will allow power from the ANTI LOCK 10A Fuse to cause the Hydraulic Pump Motor Relay to close itís contacts allowing  power to flow to the pump motor from the ABS MTR 40 A fuse. It will also cause the Anti-Lock Warning Light to  be illuminated. The pump running will pressurize the hydraulic accumulator to around 2650 PSI at which point  the pressure switch contacts will open, the Hydraulic Pump Motor Relay will drop out and the pump will stop as  well as the red and amber lights will extinguish. For all applicable model years the Anti-Lock Power Relay and the Hydraulic Pump Motor Relay are located on the passenger side firewall area. When facing the engine bay these relays are located as follows:

89 Model Year (Left to Right) WOT AC Cutout Relay, Hydraulic Pump Motor Relay, Anti-Lock Power Relay
90 Model Year (Left to Right) WOT AC Cutout Relay, Hydraulic Pump Motor Relay, Anti-Lock Power Relay
91 Model Year (Left to Right) Hydraulic Pump Motor Relay, Anti-Lock Power Relay, WOT AC Cutout Relay
92 Model Year (Left to Right) Hydraulic Pump Motor Relay, Anti-Lock Power Relay, WOT AC Cutout Relay
The 5.4 swap has been called a bad idea, and considered an underpowered considerable waste of time, since 2007.

Nice to see that most donít think that anymore.
Bondfreak13 07/28/09 09:05 PM

KevSha

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Re: Antilock light
« Reply #6 on: March 17, 2008, 04:56:57 PM »
did you check the brake fluid...its good right... thats about the only thing that i can think that will throw the red light and not the abs light.....

maybe the level sensor is bad...hopefully not the pressure switch. i had that problem...

if you are still having problems still and you want to convert, there is a write up on it on SCCOA. this is what i WAS going to do, i removed my teves unit and found the pressure switch leaking.... thankfully i knew someone with a spare switch, because i could not find it new....

http://www.sccoa.com/forums/showthread.php?t=59901&highlight=vacuum+booster&page=15   its a huge post, but its allot of trial and error that people went through to figure out what works... the only problem is your pedal will never be as firm as it is with teves....but then again what's better a soft pedal or a REALLY hard pedal in rush our traffic....i had that scare....i thought i was going to die...thankfully it was just low on fluid because of that leak....
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jmoore1540

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Re: Antilock light
« Reply #7 on: March 25, 2008, 02:43:52 PM »
My pump isn't running and has blown a fuse. I will be replacing the HCM in its entirety. Hopeflly that will solve my problem with the ABS. :)

J dot Miller

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Re: Antilock light
« Reply #8 on: March 30, 2008, 11:43:40 AM »
Please keep us updated.   :surr:
The 5.4 swap has been called a bad idea, and considered an underpowered considerable waste of time, since 2007.

Nice to see that most donít think that anymore.
Bondfreak13 07/28/09 09:05 PM

jmoore1540

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Re: Antilock light
« Reply #9 on: April 06, 2008, 02:17:01 PM »
Will do.

J dot Miller

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Re: Antilock light
« Reply #10 on: April 08, 2008, 03:07:39 PM »
Any news?
The 5.4 swap has been called a bad idea, and considered an underpowered considerable waste of time, since 2007.

Nice to see that most donít think that anymore.
Bondfreak13 07/28/09 09:05 PM

jmoore1540

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Re: Antilock light
« Reply #11 on: May 05, 2008, 02:31:48 AM »
Finally got the part but haven't put it on yet. According to the Ford shop manual the brakes must be bled using an electronic tool which I don't have, so I'm waiting until I have the cash to have a shop put the part on and bleed the brakes as I don't have the tool. >:(

J dot Miller

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Re: Antilock light
« Reply #12 on: May 05, 2008, 09:28:39 PM »
You only need the tool if your abs accumulator is not charged.  A new accumulator comes charged.   I hear you can work around it...   Here is some info I foud on doing it wothout a tool:

Quote from: Joisey Jim
I'm sure it's a wonderfull tool, but I've had 3 SC's & still own 2 ('93 & '94). I've changed brakes about 7 or 8 times and replaced the whole fluid about 4 times, without any problems or special tools. You employ the ABS method by having the ignition on and applying the brake pedal once - which allows a 10  second automatic bleed each time for the rears & then the traditional method for the fronts. I never back-pressure the system and make sure I release the bleed nipple whenever the caliper pistons need pushing back. That usually requires a modest amount of top-up of the master cylinder reservoir. I've only fully bled the system when replacing the whole fluid ,about every 5 years or so. For me that has equaled a full pad change on the 5 speed (front & rears have usually lasted 50-60k) and every other pad change on the auto (fronts only last about 25-30k). So is the '95 different than the '94?


Quote from: BobGPz
Someone gave me a tip when I had problems getting air out of my Master Cylinder (M/C). Crack the three lines coming from the M/C and have a couple rags STUFFED under to catch the fluid. Have someone press/pump on the brake pedal (Not sure if the key has to be on) and hold pedal down while you loosen the 3 lines, one at a time, until looks like just fluid comes out. Tighten them up. Then you will need to turn the key/ignition to the ON posisition, and make sure you hear the ABS Pump start to fill accumulator. I got confused with the fuel pressure pumping up noise and the ABS Pump, so make sure the ABS Pump is working or you will get no fluid to the back calipers. Pump brakes and hold while you crack bleeders on calipers with a clear tube hose end completely submerged in to a jar or cup (Old brake fluid canister with a hole in cap for the hose works great too) with some fluid in it. Dont let the hose end come out of the fluid or you may suck air and have to start over. Also check and make sure the reservoir doen't get low, OR too full. The order to bleed that I did was:
1 passenger rear, 2 drivers rear, 3 passenger front, 4 drivers front. Heard the key can be turned off when doing the front calipers. Listen for the ABS Pump to turn on occasionaly when bleeding the rears. Also auto parts stores have a one man bleeder kit that I found works good, as my lazy @$$ exwife wouldn't pump me.

edit....my brake pedal that is...  :o


The 5.4 swap has been called a bad idea, and considered an underpowered considerable waste of time, since 2007.

Nice to see that most donít think that anymore.
Bondfreak13 07/28/09 09:05 PM