Rear antilock

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Pauliten02

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Has anyone disconnected rear abs in bronco? Pros and cons of doing so? My rear antilock warning light flashes once and stays on. Brakes seem to work fine. Not leaking any brake fluid.

Paul

 

miesk5

96 Bronco 5.0
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yo Paul,

The RABS system is found on all models except the F-Super Duty and 1993-96 Bronco models that have 4 Wheel ABS System (4WABS).

The RABS system constantly monitors rear wheel speed and, in the event of impending rear wheel lock-up in a sudden stop, regulates the brake fluid hydraulic pressure at the rear brakes to prevent total wheel lock-up, thus reducing the possibility of skidding.

RABS module won't ***** up the speedo or trans the way the 4WABS module can, and even if it goes bad, simply unplugging it removes it from the circuit

 VSS Wiring Diagram in an 89 5.0, 5.8 & 7.5  by Seabronc (Rosie, Fred W) at http://broncozone.com/topic/20547-fuel-pump-wont-shut-off/

I bypassed the 4WABS system (@ Module connector) in our 96 because Module blew out its microprocessors and affected PSOM & E4OD shifting; now I have old school braking.

 

miesk5

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yo,

I had to post quickly because Comcast was slowing down;

Here is the 89 5.0 RABS Wiring Diagram (pdf file)

http://www.revbase.com/BBBMotor/Wd/DownloadPdf?id=21134

Whenever the yellow REAR ABS light comes on during normal operation, a flashout code may be obtained to aid in problem diagnosis. If the vehicle is shut off before the code is read from a RABS-I module, the code will be lost. In some cases, the code may reappear when the vehicle is restarted. In other cases, the vehicle may have to be driven to reproduce the problem and, if the problem was associated with an intermittent condition, it may be difficult to reproduce. Therefore, whenever possible, it is recommended that the code be read before the vehicle is shut off. RABS II modules have been designed with Keep Alive Memory to preserve stored codes during key-off, and are to be used to service all prior year RABS I systems, except for 1987 and 1988 Bronco II vehicles.

WARNING: PLACE BLOCKS BEHIND THE REAR WHEELS AND IN FRONT OF THE FRONT WHEELS TO PREVENT THE VEHICLE FROM MOVING WHILE THE FLASHOUT CODE IS BEING TAKEN.

NOTE: If the red BRAKE light is also on, due to a grounding of the fluid level circuit (perhaps low brake fluid), no flashout code will be flashed and the REAR ABS light will remain on steadily. Top up the brake master cylinder reservoir before attempting to read codes.

NOTE: If there is more than one system fault, only the first recognized flashout code may be obtained.

Obtaining the Flashout Code
A flashout code may be obtained only when the yellow REAR ABS light is on. No code will be flashed if the system is OK. There are certain faults (those associated with the fluid level switch or loss of power to the module) that will cause the system to be deactivated and the REAR ABS light to be illuminated, but will not provide a diagnostic flashout code.

Before obtaining the flashout code, drive the vehicle to a level area, and place the shift lever in PARK for automatic transmissions and NEUTRAL for manual transmissions.

Notice whether the red BRAKE light is on or not (for future reference) and then apply the parking brake.

WARNING: PLACE BLOCKS BEHIND THE REAR WHEELS AND IN FRONT OF THE FRONT WHEELS TO PREVENT THE VEHICLE FROM MOVING WHILE THE FLASHOUT CODE IS BEING TAKEN.

To obtain the flashout code, locate the RABS diagnostic connector (with the Bk/Or wire); on '92-96, it's above the right end of the glove box bottom corner, inside the dash; on earlier trucks, it's between the brake & e-brake pedals near the firewall. Separate the R wire's connector half, turn the key to RUN, and attach a jumper wire to Bk/Or. Momentarily ground the Bk/OR jumper to the chassis (the lighter socket shell). When the ground is made and then broken, the REAR ABS light should begin to flash.

NOTE: If the red BRAKE light was on (as noticed before the parking brake was applied), the problem may be with the low fluid level circuit and, in this case, no flashout code will be flashed and the light will remain on steadily.

The code consists of a number of short flashes and ends with a long flash. Count the short flashes and include the following long flash in the count to obtain the code number. For example, three short flashes followed by one long flash indicates Flashout Code Four. The code will continue to repeat itself until the key is turned off. It is recommended that the code be verified by reading it several times. In addition, the first code flashed may be too short because it may have been started in the middle. It should be ignored.

After ALL codes have been read & repaired, clear the memory by turning the key off while the connector halves are separated, then reconnect the halves.

rabs-codes-92.jpg

RABS (& RABS-II) Flashout Codes Chart
 
OP
OP
P

Pauliten02

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So it should be unplugged and not connected to a female connector? What's the best way to bypass the abs system? Take out fuse?

 

miesk5

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yo Paul,
Every time I tried to reply  I got an error message.

I sent you a PM, but since we'll be away for a few days, I am copying the info  here so others can see where we're at on the issues:

RABS Code 9 Pin-Point Tests in a 91; part 1
Source: by Ford via Chilton
http://content.chilt...es/84929120.pdf

RABS Sensor ckt may have high resistance when it exceeds ~ 3K ohms

or failed internal module ckt
READ MORE

RABS Code 9 Pin-Point Tests in a 91; part 2
Source: by Ford via Chilton
http://content.chiltonsonline.com/content/images/8492/images/84929121.pdf

System will return to non-ABS operation

 
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miesk5

96 Bronco 5.0
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I have to validate all this later; I have to roll right now, but want to give you some EXCERPTS on possible casuses and checks;
Code: 9 — Speed Sensor Resistance or Open Speed Sensor Wiring
Affected Circuit(s)/Electrical Component(s)

Code 9 is generated by the module's detection of high speed sensor resistance. The module will consider the speed sensor circuit to have a high resistance when it exceeds approximately 3 K ohms. The code may also be generated by a failed internal module circuit. The module can only detect this condition when the vehicle is at rest.

Possible Contributing Base Brake Component/Vehicle Wiring Concerns
Terminal backout in the module harness connector at Pin 3 or Pin 10.
Terminal backout in the RABS speed sensor harness connector at Pins A or B.
Module or RABS speed sensor connectors not fully mated with component.
Open or intermittent open circuit in Circuits 519 (LG/BK) or 523 (R/PK).
VERIFY INTEGRITY OF SENSOR CONNECTION
Remove sensor connector.
Inspect sensor component connector for contamination or loose terminals.

Gently pull on Circuit 519 (LG/BK) behind Pin B of harness connector.
Gently pull on Circuit 523 (R/PK) behind Pin A of harness connector.
Terminals in component connector are clean and firmly in place. Terminal in harness connector is firmly engaged.
Leave sensor conector disconnected. GO to 9.3 .

Terminals in component connector are loose.
REPLACE RABS sensor. GO to 9.6 .

Terminal in harness connector moves back or comes free of connector.
SERVICE terminal or connector as needed

 

 

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