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RABS (& RABS-II) Flashout Codes Chart
IF THE IMAGE IS TOO SMALL, click it.

Two warning lamps are located on the instrument panel to alert the driver to a system malfunction. The red brake warning lamp is used to indicate conventional brake system malfunctions such as low fluid level, parking brake applied and low vacuum conditions (diesel engines only). The yellow anti-lock system warning lamp is used to indicate proper warning lamp circuit operation (2 second illumination with ignition On or START). If the yellow lamp comes on while the vehicle is being driven, it is alerting the driver of an anti-lock system malfunction, and the yellow lamp can then be used to access flashout codes. This self-test feature contains codes to indicate area of system malfunction. When a malfunction is detected within the system, the computer module will shut down the anti-lock system and illuminate the yellow warning lamp on the instrument panel. This will permit normal braking and at the same time will store a code in the system memory which can be retrieved by grounding the diagnostic connector of the computer module and counting the number of flashes of the yellow light. If the ignition is turned off before diagnosis is performed (early RABS-1 modules only), the code stored will be lost. In this case, the vehicle must be started and driven to reproduce the condition. If more than one fault exists, only the first code recorded will be displayed. Additional codes will output only after the first fault has been corrected. The possible flashout codes are listed and explained in the Flash Codes Chart. Note that Codes 1 and 16 are not used.



Flashout Codes

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.

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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.

If a RABS(-1) module is installed, keep the ignition key in the ON position so that the code will not be lost. 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.

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.
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Brake System (Red) Warning Lamp
To check the brake system warning lamp, turn the ignition key to the Start position. The red warning lamp should glow momentarily. The warning lamp will also illuminate if the parking brake mechanism is not fully released. If the warning lamp fails to glow, service of the electrical system is indicated. If the warning lamp illuminates with the ignition key in the Run position, check and repair the conventional brake system as required. If the conventional brake system is found to be operating properly, check the anti-lock brake system for stored codes as outlined under ``Accessing Flashout Codes.'' In certain instances both the red and yellow warning lamps will glow simultaneously. If this occurs, check and repair the conventional brake system as required. If the red warning lamp continues to glow, refer to the ``Warning Lamp Condition Chart,'' Fig. 4, for proper diagnostic and testing procedures, then refer to Tests A through F, as required.

Anti-Lock Brake System (Yellow) Warning Lamp
To check the anti-lock brake system warning lamp, turn the ignition key to the On position. The yellow warning lamp should glow for approximately two seconds and should then shut off. If the warning lamp fails to glow, or glows continuously, refer to the ``Warning Lamp Condition Chart,'' Fig. 4, for proper diagnostic and testing procedures, then refer to Tests A through F, as required. In addition, if the warning lamp continues to glow during vehicle operation, check the anti-lock brake system for stored codes as outlined under ``Accessing Flashout Codes.''
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