ABS light flashing
ABS light flashing
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Joined: Apr 2005
Posts: 5,720
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From: Washington state
is the Dash Red Brake light on?
Description
The RABS II warning light will automatically begin a flash-out sequence if the diagnostic connector is shorted to ground. An open Keep Alive Memory (KAM) fuse is the most likely cause of a grounded diagnostic connector.
Possible Contributing Base Brake Component/Vehicle Wiring Concerns
l Intermittent RABS II module power circuit.
l Intermittent RABS II module ground circuit.
l Intermittent RABS II light circuit.
l Blown fuse.
² C1: OBSERVE REAR ABS LIGHT FOR FLASH SEQUENCE
² C2: INTERMITTENT POWER TO MODULE
² C3: DAMAGED MODULE GROUND
Yellow RABS light flashing indicates RABS computer may have stored error failure code or there is intermittent power to RABS module.
C1 OBSERVE REAR ABS LIGHT FOR FLASH SEQUENCE
l Observe REAR ABS light and determine if the flashing is a diagnostic trouble code (one or more short pulses followed by one long pulse).
Flash sequence is a diagnostic trouble code
INSPECT Circuits 571 (BK/O) and 483 (R) for short to ground. REPAIR circuit and REPLACE RABS KAM fuse. (See owner's manual.) Repeat «System Pre-Check» .
Flashing sequence is not a diagnostic trouble code
GO to «C2».
C2 INTERMITTENT POWER TO MODULE
l Remove the module harness connector from the module.
l Set voltmeter to 20VDC scale.
l Turn the ignition to the ON position.
l Shake the instrument panel harness while measuring battery voltage between Pin 1, Pin 9 and chassis ground.
Voltage is steady and greater than 9 volts
GO to «C3».
Voltage is intermittent or less than 9 volts
REPAIR Circuit 601 (LB/PK). Repeat «System Pre-Check» .
System Pre-Check
The RABS II uses both the red BRAKE and yellow REAR ABS instrument panel warning lights to alert the driver to a system malfunction. Both lights must be working properly to assist in concern diagnosis. The steps listed below must be followed prior to beginning the RABS II diagnostic procedure.
NOTE:
This repair procedure is written for REAR ABSII (RABS II) systems (as opposed to REAR ABSI [RABS I] systems). RABS II systems are standard for 1992 and 1993 Aerostar, as well as 1993 Rangers. In the event that you are not sure if you have a RABS I or a RABS II system in your vehicle, check the module part number. RABS II module part numbers will begin with either: F29F-2C018- or F37F-2C018-. All other part numbers should be considered to be a RABS I. If you have a RABS I module, you must refer to the repair manual for that model year vehicle.
Vehicle Setup
For 4-Wheel Drive vehicles, shift into 2-Wheel Drive. Drive the vehicle to a level area, and place the shift lever in PARK for automatic transmissions and NEUTRAL for manual transmissions. Turn the ignition off, set the parking brake and turn on the running lamps. Place blocks behind the wheels.
WARNING:
PLACE BLOCKS BEHIND THE REAR WHEELS AND IN FRONT OF THE FRONT WHEELS TO PREVENT THE VEHICLE FROM MOVING WHILE THE SYSTEM PRE-CHECK IS BEING DONE.
Release the parking brake and continue to Brake Light Self-Check.
Brake Light Self-Check
The Red BRAKE warning light is used to indicate a low fluid level condition or parking brake applied condition. To check this light, insert the key in the ignition lock cylinder and turn it to the START position. The light should glow in this position. If it fails to glow, service the electrical system as required. Go to «System Pre-Check Test B, Red Brake Light OFF and Does Not Self-Check.»
Allow the key to spring back from the START position to the RUN position. At this time the red BRAKE light should turn off. If it does not turn off, recheck the parking brake switch to make sure that it is fully dis-engaged. If the red BRAKE light is still ON, service the Base Brake System. In the event that the red Brake light remains on, go to «System Pre-Check Test E» , Red Brake Light ON.
Rear Anti-lock Bulb Self-Check
The yellow REAR ABS warning light is used to indicate a malfunction and a deactivation of the RABS II. To check this light, first follow the procedure above for Brake Light Self-Check, and allow the key to spring back from START position to the RUN position. The REAR ABS light should perform a self-check by glowing for approximately two seconds and then turn off. If it fails to glow, service the RABS II lamp electrical system. Go to «System Pre-Check Test A» ,Yellow REAR ABS Light OFF and Does not Self-Check. If it turns back on and does not flash, then a system concern has been detected. Refer to procedures for obtaining diagnostic trouble code.
Rear Anti-lock Bulb Automatically Flashing After Bulb Self-Check
If the yellow REAR ABS warning light begins to flash, this indicates that the Keep Alive Memory (KAM) power to the RABS II module has been disrupted. If this condition occurs, service the RABS II KAM power system as required. Go to «System Pre-Check Test C,» Yellow REAR ABS Light Self-Check OK, but light Automatically Begins Flashing.
Obtaining the Diagnostic Trouble Code (DTC)
NOTE:
Verify the ignition switch is in the RUN position. (NOTE: engine does not need to be running). Next, locate the black RABS II diagnostic connector. The diagnostic connector has two mating halves (one of which has a black/orange wire connected to it). Disconnect the two halves.
NOTE:
Some Aerostar vehicles were built with locking terminals in the diagnostic connector, making it difficult to disconnect the two mating halves. Use the following procedure if servicing an Aerostar with locking terminals:
1. Lift the latch on the female housing to disengage the locking mechanism.
2. Attempt to separate the two connector halves until the terminals lock.
3. On the top portion of the connector housing, opposite the mounting tabs, there is a small hole. Insert a narrow blade screwdriver or scribe type tool into the hole until it stops.
4. Separate the two connector housing halves by pushing the tool handle towards the black/orange wire.
Attach one end of a jumper wire to the black with orange stripe wire side of the diagnostic connector. Momentarily ground the opposite end of the jumper wire by connecting it to a good chassis ground for 1-2 seconds. Grounding this wire should start the REAR ABS lamp flashing. If grounding this wire does not start the REAR ABS lamp flashing, go to «System Pre-Check Test D» , Yellow REAR ABS Light Self-Check OK, but no flashout code when diagnostics is started.
CAUTION:
Care must be taken to connect only the black/orange stripe wire to ground. Connecting the mating connector wire to ground will result in a blown fuse.
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 diagnostic trouble Code 4. 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. This code will be used later for system repair instructions, it should be written down for future use. A diagnostic trouble code of 16 will be obtained when the module detects normal system operation.
Clearing the Keep Alive Memory (KAM)
The last step of the System Pre-Check always includes clearing the Keep Alive Memory (KAM). To do this, simply turn off the ignition while the diagnostic connector halves are separated as described in the procedures for obtaining the diagnostic trouble code above, after which the diagnostic connector should be re-assembled to provide KAM power to the RABS II module. If at this time a valid code has been obtained, go to the appropriate pinpoint test for that code.
Description
The RABS II warning light will automatically begin a flash-out sequence if the diagnostic connector is shorted to ground. An open Keep Alive Memory (KAM) fuse is the most likely cause of a grounded diagnostic connector.
Possible Contributing Base Brake Component/Vehicle Wiring Concerns
l Intermittent RABS II module power circuit.
l Intermittent RABS II module ground circuit.
l Intermittent RABS II light circuit.
l Blown fuse.
² C1: OBSERVE REAR ABS LIGHT FOR FLASH SEQUENCE
² C2: INTERMITTENT POWER TO MODULE
² C3: DAMAGED MODULE GROUND
Yellow RABS light flashing indicates RABS computer may have stored error failure code or there is intermittent power to RABS module.
C1 OBSERVE REAR ABS LIGHT FOR FLASH SEQUENCE
l Observe REAR ABS light and determine if the flashing is a diagnostic trouble code (one or more short pulses followed by one long pulse).
Flash sequence is a diagnostic trouble code
INSPECT Circuits 571 (BK/O) and 483 (R) for short to ground. REPAIR circuit and REPLACE RABS KAM fuse. (See owner's manual.) Repeat «System Pre-Check» .
Flashing sequence is not a diagnostic trouble code
GO to «C2».
C2 INTERMITTENT POWER TO MODULE
l Remove the module harness connector from the module.
l Set voltmeter to 20VDC scale.
l Turn the ignition to the ON position.
l Shake the instrument panel harness while measuring battery voltage between Pin 1, Pin 9 and chassis ground.
Voltage is steady and greater than 9 volts
GO to «C3».
Voltage is intermittent or less than 9 volts
REPAIR Circuit 601 (LB/PK). Repeat «System Pre-Check» .
System Pre-Check
The RABS II uses both the red BRAKE and yellow REAR ABS instrument panel warning lights to alert the driver to a system malfunction. Both lights must be working properly to assist in concern diagnosis. The steps listed below must be followed prior to beginning the RABS II diagnostic procedure.
NOTE:
This repair procedure is written for REAR ABSII (RABS II) systems (as opposed to REAR ABSI [RABS I] systems). RABS II systems are standard for 1992 and 1993 Aerostar, as well as 1993 Rangers. In the event that you are not sure if you have a RABS I or a RABS II system in your vehicle, check the module part number. RABS II module part numbers will begin with either: F29F-2C018- or F37F-2C018-. All other part numbers should be considered to be a RABS I. If you have a RABS I module, you must refer to the repair manual for that model year vehicle.
Vehicle Setup
For 4-Wheel Drive vehicles, shift into 2-Wheel Drive. Drive the vehicle to a level area, and place the shift lever in PARK for automatic transmissions and NEUTRAL for manual transmissions. Turn the ignition off, set the parking brake and turn on the running lamps. Place blocks behind the wheels.
WARNING:
PLACE BLOCKS BEHIND THE REAR WHEELS AND IN FRONT OF THE FRONT WHEELS TO PREVENT THE VEHICLE FROM MOVING WHILE THE SYSTEM PRE-CHECK IS BEING DONE.
Release the parking brake and continue to Brake Light Self-Check.
Brake Light Self-Check
The Red BRAKE warning light is used to indicate a low fluid level condition or parking brake applied condition. To check this light, insert the key in the ignition lock cylinder and turn it to the START position. The light should glow in this position. If it fails to glow, service the electrical system as required. Go to «System Pre-Check Test B, Red Brake Light OFF and Does Not Self-Check.»
Allow the key to spring back from the START position to the RUN position. At this time the red BRAKE light should turn off. If it does not turn off, recheck the parking brake switch to make sure that it is fully dis-engaged. If the red BRAKE light is still ON, service the Base Brake System. In the event that the red Brake light remains on, go to «System Pre-Check Test E» , Red Brake Light ON.
Rear Anti-lock Bulb Self-Check
The yellow REAR ABS warning light is used to indicate a malfunction and a deactivation of the RABS II. To check this light, first follow the procedure above for Brake Light Self-Check, and allow the key to spring back from START position to the RUN position. The REAR ABS light should perform a self-check by glowing for approximately two seconds and then turn off. If it fails to glow, service the RABS II lamp electrical system. Go to «System Pre-Check Test A» ,Yellow REAR ABS Light OFF and Does not Self-Check. If it turns back on and does not flash, then a system concern has been detected. Refer to procedures for obtaining diagnostic trouble code.
Rear Anti-lock Bulb Automatically Flashing After Bulb Self-Check
If the yellow REAR ABS warning light begins to flash, this indicates that the Keep Alive Memory (KAM) power to the RABS II module has been disrupted. If this condition occurs, service the RABS II KAM power system as required. Go to «System Pre-Check Test C,» Yellow REAR ABS Light Self-Check OK, but light Automatically Begins Flashing.
Obtaining the Diagnostic Trouble Code (DTC)
NOTE:
Verify the ignition switch is in the RUN position. (NOTE: engine does not need to be running). Next, locate the black RABS II diagnostic connector. The diagnostic connector has two mating halves (one of which has a black/orange wire connected to it). Disconnect the two halves.
NOTE:
Some Aerostar vehicles were built with locking terminals in the diagnostic connector, making it difficult to disconnect the two mating halves. Use the following procedure if servicing an Aerostar with locking terminals:
1. Lift the latch on the female housing to disengage the locking mechanism.
2. Attempt to separate the two connector halves until the terminals lock.
3. On the top portion of the connector housing, opposite the mounting tabs, there is a small hole. Insert a narrow blade screwdriver or scribe type tool into the hole until it stops.
4. Separate the two connector housing halves by pushing the tool handle towards the black/orange wire.
Attach one end of a jumper wire to the black with orange stripe wire side of the diagnostic connector. Momentarily ground the opposite end of the jumper wire by connecting it to a good chassis ground for 1-2 seconds. Grounding this wire should start the REAR ABS lamp flashing. If grounding this wire does not start the REAR ABS lamp flashing, go to «System Pre-Check Test D» , Yellow REAR ABS Light Self-Check OK, but no flashout code when diagnostics is started.
CAUTION:
Care must be taken to connect only the black/orange stripe wire to ground. Connecting the mating connector wire to ground will result in a blown fuse.
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 diagnostic trouble Code 4. 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. This code will be used later for system repair instructions, it should be written down for future use. A diagnostic trouble code of 16 will be obtained when the module detects normal system operation.
Clearing the Keep Alive Memory (KAM)
The last step of the System Pre-Check always includes clearing the Keep Alive Memory (KAM). To do this, simply turn off the ignition while the diagnostic connector halves are separated as described in the procedures for obtaining the diagnostic trouble code above, after which the diagnostic connector should be re-assembled to provide KAM power to the RABS II module. If at this time a valid code has been obtained, go to the appropriate pinpoint test for that code.
Thread Starter
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Senior User
Joined: Jan 2008
Posts: 140
Likes: 0
Thank you.
1 blown fuse.
Knocked out my DR lights, park lights, and made the ABS light flash.
I may have to bump that fuse up to a 20 amp as I think my trailer lights blew it.
Sniff, sniff......is that burning wiring I smell?? Gotta chance it.
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stevieray
1987 - 1996 F150 & Larger F-Series Trucks
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Sep 18, 2001 05:36 AM
