Compression Ignition Addict
Join Date: Oct 2011
Location: Tehachapi, CA
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From the factory service manual:
System Pre-Check Test C, Yellow REAR ABS Light Self-Check OK, but Light Automatically Begins Flashing
The RABS II warning light will automatically begin a flash-out sequence if the diagnostic line Circuit 571 or 483 is shorted to ground. This will result in a blown fuse for the Keep Alive Memory Power for the RABS II Module. 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
Intermittent RABS II module power circuit
Intermittent RABS II module ground circuit
Intermittent RABS II light circuit
Blown Keep Alive Memory fuse
C1 - Observe REAR ABS Light for Flash Sequence
Observe REAR ABS light and determine if the flashing is a diagnostic trouble code (one or more short pulses followed by one long pulse). Is the flash sequence a diagnostic trouble code?
Yes: Inspect Circuit 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.
No: Go to C2.
This sounds like your problem. The 15 short flashes an the one long flash is a code of 16. Here's the pinpoint test for Code 16:
Code 16 is always present, unless a system concern has been detected and a diagnostic trouble code has been stored. This code should be used by the technician to verify the RABS II system is OK.
Code 16 will be output by the anti-lock electronic control unit when one of two conditions exist:
1. The technician ground Circuit 571 (BK/O).
2. The RABS II Keep Alive Memory (KAM) fuse has blown.
If the KAM fuse has blown, the REAR ABS warning light will begin flashing Code 16 (or a diagnostic trouble code if a concern has been detected) if the stoplight switch is depressed (F-Series), or the running lamps are turned on (Econoline).
Therefore, check the KAM fuse when diagnosing complaints of RAER ABS light flashing.
There is also drive test for code 16 (I can post if needed, but it would take me a bit to copy out of the manual) that is done after system repair (usually done for other trouble codes). Hope this helps. Forgot to mention that Circuit 571 is the BK/O wire from the RABS II Module connector to the diagnostic connector. Circuit 483 is the R wire from the other side of the diagnostic connector to the KAM fuse. Cheers!
1997 F250 SC 4x4, E4OD, 4.10 LS, Basically Stock, Relocated Block Heater Plug, External Trans Filter, Tru-Cool Max, I/C Mounted but not Plumbed
SOLD - 1994 F350 CC DRW 2WD PSD, 5 Speed, 4.10 LS, SBC Con-O, Baldwin Filter, Tymar HPX Hose, DPPI DP, Bilsteins, $12 AIC, Coolant Filter, Explorer Overhead Console, A-Pillar w/ISSPRO Black Ice, EV Boost, and EV Pyro, Modified Pedestal, Gutted EBPV.
Last edited by Patrick Feeley; 05-06-2013 at 07:30 PM.
Reason: Added wiring description.