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Sounds like it has RWALIs it the dash brake indicator light, which comes on when the park brake is applied, that is blinking?RWAL stands for REAR WHEEL ANTILOCK. RWAL was standard equipment starting in 1988 on full size trucks.The RWAL system can store trouble codes.The RWAL system is only capable of storing one code at a time.You can retrieve RWAL codes without a scan tool.To retrieve RWAL codes connect a jumper wire between terminal H and terminal A of the ALDL connector with the key on (engine not running). Watch the dash brake lamp and count the blinks. Sometimes RWAL system send out a phantom blink before the code blinks start. It can take up to 20 seconds for the code to start coming out.Checking the code with this method can set a false code 9.You can clear the code by removing the fuse for 10 seconds then reinstalling it. The fuse should be labeled STOP/HAZARD or BRAKE. Removing the RWAL fuse will not clear the code.If you get one long flash and 5 shorter flashes that is a code 6.If the light is blinking the manual states you should still check the codes by turning the key on (engine not running) and put a jumper wire between terminal A and H of the ALDL. Count the brake light flashes.On trucks built after Aug 1994 a scanner is required to retrieve codes 6,9,10This site tells how to read your codes.http://autorepair.about.com/library/faqs/bl929g.htm <<<<<<<<<<<This site has general information about RWAL.http://www.babcox.com/editorial/tr/tr89850.htmOn this system it is usually best to: XXXXX XXXXX code, clear the code, and drive the truck and see if the code returns.
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