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Jaxer Smith
Jaxer Smith, Auto Mechanic
Category: Chevy
Satisfied Customers: 1272
Experience:  17 yrs Experience and Own and Operate My Own Service Center
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Why is my in dash brake warning light on my 89 gmc 1500

Resolved Question:

why is my in dash brake warning light on my 89 gmc 1500 flashing?
Submitted: 9 years ago.
Category: Chevy
Expert:  Jaxer Smith replied 9 years ago.

Hi, Welcome to Just Answer!

Sounds like it has RWAL

Is 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 6,9,10

This site tells how to read your codes. <<<<<<<<<<<

This site has general information about RWAL.

On this system it is usually best to: ***** ***** code, clear the code, and drive the truck and see if the code returns.

Let me know if you need further assistance.

Jaxer Smith and other Chevy Specialists are ready to help you
Customer: replied 9 years ago.
Mr Smith. Thank you for your timely reply. I was unaware of any rear wheel antilock. the truck was a base model 2wd work truck.   could tthis explain the soft brakes? also when i bled the lines some air was in the lines? and my rear brakes still make a clunking noise when comming to a stop. any thoughts?   well thank you again and ill see what i can figure out.