My brake light is flASHING 9 TIMES - 1989 GMC Sierra

have some one put a obd code reader on that i cant think of what would cause it to flash 9times and dont start

you yanked or damaged the VSS at that wheel ..a wire near your brake assembly that reads wheel speed for ABS cruise and data for OD systems

a flashing check light usually means a problem needs to be attended to right away most auto store such as advanced auto/auto zone etc offer free scanning to trouble code will give u a start location so u can make repairs if necessary

it means that your air-bag light flashes 1 time then stops then flashes 9 times. you probably have a lose connection somewhere

There a speed sensor problem. There are 2 fuses , make sure they are good, STOP?HAZ fuse and SPEED/RWAL fuse. A shop will neeed to check deeper if these are good.

Check the brake fluid, if not low it might be in need for service.

This truck probably has Rear Wheel Anti-Lock (RWAL) brakes. There is a small black module near master cylinder that is the brain for this system. There are ways to check for diagnostic trouble codes in this system. Once you have any codes set, diagnosis can be fairly simple. PROCEDURE:
Diagnostic Trouble Codes (DTC) 's can be displayed by jumping terminals "A" and "H" of the Data Link Connector and observing the flashing of the "BRAKE" warning light. This should only be done when the brake lamp is "ON".
The terminals must be jumped for about 20 seconds before the code will begin to flash. Count the number of short flashes starting from the long flash. Include the long flash as a count. Sometimes the first count sequence will be short. However, subsequent flashes will be accurate. If there is more than one failure, only the first recognized code will be retained and flashed.

NOTES:
DTC's 6, 9 and 10 will only turn the "BRAKE" lamp on while the fault exists. These are soft codes faults and can only be read with the Tech 1 scan tool.
Do not jump terminals "A" to "H" if the "BRAKE" lamp is not on. Jumping the terminals with the "BRAKE" lamp off will set a false DTC 9. This will turn the "BRAKE" lamp on and disable the antilock system.

1, 11, & 12 ECU Malfunction

2 Open Isolation Valve or Malfunctioning ECU

3 Open Dump Valve or ECU Malfunction

4 Grounded Antilock Valve Reset Switch

5 Eccessive Actuations of the Dump Valve

6 Erratic Speed Signal

7 Shorted Isolation Valve or Faulty ECU

8 Shorted Dump Valve or Faulty ECU

9 Open Circuit to Speed Signal

10 Brake Lamp Switch Circuit

13, 14 and 15 ECU Malfunction

9 times out of 10 its the brake switch located under the drivers side dash behind the brake peddle arm. However check the brake light fuses first.

could be lighting control module $$$$$$$ @400
it's above brake pedal area under dash. 6 x 4" approx.
Do high beams work? Flash to pass work?

if it's the lighting control module, it will provide a fault code when dealer tests it with NGS testor.


#9 is LCM, bottom left of pic.

One of your other indicator bulbs are gone- it cuold be one of the small ones in the front wings