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Questions and Answers

Chevy C1500 Brake Light Is On

Q. Hello Vince. Hope this finds you doing well. I recently bought a 1991 Chevy C1500, automatic transmission and a 350 engine. The emergency park brake light stays on in dash. Brakes have been bled, electric tester thing has been put on all applicable places, (I am a female and just asked a couple of guys friends to look at it at different times).

Chevy C1500 Brake Light Is On

Ruled out switch immediately under park brake. Used to when you moved park brake back and forth light would go bright and then get dimmer, now it stays bright, can't remember the name of it but under the hood a guy was messing with something and the light would go out but would come back on few minutes later.

I have the manual on this truck and have tried reading through it, but would appreciate any advice you could give regarding this. My brakes work good and I am driving it. If you use exact names (unlike me) I will look in the manual to find out exactly what you are talking about. Hope you can help.

A. 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.

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.

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.

Chevy C1500 Brake Light Is On

  • 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

Additional Information provided courtesy of ALLDATA

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