Code 81 - Brake Switch Circuit: Notes

VCM monitors the brake switch circuit. If a brake signal does not occur within 10 seconds after vehicle speed is greater than 35 MPH, VCM sets Code 81. A faulty brake switch or related circuit problem can cause Code 81. If ANTI-LOCK light comes on at 15 MPH (speed increasing) and goes off at 15 MPH (speed decreasing), brake switch circuit is open.

Fig 1: Code 81 - Schematic (4.3L M/T - VIN Z)

Courtesy of GENERAL MOTORS CORP.

Fig 2: Code 81 - Schematic (Except 4.3L M/T - VIN Z)

Courtesy of GENERAL MOTORS CORP.

Fig 3: Code 81 - Brake Switch Circuit - Flow Chart

Courtesy of GENERAL MOTORS CORP.