Body Control Module

1999 GMC Forward Control 5.7 R, AutomaticSECTION Body Control Module
WARNING: This page is about a different car, the 2003 Chevrolet Corvette. However, it is still accessible from the selected car via links, so may be relevant.

The Body Control Module (BCM) contains the theft deterrent system logic. The BCM reads the key code from the ignition cylinder when the ignition is turned to the START position. If the code is correct, the BCM will enable the theft deterrent relay and will send a fuel enable signal to the PCM via the class 2 serial data circuit.

If the BCM receives the wrong code, the BCM will immediately go into tamper mode. The tamper mode will lock-out the vehicle starter and fuel injectors for 3 minutes. The SECURITY indicator will flash while the BCM is in tamper mode.

RENDER: 1.0x

NO RELATED

Recommended Tools & Savings

Use the Manual With the Right Hardware

Pair factory procedures with proven DIY tools so the instructions are easier to execute.

Affiliate disclosure: We may earn a commission at no extra cost to you.

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • β€’ You smell fuel, burning insulation, or see smoke.
  • β€’ Brakes feel soft, pull hard to one side, or make grinding noises.
  • β€’ The engine overheats, stalls repeatedly, or misfires under load.
  • β€’ You are missing required tools, torque specs, or safe lifting equipment.
  • β€’ You are not confident in the next step or safety outcome.