Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
System Description: Notes
The Multiplex Control System has four internal functions:
- Multiplexing (send multiples signals over shared wires)
- Wake up/sleep (runs at full power only on demand to reduce battery draw)
- Fail-safe (fixes or ignores faulty signals)
- Self-diagnosis (Mode 1 for the system, Mode 2 for input lines)
The system controls the function of the following circuits
- Engine Oil Pressure Indicator
- Seat Belt Reminder
- Lights-on Reminder
- Key-in Reminder
- Key Light Timer
- Dash Lights Brightness Control
- Entry Light Control (ignition key light and ceiling light)
- Automatic Lights-off
- Power Door Locks
- Power Window (including key-off timer operation)
- Wiper/Washer (including speed sensitive intermittent wiper)
- Security Alarm
- Interlock system
- Memory Mirror Control
- Driving Position Memory System (DPMS)
- OnStar System
Use the Manual With the Right Hardware
Pair factory procedures with proven DIY tools so the instructions are easier to execute.
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.
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