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.
1999 Chevrolet Forward Control P12FACTORY OEM SERVICE PROCEDURE
Electronically Erasable Programmable Read Only Memory (EEPROM) Programming
WARNING: This page is about a different variant/trim than selected.
- The replacement Powertrain Control Module (PCM) comes with the EEPROM already programmed. However, the PCM must be programmed, with proper immobilizer signal for anti-theft system before the vehicle will start. See appropriate ANTI-THEFT SYSTEMS article in ACCESSORIES & EQUIPMENT for programming immobilizer signal.
- Once PCM is programmed, perform powertrain On-Board Diagnostic (OBD) system check. See POWERTRAIN ON-BOARD DIAGNOSTIC (OBD) SYSTEM CHECK in appropriate SELF-DIAGNOSTICS article in ENGINE PERFORMANCE.
Factory Service Tools
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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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