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.
Powertrain Control Module & Vehicle Control Module: Memories
2004 Oldsmobile Bravada AWDSECTION Memories
WARNING: This page does not describe the selected car, but rather 33 other vehicles, including the 2002 Saturn Vue, 2002 Pontiac Montana, 2002 Pontiac Aztek, 2002 Oldsmobile Silhouette, and 2002 Oldsmobile Bravada. However, it is still accessible from the selected car via links, so may be relevant.
PCM may use one or more of 6 types of memory:
- Calibration Package (CALPAC)
Some models use a Programmable Read Only Memory (PROM) and a CALPAC. CALPAC provides fuel delivery back-up so engine runs in case of PROM or PCM failure. Anytime PCM is replaced, PROM and CALPAC must both be installed into replacement unit. If battery voltage is removed, CALPAC information is retained. - Electronically Erasable Programmable Read Only Memory (EEPROM)
Some models may use an EEPROM. This is the same as a PROM except it can be electronically reprogrammed by the manufacturer using special equipment. - Memory Calibration (MEM-CAL)
Some vehicles may use a PCM containing a MEM-CAL unit. This assembly contains functions of PROM and CALPAC. If power to PCM is removed, MEM-CAL information is retained. MEM-CAL also contains an internal Knock Sensor (KS) module on models equipped with a KS system. - Programmable Read Only Memory -
PROM is factory programmed engine calibration data which "tailors" PCM for specific transmission, engine, emission, vehicle weight and rear axle ratio application. The PROM can be removed from PCM. If battery voltage is removed, PROM information is retained. - Random Access Memory (RAM)
RAM is the scratch pad for the CPU. Data input, diagnostic codes and results of calculations are constantly updated and temporarily stored in RAM. If battery voltage is removed, all information stored in RAM is lost. - Read Only Memory (ROM)
ROM is programmed information which only PCM can read. The ROM program cannot be changed. If battery voltage is removed, ROM information is retained.
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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.