CONDITION: An internal powertrain control module (PCM) serial peripheral interface (SPI) communication failure.
With an SPI communication failure, technicians and some customers may comment on intermittent:
- Cooling fan operation or high coolant temperature
- A/C does not get cold
- Increased engine idle speed in Park or Neutral
- No RPM signal or tachometer inoperative with vehicle running
An SPI failure causes all of the listed conditions to happen at the same time.
CAUSE: An SPI communication failure occurs during an incorrect PCM power down that can be caused by repeated cycling of the ignition, calibration download, battery connect or disconnect.
CORRECTIVE ACTION: Turn the ignition off, wait 10 seconds to reset the PCM and then start the vehicle.
If any of the vehicle symptoms of intermittent no fan operation or high coolant temperature, no A/C cool down, increased idle, or no RPM or tachometer inoperative still exist, refer to the appropriate Saturn Service Manual section.
General Motors bulletins are intended for use by professional technicians, not a "do-it-yourselfer". They are written to inform those technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions and know-how to do a job properly and safely. If a condition is described, do not assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See a General Motors dealer servicing your brand of General Motors vehicle for information on whether your vehicle may benefit from the information.