ECM - Inter. No Cooling Fan/High Coolant Temp/Idle High

NO.:
92-T-48

DATE:
October, 1992

GROUP:
Engine

CORP. NO.:
286001



SUBJECT:
Intermittent No Cooling Fan or High Coolant Temperature, A/C Does Not Get Cold or Engine Idle May Be Increased (Cycle Ignition On/Off)

MODELS
AFFECTED:
All 1991 and 1992 Saturns

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.

NOTE:
If engine coolant temperature is 42~C (106~F) or above, it may take up to five minutes of ignition off time to reset the PCM.

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.