EXPERTEC TSB (92-T-48-SATURN)

Publication date: 1992-10-01
Reference number: 92-T-48-SATURN

EXPERTEC TSB

TECHNICAL SERVICE BULLETIN

Reference Number(s): 92-T-48-SATURN, Date of Issue: 10/01/92

INTER. COOLING FAN OPERATION - - A/C DOES NOT GET COLD

Model(s): 1991-92 Saturn

Bulletin No.: 92-T-48

Date: 10/01/1992

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.