1, 2 and 3 Digit Codes: 74

CODE NUMBER
Scan tool: 74
General scan tool: P1799

CODE NAME
Calculated oil temperature in use

CODE DESCRIPTION
Technical Description
The TCM uses a thermistor to monitor the transmission's sump temperature. This temperature is used to determine which shift schedule the TCM is to use. If the thermistor circuit fails to operate properly the TCM will use the calculated oil temperature routine. If this occurs for three consecutive key starts, the code will be set. The TCM will then test the thermistor circuit after every 35 OBD II warm-up starts. If the thermistor circuit is OK, the thermistor data is used in place of the Calculated Oil Temperature Routine.

Check Area/Set Conditions
Whenever the engine is running. The code is set if any of the following conditions exist for three consecutive key starts:
- The thermistor voltage is out of range (below 0.07 volts or greater than 4.94 volts)
- If continuous erratic thermistor voltage is sensed.
- The thermistor temperature stays below 27°C (80°F) for an extended period of time.

Transmission Effects
If the thermistor indicates a temperature below O°F at start up, the TCM compares the calculated oil temperature to the indicated thermistor oil temperature. If the calculated oil temperature differs significantly from the thermistor value, the calculated oil temperature will be used for that key start.

PROBABLE CAUSE
- Malfunction of oil temperature sensor
- Harness or connector between transaxle range sensor and TCM open or short-circuited
- Malfunction of TCM





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