Trouble Code 13 (1992-1994 Vehicles)

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During normal driving modes the PCM/TC adapts line pressure to prevent clutch slip and harsh shifts. This is accomplished by modulating the line pressure actuator ground (1530) to noise or lower pressure. Open circuit = high pressure, grounded circuit = low pressure. If the time required to make all shifts is too short and line pressure has been commanded low, it is determined that the actual line pressure is too high.

Code Parameters

DTC/information flag 13 is set when the PCM has detected the following conditions for more than 5 shifts:

  • Upshift pressure adaptive error is less than 112 which indicates over pressure. This condition must still exist after the up shift pressure adapters have reached the lower limit (Low Limit = 288 kPa).
  • Low load, low commanded pressure.
  • Transaxle oil temperature above 40°C (104°F).

Test Description

Numbered steps below refer to numbered steps on chart.

 1. Check for information flags 68, 69, or 95. They must be eliminated first as a possible cause of a DTC/information flag 13.
 2. Check actuator operation. Use actuator quick check. The actuator quick test will PWM the actuators at a set rate. 
   Listen and compare noise of the line pressure actuator to that of other actuators. The noise of all should be similar.
 3. Check pressure regulator valve operation. Make sure pressure increases in correct increments during pressure test. 
   If pressure changes erratically or moves in large increments, the pressure regulator valve is probably sticking.
 4. If little or no pressure change, the regulator valve is stuck. To verify, test for minimum and maximum oil pressure per oil pressure specification.

Diagnostic Aids

  • When the PCM detects a fault in the circuit (open, ground, short) the PCM will open the circuit internally to protect the circuit.
  • Could be a hot or cold only condition. If condition is Intermittent, try to reproduce DTC by checking malfunction (MALF) history table with Scan tool to see at what temperature the DTC will set and reproduce conditions.
  • This DTC may set or intermittent harsh upshifts may be caused by a poor electrical connection at either the PCM, actuator connector plate, or UHJB terminals. Wiggling connectors while performing an actuator quick test may isolate the problem area.