Transmission Controls With PCM

Diagnostic Chart:

Circuit Schematic:

LINE PRESSURE LOW
During normal driving modes the PCM adapts line pressure to prevent clutch slip and harsh shifts. This is accomplished by modulating the line pressure actuator ground (1530) to raise or lower pressure. Open circuit = high pressure, grounded circuit = low pressure. If there is too much slip in all gears and line pressure has been commanded high, it is determined that actual line pressure is too tow.

DTC PARAMETERS
DTC 14 is set when the PCM has detected the following conditions within the same ignition cycle:
- Transaxle diagnostic trouble codes 16, 22, 23, and 24 are detected.
- Since these diagnostic trouble codes are set, no forward gears are available.

TEST DESCRIPTION
Numbered steps below refer to numbered steps on chart.
1. Check for information flag 68. It must be eliminated first as a possible cause of a DTC 14.
2. Check actuator operation. 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.

NOTE: Prior to performing actuator quick check, the fuel pump probe hole must be connected to 12 volts. See "Actuator Quick Check". Component Tests and General Diagnostics

- If noise is faint or not present, replace the line pressure actuator. Be sure to check all connections at the actuator and connector plate before replacing the actuator.
- If noise is audible, same as other actuators, the pressure regulator valve may be binding in the bore or there is pump damage.

3. Check pressure regulat9r valve operation. Make sure pressure increases in correct increments during pressure test.
4. If no gears are available, a DTC 18 will probably be set. Make sure pressure increases in correct increments during pressure test. If pressure changes erratically and moves in large increments, the pressure regulator valve is probably sticking in the bore.
5. Check for the following conditions:
- Pressure regulator valve stuck.
- Sump suction filter restricted.
- Internal leak, casting or pump to case seal leak.
- Pump problem

DIAGNOSTIC AIDS
- Could be a hot or cold only condition. If condition is intermittent, try to reproduce conditions in malfunction (MALF) table to reset the code.
- When the PCM detects a fault in the circuit (open, ground, short) the PCM will open the circuit internally to protect the circuit.