Powertrain Controls - ECM/PCM

Diagnostic Trouble Code (DTC) 73:

Pressure Control Solenoid Circuit.:

CIRCUIT DESCRIPTION
The pressure control solenoid is a Powertrain Control Module (PCM) controlled device used to regulate transmission line pressure. The PCM compares Throttle Position (TP) voltage, engine RPM and other inputs to determine the appropriate line pressure for a given load. The PCM will regulate the pressure by applying a varying amperage to the pressure control solenoid. The applied amperage can vary from 0.1 to 1.1 amp. The PCM then monitors the amperage at the return line.

DIAGNOSTIC TROUBLE CODE (DTC) 73 WILL SET WHEN
The return amperage varies greater than 0.16 amp from the commanded amperage for at least one second, and no DTC 75 stored.

ACTION TAKEN (PCM DEFAULT)
Full line pressure will be applied causing harsh shifts. DTC 73 will be stored in the PCM memory but will not turn "ON" the Malfunction Indicator Lamp (MIL).

DTC 73 WILL CLEAR WHEN
The fault condition(s) no longer exist, and the ignition switch is cycled "OFF" then "ON."

DTC CHART TEST DESCRIPTION
Numbers below refer to circled numbers on the diagnostic chart.

1. This test checks the ability of the PCM to command the pressure control solenoid.
2. This test checks for voltage at PCM.

DIAGNOSTIC AIDS
Check for poor connections at PCM and at transmission connector.

If pressure reading differ greatly form the line pressure chart below, refer to Transmissions and Drivetrain. Transmission Control Systems

Pressure Control Solenoid Line Pressure
Current (Amps) (PSI)

0.02 170 - 190
0.10 165 - 185
0.20 160 - 180
0.30 155 - 175
0.40 148 - 168
0.50 140 - 160
0.60 130 - 145
0.70 110 - 130
0.80 90 - 115
0.90 65 - 90
0.98 55 - 65