DESCRIPTION & OPERATION
Input signals from sensors are sent to the Powertrain Control Module (PCM). The PCM controls shift or converter clutch application. The PCM can also determine line pressure needed to optimize shift feel.
Five electronic solenoids accomplish these functions as follows
- 2 On/Off solenoids for shifting.
- One Pulse-Width Modulator (PWM) solenoid for Torque Converter Clutch (TCC) control.
- One Electronic Pressure Control (EPC) solenoid for line pressure control.
- One 3-2 timing/coast clutch solenoid to control release of coast clutch, coordinated release of the direct clutch, and apply of the low and intermediate band.
PCM has built-in self-diagnosis, fail-safe code and warning code display for the main input sensors and solenoid valves.
Hardware Limited Operational Strategy (HLOS)
If a number of system or sensor failures are present and PCM is not receiving enough information to operate, PCM will switch to HLOS mode. PCM will output fixed values to allow operation of vehicle. Driveability concerns will be present. PCM will not output service codes in this mode.
Description
Following procedures are functional tests of EEC-IV system. These 4 basic test steps must be followed in sequence to avoid misdiagnosis
- VISUAL CHECK and EQUIPMENT HOOKUP
- KOEO (Key On Engine Off) SELF-TEST
- KOER (Key On Engine Running) SELF-TEST
- CONTINUOUS MONITOR MODE (WIGGLE TEST)