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; 2 On/Off solenoids for shifting, 1 Pulse-Width Modulate solenoid for torque converter clutch control, a Electronic Pressure Control solenoid for line pressure control, and a 3-2 timing/coast clutch solenoid to control the release of the coast clutch and the coordinated release of the direct clutch and apply of the low and intermediate band. The PCM has built-in self-diagnosis, fail-safe mode and fault 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 & Equipment Hookup
- KOEO (Key On Engine Off) SELF-TEST
- KOER (Key On Engine Running) SELF-TEST
- Continuous Monitor Mode (Wiggle Test)